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postgres/src/backend/replication/logical/worker.c
Amit Kapila 7a85073290 Reconsider pg_stat_subscription_workers view. 
It was decided (refer to the Discussion link below) that the stats
collector is not an appropriate place to store the error information of
subscription workers.

This patch changes the pg_stat_subscription_workers view (introduced by
commit 8d74fc96db) so that it stores only statistics counters:
apply_error_count and sync_error_count, and has one entry for
each subscription. The removed error information such as error-XID and
the error message would be stored in another way in the future which is
more reliable and persistent.

After removing these error details, there is no longer any relation
information, so the subscription statistics are now a cluster-wide
statistics.

The patch also changes the view name to pg_stat_subscription_stats since
the word "worker" is an implementation detail that we use one worker for
one tablesync and one apply.

Author: Masahiko Sawada, based on suggestions by Andres Freund
Reviewed-by: Peter Smith, Haiying Tang, Takamichi Osumi, Amit Kapila
Discussion: https://postgr.es/m/20220125063131.4cmvsxbz2tdg6g65@alap3.anarazel.de
2022-03-01 06:17:52 +05:30

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/*-------------------------------------------------------------------------
* worker.c
* PostgreSQL logical replication worker (apply)
*
* Copyright (c) 2016-2022, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/backend/replication/logical/worker.c
*
* NOTES
* This file contains the worker which applies logical changes as they come
* from remote logical replication stream.
*
* The main worker (apply) is started by logical replication worker
* launcher for every enabled subscription in a database. It uses
* walsender protocol to communicate with publisher.
*
* This module includes server facing code and shares libpqwalreceiver
* module with walreceiver for providing the libpq specific functionality.
*
*
* STREAMED TRANSACTIONS
* ---------------------
* Streamed transactions (large transactions exceeding a memory limit on the
* upstream) are not applied immediately, but instead, the data is written
* to temporary files and then applied at once when the final commit arrives.
*
* Unlike the regular (non-streamed) case, handling streamed transactions has
* to handle aborts of both the toplevel transaction and subtransactions. This
* is achieved by tracking offsets for subtransactions, which is then used
* to truncate the file with serialized changes.
*
* The files are placed in tmp file directory by default, and the filenames
* include both the XID of the toplevel transaction and OID of the
* subscription. This is necessary so that different workers processing a
* remote transaction with the same XID doesn't interfere.
*
* We use BufFiles instead of using normal temporary files because (a) the
* BufFile infrastructure supports temporary files that exceed the OS file size
* limit, (b) provides a way for automatic clean up on the error and (c) provides
* a way to survive these files across local transactions and allow to open and
* close at stream start and close. We decided to use FileSet
* infrastructure as without that it deletes the files on the closure of the
* file and if we decide to keep stream files open across the start/stop stream
* then it will consume a lot of memory (more than 8K for each BufFile and
* there could be multiple such BufFiles as the subscriber could receive
* multiple start/stop streams for different transactions before getting the
* commit). Moreover, if we don't use FileSet then we also need to invent
* a new way to pass filenames to BufFile APIs so that we are allowed to open
* the file we desired across multiple stream-open calls for the same
* transaction.
*
* TWO_PHASE TRANSACTIONS
* ----------------------
* Two phase transactions are replayed at prepare and then committed or
* rolled back at commit prepared and rollback prepared respectively. It is
* possible to have a prepared transaction that arrives at the apply worker
* when the tablesync is busy doing the initial copy. In this case, the apply
* worker skips all the prepared operations [e.g. inserts] while the tablesync
* is still busy (see the condition of should_apply_changes_for_rel). The
* tablesync worker might not get such a prepared transaction because say it
* was prior to the initial consistent point but might have got some later
* commits. Now, the tablesync worker will exit without doing anything for the
* prepared transaction skipped by the apply worker as the sync location for it
* will be already ahead of the apply worker's current location. This would lead
* to an "empty prepare", because later when the apply worker does the commit
* prepare, there is nothing in it (the inserts were skipped earlier).
*
* To avoid this, and similar prepare confusions the subscription's two_phase
* commit is enabled only after the initial sync is over. The two_phase option
* has been implemented as a tri-state with values DISABLED, PENDING, and
* ENABLED.
*
* Even if the user specifies they want a subscription with two_phase = on,
* internally it will start with a tri-state of PENDING which only becomes
* ENABLED after all tablesync initializations are completed - i.e. when all
* tablesync workers have reached their READY state. In other words, the value
* PENDING is only a temporary state for subscription start-up.
*
* Until the two_phase is properly available (ENABLED) the subscription will
* behave as if two_phase = off. When the apply worker detects that all
* tablesyncs have become READY (while the tri-state was PENDING) it will
* restart the apply worker process. This happens in
* process_syncing_tables_for_apply.
*
* When the (re-started) apply worker finds that all tablesyncs are READY for a
* two_phase tri-state of PENDING it start streaming messages with the
* two_phase option which in turn enables the decoding of two-phase commits at
* the publisher. Then, it updates the tri-state value from PENDING to ENABLED.
* Now, it is possible that during the time we have not enabled two_phase, the
* publisher (replication server) would have skipped some prepares but we
* ensure that such prepares are sent along with commit prepare, see
* ReorderBufferFinishPrepared.
*
* If the subscription has no tables then a two_phase tri-state PENDING is
* left unchanged. This lets the user still do an ALTER TABLE REFRESH
* PUBLICATION which might otherwise be disallowed (see below).
*
* If ever a user needs to be aware of the tri-state value, they can fetch it
* from the pg_subscription catalog (see column subtwophasestate).
*
* We don't allow to toggle two_phase option of a subscription because it can
* lead to an inconsistent replica. Consider, initially, it was on and we have
* received some prepare then we turn it off, now at commit time the server
* will send the entire transaction data along with the commit. With some more
* analysis, we can allow changing this option from off to on but not sure if
* that alone would be useful.
*
* Finally, to avoid problems mentioned in previous paragraphs from any
* subsequent (not READY) tablesyncs (need to toggle two_phase option from 'on'
* to 'off' and then again back to 'on') there is a restriction for
* ALTER SUBSCRIPTION REFRESH PUBLICATION. This command is not permitted when
* the two_phase tri-state is ENABLED, except when copy_data = false.
*
* We can get prepare of the same GID more than once for the genuine cases
* where we have defined multiple subscriptions for publications on the same
* server and prepared transaction has operations on tables subscribed to those
* subscriptions. For such cases, if we use the GID sent by publisher one of
* the prepares will be successful and others will fail, in which case the
* server will send them again. Now, this can lead to a deadlock if user has
* set synchronous_standby_names for all the subscriptions on subscriber. To
* avoid such deadlocks, we generate a unique GID (consisting of the
* subscription oid and the xid of the prepared transaction) for each prepare
* transaction on the subscriber.
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <sys/stat.h>
#include <unistd.h>
#include "access/table.h"
#include "access/tableam.h"
#include "access/twophase.h"
#include "access/xact.h"
#include "access/xlog_internal.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
#include "catalog/partition.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_subscription.h"
#include "catalog/pg_subscription_rel.h"
#include "catalog/pg_tablespace.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "executor/execPartition.h"
#include "executor/nodeModifyTable.h"
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "libpq/pqsignal.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "optimizer/optimizer.h"
#include "pgstat.h"
#include "postmaster/bgworker.h"
#include "postmaster/interrupt.h"
#include "postmaster/postmaster.h"
#include "postmaster/walwriter.h"
#include "replication/decode.h"
#include "replication/logical.h"
#include "replication/logicalproto.h"
#include "replication/logicalrelation.h"
#include "replication/logicalworker.h"
#include "replication/origin.h"
#include "replication/reorderbuffer.h"
#include "replication/snapbuild.h"
#include "replication/walreceiver.h"
#include "replication/worker_internal.h"
#include "rewrite/rewriteHandler.h"
#include "storage/buffile.h"
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "tcop/tcopprot.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/dynahash.h"
#include "utils/datum.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/rls.h"
#include "utils/syscache.h"
#include "utils/timeout.h"
#define NAPTIME_PER_CYCLE 1000 /* max sleep time between cycles (1s) */
typedef struct FlushPosition
{
dlist_node node;
XLogRecPtr local_end;
XLogRecPtr remote_end;
} FlushPosition;
static dlist_head lsn_mapping = DLIST_STATIC_INIT(lsn_mapping);
typedef struct ApplyExecutionData
{
EState *estate; /* executor state, used to track resources */
LogicalRepRelMapEntry *targetRel; /* replication target rel */
ResultRelInfo *targetRelInfo; /* ResultRelInfo for same */
/* These fields are used when the target relation is partitioned: */
ModifyTableState *mtstate; /* dummy ModifyTable state */
PartitionTupleRouting *proute; /* partition routing info */
} ApplyExecutionData;
/* Struct for saving and restoring apply errcontext information */
typedef struct ApplyErrorCallbackArg
{
LogicalRepMsgType command; /* 0 if invalid */
LogicalRepRelMapEntry *rel;
/* Remote node information */
int remote_attnum; /* -1 if invalid */
TransactionId remote_xid;
TimestampTz ts; /* commit, rollback, or prepare timestamp */
} ApplyErrorCallbackArg;
static ApplyErrorCallbackArg apply_error_callback_arg =
{
.command = 0,
.rel = NULL,
.remote_attnum = -1,
.remote_xid = InvalidTransactionId,
.ts = 0,
};
static MemoryContext ApplyMessageContext = NULL;
MemoryContext ApplyContext = NULL;
/* per stream context for streaming transactions */
static MemoryContext LogicalStreamingContext = NULL;
WalReceiverConn *LogRepWorkerWalRcvConn = NULL;
Subscription *MySubscription = NULL;
bool MySubscriptionValid = false;
bool in_remote_transaction = false;
static XLogRecPtr remote_final_lsn = InvalidXLogRecPtr;
/* fields valid only when processing streamed transaction */
static bool in_streamed_transaction = false;
static TransactionId stream_xid = InvalidTransactionId;
/* BufFile handle of the current streaming file */
static BufFile *stream_fd = NULL;
typedef struct SubXactInfo
{
TransactionId xid; /* XID of the subxact */
int fileno; /* file number in the buffile */
off_t offset; /* offset in the file */
} SubXactInfo;
/* Sub-transaction data for the current streaming transaction */
typedef struct ApplySubXactData
{
uint32 nsubxacts; /* number of sub-transactions */
uint32 nsubxacts_max; /* current capacity of subxacts */
TransactionId subxact_last; /* xid of the last sub-transaction */
SubXactInfo *subxacts; /* sub-xact offset in changes file */
} ApplySubXactData;
static ApplySubXactData subxact_data = {0, 0, InvalidTransactionId, NULL};
static inline void subxact_filename(char *path, Oid subid, TransactionId xid);
static inline void changes_filename(char *path, Oid subid, TransactionId xid);
/*
* Information about subtransactions of a given toplevel transaction.
*/
static void subxact_info_write(Oid subid, TransactionId xid);
static void subxact_info_read(Oid subid, TransactionId xid);
static void subxact_info_add(TransactionId xid);
static inline void cleanup_subxact_info(void);
/*
* Serialize and deserialize changes for a toplevel transaction.
*/
static void stream_cleanup_files(Oid subid, TransactionId xid);
static void stream_open_file(Oid subid, TransactionId xid, bool first);
static void stream_write_change(char action, StringInfo s);
static void stream_close_file(void);
static void send_feedback(XLogRecPtr recvpos, bool force, bool requestReply);
static void store_flush_position(XLogRecPtr remote_lsn);
static void maybe_reread_subscription(void);
/* prototype needed because of stream_commit */
static void apply_dispatch(StringInfo s);
static void apply_handle_commit_internal(LogicalRepCommitData *commit_data);
static void apply_handle_insert_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot);
static void apply_handle_update_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot,
LogicalRepTupleData *newtup);
static void apply_handle_delete_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot);
static bool FindReplTupleInLocalRel(EState *estate, Relation localrel,
LogicalRepRelation *remoterel,
TupleTableSlot *remoteslot,
TupleTableSlot **localslot);
static void apply_handle_tuple_routing(ApplyExecutionData *edata,
TupleTableSlot *remoteslot,
LogicalRepTupleData *newtup,
CmdType operation);
/* Compute GID for two_phase transactions */
static void TwoPhaseTransactionGid(Oid subid, TransactionId xid, char *gid, int szgid);
/* Common streaming function to apply all the spooled messages */
static void apply_spooled_messages(TransactionId xid, XLogRecPtr lsn);
/* Functions for apply error callback */
static void apply_error_callback(void *arg);
static inline void set_apply_error_context_xact(TransactionId xid, TimestampTz ts);
static inline void reset_apply_error_context_info(void);
/*
* Should this worker apply changes for given relation.
*
* This is mainly needed for initial relation data sync as that runs in
* separate worker process running in parallel and we need some way to skip
* changes coming to the main apply worker during the sync of a table.
*
* Note we need to do smaller or equals comparison for SYNCDONE state because
* it might hold position of end of initial slot consistent point WAL
* record + 1 (ie start of next record) and next record can be COMMIT of
* transaction we are now processing (which is what we set remote_final_lsn
* to in apply_handle_begin).
*/
static bool
should_apply_changes_for_rel(LogicalRepRelMapEntry *rel)
{
if (am_tablesync_worker())
return MyLogicalRepWorker->relid == rel->localreloid;
else
return (rel->state == SUBREL_STATE_READY ||
(rel->state == SUBREL_STATE_SYNCDONE &&
rel->statelsn <= remote_final_lsn));
}
/*
* Begin one step (one INSERT, UPDATE, etc) of a replication transaction.
*
* Start a transaction, if this is the first step (else we keep using the
* existing transaction).
* Also provide a global snapshot and ensure we run in ApplyMessageContext.
*/
static void
begin_replication_step(void)
{
SetCurrentStatementStartTimestamp();
if (!IsTransactionState())
{
StartTransactionCommand();
maybe_reread_subscription();
}
PushActiveSnapshot(GetTransactionSnapshot());
MemoryContextSwitchTo(ApplyMessageContext);
}
/*
* Finish up one step of a replication transaction.
* Callers of begin_replication_step() must also call this.
*
* We don't close out the transaction here, but we should increment
* the command counter to make the effects of this step visible.
*/
static void
end_replication_step(void)
{
PopActiveSnapshot();
CommandCounterIncrement();
}
/*
* Handle streamed transactions.
*
* If in streaming mode (receiving a block of streamed transaction), we
* simply redirect it to a file for the proper toplevel transaction.
*
* Returns true for streamed transactions, false otherwise (regular mode).
*/
static bool
handle_streamed_transaction(LogicalRepMsgType action, StringInfo s)
{
TransactionId xid;
/* not in streaming mode */
if (!in_streamed_transaction)
return false;
Assert(stream_fd != NULL);
Assert(TransactionIdIsValid(stream_xid));
/*
* We should have received XID of the subxact as the first part of the
* message, so extract it.
*/
xid = pq_getmsgint(s, 4);
if (!TransactionIdIsValid(xid))
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("invalid transaction ID in streamed replication transaction")));
/* Add the new subxact to the array (unless already there). */
subxact_info_add(xid);
/* write the change to the current file */
stream_write_change(action, s);
return true;
}
/*
* Executor state preparation for evaluation of constraint expressions,
* indexes and triggers for the specified relation.
*
* Note that the caller must open and close any indexes to be updated.
*/
static ApplyExecutionData *
create_edata_for_relation(LogicalRepRelMapEntry *rel)
{
ApplyExecutionData *edata;
EState *estate;
RangeTblEntry *rte;
ResultRelInfo *resultRelInfo;
edata = (ApplyExecutionData *) palloc0(sizeof(ApplyExecutionData));
edata->targetRel = rel;
edata->estate = estate = CreateExecutorState();
rte = makeNode(RangeTblEntry);
rte->rtekind = RTE_RELATION;
rte->relid = RelationGetRelid(rel->localrel);
rte->relkind = rel->localrel->rd_rel->relkind;
rte->rellockmode = AccessShareLock;
ExecInitRangeTable(estate, list_make1(rte));
edata->targetRelInfo = resultRelInfo = makeNode(ResultRelInfo);
/*
* Use Relation opened by logicalrep_rel_open() instead of opening it
* again.
*/
InitResultRelInfo(resultRelInfo, rel->localrel, 1, NULL, 0);
/*
* We put the ResultRelInfo in the es_opened_result_relations list, even
* though we don't populate the es_result_relations array. That's a bit
* bogus, but it's enough to make ExecGetTriggerResultRel() find them.
*
* ExecOpenIndices() is not called here either, each execution path doing
* an apply operation being responsible for that.
*/
estate->es_opened_result_relations =
lappend(estate->es_opened_result_relations, resultRelInfo);
estate->es_output_cid = GetCurrentCommandId(true);
/* Prepare to catch AFTER triggers. */
AfterTriggerBeginQuery();
/* other fields of edata remain NULL for now */
return edata;
}
/*
* Finish any operations related to the executor state created by
* create_edata_for_relation().
*/
static void
finish_edata(ApplyExecutionData *edata)
{
EState *estate = edata->estate;
/* Handle any queued AFTER triggers. */
AfterTriggerEndQuery(estate);
/* Shut down tuple routing, if any was done. */
if (edata->proute)
ExecCleanupTupleRouting(edata->mtstate, edata->proute);
/*
* Cleanup. It might seem that we should call ExecCloseResultRelations()
* here, but we intentionally don't. It would close the rel we added to
* es_opened_result_relations above, which is wrong because we took no
* corresponding refcount. We rely on ExecCleanupTupleRouting() to close
* any other relations opened during execution.
*/
ExecResetTupleTable(estate->es_tupleTable, false);
FreeExecutorState(estate);
pfree(edata);
}
/*
* Executes default values for columns for which we can't map to remote
* relation columns.
*
* This allows us to support tables which have more columns on the downstream
* than on the upstream.
*/
static void
slot_fill_defaults(LogicalRepRelMapEntry *rel, EState *estate,
TupleTableSlot *slot)
{
TupleDesc desc = RelationGetDescr(rel->localrel);
int num_phys_attrs = desc->natts;
int i;
int attnum,
num_defaults = 0;
int *defmap;
ExprState **defexprs;
ExprContext *econtext;
econtext = GetPerTupleExprContext(estate);
/* We got all the data via replication, no need to evaluate anything. */
if (num_phys_attrs == rel->remoterel.natts)
return;
defmap = (int *) palloc(num_phys_attrs * sizeof(int));
defexprs = (ExprState **) palloc(num_phys_attrs * sizeof(ExprState *));
Assert(rel->attrmap->maplen == num_phys_attrs);
for (attnum = 0; attnum < num_phys_attrs; attnum++)
{
Expr *defexpr;
if (TupleDescAttr(desc, attnum)->attisdropped || TupleDescAttr(desc, attnum)->attgenerated)
continue;
if (rel->attrmap->attnums[attnum] >= 0)
continue;
defexpr = (Expr *) build_column_default(rel->localrel, attnum + 1);
if (defexpr != NULL)
{
/* Run the expression through planner */
defexpr = expression_planner(defexpr);
/* Initialize executable expression in copycontext */
defexprs[num_defaults] = ExecInitExpr(defexpr, NULL);
defmap[num_defaults] = attnum;
num_defaults++;
}
}
for (i = 0; i < num_defaults; i++)
slot->tts_values[defmap[i]] =
ExecEvalExpr(defexprs[i], econtext, &slot->tts_isnull[defmap[i]]);
}
/*
* Store tuple data into slot.
*
* Incoming data can be either text or binary format.
*/
static void
slot_store_data(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
LogicalRepTupleData *tupleData)
{
int natts = slot->tts_tupleDescriptor->natts;
int i;
ExecClearTuple(slot);
/* Call the "in" function for each non-dropped, non-null attribute */
Assert(natts == rel->attrmap->maplen);
for (i = 0; i < natts; i++)
{
Form_pg_attribute att = TupleDescAttr(slot->tts_tupleDescriptor, i);
int remoteattnum = rel->attrmap->attnums[i];
if (!att->attisdropped && remoteattnum >= 0)
{
StringInfo colvalue = &tupleData->colvalues[remoteattnum];
Assert(remoteattnum < tupleData->ncols);
/* Set attnum for error callback */
apply_error_callback_arg.remote_attnum = remoteattnum;
if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_TEXT)
{
Oid typinput;
Oid typioparam;
getTypeInputInfo(att->atttypid, &typinput, &typioparam);
slot->tts_values[i] =
OidInputFunctionCall(typinput, colvalue->data,
typioparam, att->atttypmod);
slot->tts_isnull[i] = false;
}
else if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_BINARY)
{
Oid typreceive;
Oid typioparam;
/*
* In some code paths we may be asked to re-parse the same
* tuple data. Reset the StringInfo's cursor so that works.
*/
colvalue->cursor = 0;
getTypeBinaryInputInfo(att->atttypid, &typreceive, &typioparam);
slot->tts_values[i] =
OidReceiveFunctionCall(typreceive, colvalue,
typioparam, att->atttypmod);
/* Trouble if it didn't eat the whole buffer */
if (colvalue->cursor != colvalue->len)
ereport(ERROR,
(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
errmsg("incorrect binary data format in logical replication column %d",
remoteattnum + 1)));
slot->tts_isnull[i] = false;
}
else
{
/*
* NULL value from remote. (We don't expect to see
* LOGICALREP_COLUMN_UNCHANGED here, but if we do, treat it as
* NULL.)
*/
slot->tts_values[i] = (Datum) 0;
slot->tts_isnull[i] = true;
}
/* Reset attnum for error callback */
apply_error_callback_arg.remote_attnum = -1;
}
else
{
/*
* We assign NULL to dropped attributes and missing values
* (missing values should be later filled using
* slot_fill_defaults).
*/
slot->tts_values[i] = (Datum) 0;
slot->tts_isnull[i] = true;
}
}
ExecStoreVirtualTuple(slot);
}
/*
* Replace updated columns with data from the LogicalRepTupleData struct.
* This is somewhat similar to heap_modify_tuple but also calls the type
* input functions on the user data.
*
* "slot" is filled with a copy of the tuple in "srcslot", replacing
* columns provided in "tupleData" and leaving others as-is.
*
* Caution: unreplaced pass-by-ref columns in "slot" will point into the
* storage for "srcslot". This is OK for current usage, but someday we may
* need to materialize "slot" at the end to make it independent of "srcslot".
*/
static void
slot_modify_data(TupleTableSlot *slot, TupleTableSlot *srcslot,
LogicalRepRelMapEntry *rel,
LogicalRepTupleData *tupleData)
{
int natts = slot->tts_tupleDescriptor->natts;
int i;
/* We'll fill "slot" with a virtual tuple, so we must start with ... */
ExecClearTuple(slot);
/*
* Copy all the column data from srcslot, so that we'll have valid values
* for unreplaced columns.
*/
Assert(natts == srcslot->tts_tupleDescriptor->natts);
slot_getallattrs(srcslot);
memcpy(slot->tts_values, srcslot->tts_values, natts * sizeof(Datum));
memcpy(slot->tts_isnull, srcslot->tts_isnull, natts * sizeof(bool));
/* Call the "in" function for each replaced attribute */
Assert(natts == rel->attrmap->maplen);
for (i = 0; i < natts; i++)
{
Form_pg_attribute att = TupleDescAttr(slot->tts_tupleDescriptor, i);
int remoteattnum = rel->attrmap->attnums[i];
if (remoteattnum < 0)
continue;
Assert(remoteattnum < tupleData->ncols);
if (tupleData->colstatus[remoteattnum] != LOGICALREP_COLUMN_UNCHANGED)
{
StringInfo colvalue = &tupleData->colvalues[remoteattnum];
/* Set attnum for error callback */
apply_error_callback_arg.remote_attnum = remoteattnum;
if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_TEXT)
{
Oid typinput;
Oid typioparam;
getTypeInputInfo(att->atttypid, &typinput, &typioparam);
slot->tts_values[i] =
OidInputFunctionCall(typinput, colvalue->data,
typioparam, att->atttypmod);
slot->tts_isnull[i] = false;
}
else if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_BINARY)
{
Oid typreceive;
Oid typioparam;
/*
* In some code paths we may be asked to re-parse the same
* tuple data. Reset the StringInfo's cursor so that works.
*/
colvalue->cursor = 0;
getTypeBinaryInputInfo(att->atttypid, &typreceive, &typioparam);
slot->tts_values[i] =
OidReceiveFunctionCall(typreceive, colvalue,
typioparam, att->atttypmod);
/* Trouble if it didn't eat the whole buffer */
if (colvalue->cursor != colvalue->len)
ereport(ERROR,
(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
errmsg("incorrect binary data format in logical replication column %d",
remoteattnum + 1)));
slot->tts_isnull[i] = false;
}
else
{
/* must be LOGICALREP_COLUMN_NULL */
slot->tts_values[i] = (Datum) 0;
slot->tts_isnull[i] = true;
}
/* Reset attnum for error callback */
apply_error_callback_arg.remote_attnum = -1;
}
}
/* And finally, declare that "slot" contains a valid virtual tuple */
ExecStoreVirtualTuple(slot);
}
/*
* Handle BEGIN message.
*/
static void
apply_handle_begin(StringInfo s)
{
LogicalRepBeginData begin_data;
logicalrep_read_begin(s, &begin_data);
set_apply_error_context_xact(begin_data.xid, begin_data.committime);
remote_final_lsn = begin_data.final_lsn;
in_remote_transaction = true;
pgstat_report_activity(STATE_RUNNING, NULL);
}
/*
* Handle COMMIT message.
*
* TODO, support tracking of multiple origins
*/
static void
apply_handle_commit(StringInfo s)
{
LogicalRepCommitData commit_data;
logicalrep_read_commit(s, &commit_data);
if (commit_data.commit_lsn != remote_final_lsn)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("incorrect commit LSN %X/%X in commit message (expected %X/%X)",
LSN_FORMAT_ARGS(commit_data.commit_lsn),
LSN_FORMAT_ARGS(remote_final_lsn))));
apply_handle_commit_internal(&commit_data);
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(commit_data.end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle BEGIN PREPARE message.
*/
static void
apply_handle_begin_prepare(StringInfo s)
{
LogicalRepPreparedTxnData begin_data;
/* Tablesync should never receive prepare. */
if (am_tablesync_worker())
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("tablesync worker received a BEGIN PREPARE message")));
logicalrep_read_begin_prepare(s, &begin_data);
set_apply_error_context_xact(begin_data.xid, begin_data.prepare_time);
remote_final_lsn = begin_data.prepare_lsn;
in_remote_transaction = true;
pgstat_report_activity(STATE_RUNNING, NULL);
}
/*
* Common function to prepare the GID.
*/
static void
apply_handle_prepare_internal(LogicalRepPreparedTxnData *prepare_data)
{
char gid[GIDSIZE];
/*
* Compute unique GID for two_phase transactions. We don't use GID of
* prepared transaction sent by server as that can lead to deadlock when
* we have multiple subscriptions from same node point to publications on
* the same node. See comments atop worker.c
*/
TwoPhaseTransactionGid(MySubscription->oid, prepare_data->xid,
gid, sizeof(gid));
/*
* BeginTransactionBlock is necessary to balance the EndTransactionBlock
* called within the PrepareTransactionBlock below.
*/
BeginTransactionBlock();
CommitTransactionCommand(); /* Completes the preceding Begin command. */
/*
* Update origin state so we can restart streaming from correct position
* in case of crash.
*/
replorigin_session_origin_lsn = prepare_data->end_lsn;
replorigin_session_origin_timestamp = prepare_data->prepare_time;
PrepareTransactionBlock(gid);
}
/*
* Handle PREPARE message.
*/
static void
apply_handle_prepare(StringInfo s)
{
LogicalRepPreparedTxnData prepare_data;
logicalrep_read_prepare(s, &prepare_data);
if (prepare_data.prepare_lsn != remote_final_lsn)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("incorrect prepare LSN %X/%X in prepare message (expected %X/%X)",
LSN_FORMAT_ARGS(prepare_data.prepare_lsn),
LSN_FORMAT_ARGS(remote_final_lsn))));
/*
* Unlike commit, here, we always prepare the transaction even though no
* change has happened in this transaction. It is done this way because at
* commit prepared time, we won't know whether we have skipped preparing a
* transaction because of no change.
*
* XXX, We can optimize such that at commit prepared time, we first check
* whether we have prepared the transaction or not but that doesn't seem
* worthwhile because such cases shouldn't be common.
*/
begin_replication_step();
apply_handle_prepare_internal(&prepare_data);
end_replication_step();
CommitTransactionCommand();
pgstat_report_stat(false);
store_flush_position(prepare_data.end_lsn);
in_remote_transaction = false;
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(prepare_data.end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle a COMMIT PREPARED of a previously PREPARED transaction.
*/
static void
apply_handle_commit_prepared(StringInfo s)
{
LogicalRepCommitPreparedTxnData prepare_data;
char gid[GIDSIZE];
logicalrep_read_commit_prepared(s, &prepare_data);
set_apply_error_context_xact(prepare_data.xid, prepare_data.commit_time);
/* Compute GID for two_phase transactions. */
TwoPhaseTransactionGid(MySubscription->oid, prepare_data.xid,
gid, sizeof(gid));
/* There is no transaction when COMMIT PREPARED is called */
begin_replication_step();
/*
* Update origin state so we can restart streaming from correct position
* in case of crash.
*/
replorigin_session_origin_lsn = prepare_data.end_lsn;
replorigin_session_origin_timestamp = prepare_data.commit_time;
FinishPreparedTransaction(gid, true);
end_replication_step();
CommitTransactionCommand();
pgstat_report_stat(false);
store_flush_position(prepare_data.end_lsn);
in_remote_transaction = false;
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(prepare_data.end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle a ROLLBACK PREPARED of a previously PREPARED TRANSACTION.
*/
static void
apply_handle_rollback_prepared(StringInfo s)
{
LogicalRepRollbackPreparedTxnData rollback_data;
char gid[GIDSIZE];
logicalrep_read_rollback_prepared(s, &rollback_data);
set_apply_error_context_xact(rollback_data.xid, rollback_data.rollback_time);
/* Compute GID for two_phase transactions. */
TwoPhaseTransactionGid(MySubscription->oid, rollback_data.xid,
gid, sizeof(gid));
/*
* It is possible that we haven't received prepare because it occurred
* before walsender reached a consistent point or the two_phase was still
* not enabled by that time, so in such cases, we need to skip rollback
* prepared.
*/
if (LookupGXact(gid, rollback_data.prepare_end_lsn,
rollback_data.prepare_time))
{
/*
* Update origin state so we can restart streaming from correct
* position in case of crash.
*/
replorigin_session_origin_lsn = rollback_data.rollback_end_lsn;
replorigin_session_origin_timestamp = rollback_data.rollback_time;
/* There is no transaction when ABORT/ROLLBACK PREPARED is called */
begin_replication_step();
FinishPreparedTransaction(gid, false);
end_replication_step();
CommitTransactionCommand();
}
pgstat_report_stat(false);
store_flush_position(rollback_data.rollback_end_lsn);
in_remote_transaction = false;
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(rollback_data.rollback_end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle STREAM PREPARE.
*
* Logic is in two parts:
* 1. Replay all the spooled operations
* 2. Mark the transaction as prepared
*/
static void
apply_handle_stream_prepare(StringInfo s)
{
LogicalRepPreparedTxnData prepare_data;
if (in_streamed_transaction)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("STREAM PREPARE message without STREAM STOP")));
/* Tablesync should never receive prepare. */
if (am_tablesync_worker())
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("tablesync worker received a STREAM PREPARE message")));
logicalrep_read_stream_prepare(s, &prepare_data);
set_apply_error_context_xact(prepare_data.xid, prepare_data.prepare_time);
elog(DEBUG1, "received prepare for streamed transaction %u", prepare_data.xid);
/* Replay all the spooled operations. */
apply_spooled_messages(prepare_data.xid, prepare_data.prepare_lsn);
/* Mark the transaction as prepared. */
apply_handle_prepare_internal(&prepare_data);
CommitTransactionCommand();
pgstat_report_stat(false);
store_flush_position(prepare_data.end_lsn);
in_remote_transaction = false;
/* unlink the files with serialized changes and subxact info. */
stream_cleanup_files(MyLogicalRepWorker->subid, prepare_data.xid);
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(prepare_data.end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle ORIGIN message.
*
* TODO, support tracking of multiple origins
*/
static void
apply_handle_origin(StringInfo s)
{
/*
* ORIGIN message can only come inside streaming transaction or inside
* remote transaction and before any actual writes.
*/
if (!in_streamed_transaction &&
(!in_remote_transaction ||
(IsTransactionState() && !am_tablesync_worker())))
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("ORIGIN message sent out of order")));
}
/*
* Handle STREAM START message.
*/
static void
apply_handle_stream_start(StringInfo s)
{
bool first_segment;
if (in_streamed_transaction)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("duplicate STREAM START message")));
/*
* Start a transaction on stream start, this transaction will be committed
* on the stream stop unless it is a tablesync worker in which case it
* will be committed after processing all the messages. We need the
* transaction for handling the buffile, used for serializing the
* streaming data and subxact info.
*/
begin_replication_step();
/* notify handle methods we're processing a remote transaction */
in_streamed_transaction = true;
/* extract XID of the top-level transaction */
stream_xid = logicalrep_read_stream_start(s, &first_segment);
if (!TransactionIdIsValid(stream_xid))
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("invalid transaction ID in streamed replication transaction")));
set_apply_error_context_xact(stream_xid, 0);
/*
* Initialize the worker's stream_fileset if we haven't yet. This will be
* used for the entire duration of the worker so create it in a permanent
* context. We create this on the very first streaming message from any
* transaction and then use it for this and other streaming transactions.
* Now, we could create a fileset at the start of the worker as well but
* then we won't be sure that it will ever be used.
*/
if (MyLogicalRepWorker->stream_fileset == NULL)
{
MemoryContext oldctx;
oldctx = MemoryContextSwitchTo(ApplyContext);
MyLogicalRepWorker->stream_fileset = palloc(sizeof(FileSet));
FileSetInit(MyLogicalRepWorker->stream_fileset);
MemoryContextSwitchTo(oldctx);
}
/* open the spool file for this transaction */
stream_open_file(MyLogicalRepWorker->subid, stream_xid, first_segment);
/* if this is not the first segment, open existing subxact file */
if (!first_segment)
subxact_info_read(MyLogicalRepWorker->subid, stream_xid);
pgstat_report_activity(STATE_RUNNING, NULL);
end_replication_step();
}
/*
* Handle STREAM STOP message.
*/
static void
apply_handle_stream_stop(StringInfo s)
{
if (!in_streamed_transaction)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("STREAM STOP message without STREAM START")));
/*
* Close the file with serialized changes, and serialize information about
* subxacts for the toplevel transaction.
*/
subxact_info_write(MyLogicalRepWorker->subid, stream_xid);
stream_close_file();
/* We must be in a valid transaction state */
Assert(IsTransactionState());
/* Commit the per-stream transaction */
CommitTransactionCommand();
in_streamed_transaction = false;
/* Reset per-stream context */
MemoryContextReset(LogicalStreamingContext);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Handle STREAM abort message.
*/
static void
apply_handle_stream_abort(StringInfo s)
{
TransactionId xid;
TransactionId subxid;
if (in_streamed_transaction)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("STREAM ABORT message without STREAM STOP")));
logicalrep_read_stream_abort(s, &xid, &subxid);
/*
* If the two XIDs are the same, it's in fact abort of toplevel xact, so
* just delete the files with serialized info.
*/
if (xid == subxid)
{
set_apply_error_context_xact(xid, 0);
stream_cleanup_files(MyLogicalRepWorker->subid, xid);
}
else
{
/*
* OK, so it's a subxact. We need to read the subxact file for the
* toplevel transaction, determine the offset tracked for the subxact,
* and truncate the file with changes. We also remove the subxacts
* with higher offsets (or rather higher XIDs).
*
* We intentionally scan the array from the tail, because we're likely
* aborting a change for the most recent subtransactions.
*
* We can't use the binary search here as subxact XIDs won't
* necessarily arrive in sorted order, consider the case where we have
* released the savepoint for multiple subtransactions and then
* performed rollback to savepoint for one of the earlier
* sub-transaction.
*/
int64 i;
int64 subidx;
BufFile *fd;
bool found = false;
char path[MAXPGPATH];
set_apply_error_context_xact(subxid, 0);
subidx = -1;
begin_replication_step();
subxact_info_read(MyLogicalRepWorker->subid, xid);
for (i = subxact_data.nsubxacts; i > 0; i--)
{
if (subxact_data.subxacts[i - 1].xid == subxid)
{
subidx = (i - 1);
found = true;
break;
}
}
/*
* If it's an empty sub-transaction then we will not find the subxid
* here so just cleanup the subxact info and return.
*/
if (!found)
{
/* Cleanup the subxact info */
cleanup_subxact_info();
end_replication_step();
CommitTransactionCommand();
reset_apply_error_context_info();
return;
}
/* open the changes file */
changes_filename(path, MyLogicalRepWorker->subid, xid);
fd = BufFileOpenFileSet(MyLogicalRepWorker->stream_fileset, path,
O_RDWR, false);
/* OK, truncate the file at the right offset */
BufFileTruncateFileSet(fd, subxact_data.subxacts[subidx].fileno,
subxact_data.subxacts[subidx].offset);
BufFileClose(fd);
/* discard the subxacts added later */
subxact_data.nsubxacts = subidx;
/* write the updated subxact list */
subxact_info_write(MyLogicalRepWorker->subid, xid);
end_replication_step();
CommitTransactionCommand();
}
reset_apply_error_context_info();
}
/*
* Common spoolfile processing.
*/
static void
apply_spooled_messages(TransactionId xid, XLogRecPtr lsn)
{
StringInfoData s2;
int nchanges;
char path[MAXPGPATH];
char *buffer = NULL;
MemoryContext oldcxt;
BufFile *fd;
/* Make sure we have an open transaction */
begin_replication_step();
/*
* Allocate file handle and memory required to process all the messages in
* TopTransactionContext to avoid them getting reset after each message is
* processed.
*/
oldcxt = MemoryContextSwitchTo(TopTransactionContext);
/* Open the spool file for the committed/prepared transaction */
changes_filename(path, MyLogicalRepWorker->subid, xid);
elog(DEBUG1, "replaying changes from file \"%s\"", path);
fd = BufFileOpenFileSet(MyLogicalRepWorker->stream_fileset, path, O_RDONLY,
false);
buffer = palloc(BLCKSZ);
initStringInfo(&s2);
MemoryContextSwitchTo(oldcxt);
remote_final_lsn = lsn;
/*
* Make sure the handle apply_dispatch methods are aware we're in a remote
* transaction.
*/
in_remote_transaction = true;
pgstat_report_activity(STATE_RUNNING, NULL);
end_replication_step();
/*
* Read the entries one by one and pass them through the same logic as in
* apply_dispatch.
*/
nchanges = 0;
while (true)
{
int nbytes;
int len;
CHECK_FOR_INTERRUPTS();
/* read length of the on-disk record */
nbytes = BufFileRead(fd, &len, sizeof(len));
/* have we reached end of the file? */
if (nbytes == 0)
break;
/* do we have a correct length? */
if (nbytes != sizeof(len))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from streaming transaction's changes file \"%s\": %m",
path)));
if (len <= 0)
elog(ERROR, "incorrect length %d in streaming transaction's changes file \"%s\"",
len, path);
/* make sure we have sufficiently large buffer */
buffer = repalloc(buffer, len);
/* and finally read the data into the buffer */
if (BufFileRead(fd, buffer, len) != len)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from streaming transaction's changes file \"%s\": %m",
path)));
/* copy the buffer to the stringinfo and call apply_dispatch */
resetStringInfo(&s2);
appendBinaryStringInfo(&s2, buffer, len);
/* Ensure we are reading the data into our memory context. */
oldcxt = MemoryContextSwitchTo(ApplyMessageContext);
apply_dispatch(&s2);
MemoryContextReset(ApplyMessageContext);
MemoryContextSwitchTo(oldcxt);
nchanges++;
if (nchanges % 1000 == 0)
elog(DEBUG1, "replayed %d changes from file \"%s\"",
nchanges, path);
}
BufFileClose(fd);
pfree(buffer);
pfree(s2.data);
elog(DEBUG1, "replayed %d (all) changes from file \"%s\"",
nchanges, path);
return;
}
/*
* Handle STREAM COMMIT message.
*/
static void
apply_handle_stream_commit(StringInfo s)
{
TransactionId xid;
LogicalRepCommitData commit_data;
if (in_streamed_transaction)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("STREAM COMMIT message without STREAM STOP")));
xid = logicalrep_read_stream_commit(s, &commit_data);
set_apply_error_context_xact(xid, commit_data.committime);
elog(DEBUG1, "received commit for streamed transaction %u", xid);
apply_spooled_messages(xid, commit_data.commit_lsn);
apply_handle_commit_internal(&commit_data);
/* unlink the files with serialized changes and subxact info */
stream_cleanup_files(MyLogicalRepWorker->subid, xid);
/* Process any tables that are being synchronized in parallel. */
process_syncing_tables(commit_data.end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
reset_apply_error_context_info();
}
/*
* Helper function for apply_handle_commit and apply_handle_stream_commit.
*/
static void
apply_handle_commit_internal(LogicalRepCommitData *commit_data)
{
if (IsTransactionState())
{
/*
* Update origin state so we can restart streaming from correct
* position in case of crash.
*/
replorigin_session_origin_lsn = commit_data->end_lsn;
replorigin_session_origin_timestamp = commit_data->committime;
CommitTransactionCommand();
pgstat_report_stat(false);
store_flush_position(commit_data->end_lsn);
}
else
{
/* Process any invalidation messages that might have accumulated. */
AcceptInvalidationMessages();
maybe_reread_subscription();
}
in_remote_transaction = false;
}
/*
* Handle RELATION message.
*
* Note we don't do validation against local schema here. The validation
* against local schema is postponed until first change for given relation
* comes as we only care about it when applying changes for it anyway and we
* do less locking this way.
*/
static void
apply_handle_relation(StringInfo s)
{
LogicalRepRelation *rel;
if (handle_streamed_transaction(LOGICAL_REP_MSG_RELATION, s))
return;
rel = logicalrep_read_rel(s);
logicalrep_relmap_update(rel);
}
/*
* Handle TYPE message.
*
* This implementation pays no attention to TYPE messages; we expect the user
* to have set things up so that the incoming data is acceptable to the input
* functions for the locally subscribed tables. Hence, we just read and
* discard the message.
*/
static void
apply_handle_type(StringInfo s)
{
LogicalRepTyp typ;
if (handle_streamed_transaction(LOGICAL_REP_MSG_TYPE, s))
return;
logicalrep_read_typ(s, &typ);
}
/*
* Get replica identity index or if it is not defined a primary key.
*
* If neither is defined, returns InvalidOid
*/
static Oid
GetRelationIdentityOrPK(Relation rel)
{
Oid idxoid;
idxoid = RelationGetReplicaIndex(rel);
if (!OidIsValid(idxoid))
idxoid = RelationGetPrimaryKeyIndex(rel);
return idxoid;
}
/*
* Check that we (the subscription owner) have sufficient privileges on the
* target relation to perform the given operation.
*/
static void
TargetPrivilegesCheck(Relation rel, AclMode mode)
{
Oid relid;
AclResult aclresult;
relid = RelationGetRelid(rel);
aclresult = pg_class_aclcheck(relid, GetUserId(), mode);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult,
get_relkind_objtype(rel->rd_rel->relkind),
get_rel_name(relid));
/*
* We lack the infrastructure to honor RLS policies. It might be possible
* to add such infrastructure here, but tablesync workers lack it, too, so
* we don't bother. RLS does not ordinarily apply to TRUNCATE commands,
* but it seems dangerous to replicate a TRUNCATE and then refuse to
* replicate subsequent INSERTs, so we forbid all commands the same.
*/
if (check_enable_rls(relid, InvalidOid, false) == RLS_ENABLED)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("\"%s\" cannot replicate into relation with row-level security enabled: \"%s\"",
GetUserNameFromId(GetUserId(), true),
RelationGetRelationName(rel))));
}
/*
* Handle INSERT message.
*/
static void
apply_handle_insert(StringInfo s)
{
LogicalRepRelMapEntry *rel;
LogicalRepTupleData newtup;
LogicalRepRelId relid;
ApplyExecutionData *edata;
EState *estate;
TupleTableSlot *remoteslot;
MemoryContext oldctx;
if (handle_streamed_transaction(LOGICAL_REP_MSG_INSERT, s))
return;
begin_replication_step();
relid = logicalrep_read_insert(s, &newtup);
rel = logicalrep_rel_open(relid, RowExclusiveLock);
if (!should_apply_changes_for_rel(rel))
{
/*
* The relation can't become interesting in the middle of the
* transaction so it's safe to unlock it.
*/
logicalrep_rel_close(rel, RowExclusiveLock);
end_replication_step();
return;
}
/* Set relation for error callback */
apply_error_callback_arg.rel = rel;
/* Initialize the executor state. */
edata = create_edata_for_relation(rel);
estate = edata->estate;
remoteslot = ExecInitExtraTupleSlot(estate,
RelationGetDescr(rel->localrel),
&TTSOpsVirtual);
/* Process and store remote tuple in the slot */
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
slot_store_data(remoteslot, rel, &newtup);
slot_fill_defaults(rel, estate, remoteslot);
MemoryContextSwitchTo(oldctx);
/* For a partitioned table, insert the tuple into a partition. */
if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
apply_handle_tuple_routing(edata,
remoteslot, NULL, CMD_INSERT);
else
apply_handle_insert_internal(edata, edata->targetRelInfo,
remoteslot);
finish_edata(edata);
/* Reset relation for error callback */
apply_error_callback_arg.rel = NULL;
logicalrep_rel_close(rel, NoLock);
end_replication_step();
}
/*
* Workhorse for apply_handle_insert()
* relinfo is for the relation we're actually inserting into
* (could be a child partition of edata->targetRelInfo)
*/
static void
apply_handle_insert_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot)
{
EState *estate = edata->estate;
/* We must open indexes here. */
ExecOpenIndices(relinfo, false);
/* Do the insert. */
TargetPrivilegesCheck(relinfo->ri_RelationDesc, ACL_INSERT);
ExecSimpleRelationInsert(relinfo, estate, remoteslot);
/* Cleanup. */
ExecCloseIndices(relinfo);
}
/*
* Check if the logical replication relation is updatable and throw
* appropriate error if it isn't.
*/
static void
check_relation_updatable(LogicalRepRelMapEntry *rel)
{
/* Updatable, no error. */
if (rel->updatable)
return;
/*
* We are in error mode so it's fine this is somewhat slow. It's better to
* give user correct error.
*/
if (OidIsValid(GetRelationIdentityOrPK(rel->localrel)))
{
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("publisher did not send replica identity column "
"expected by the logical replication target relation \"%s.%s\"",
rel->remoterel.nspname, rel->remoterel.relname)));
}
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("logical replication target relation \"%s.%s\" has "
"neither REPLICA IDENTITY index nor PRIMARY "
"KEY and published relation does not have "
"REPLICA IDENTITY FULL",
rel->remoterel.nspname, rel->remoterel.relname)));
}
/*
* Handle UPDATE message.
*
* TODO: FDW support
*/
static void
apply_handle_update(StringInfo s)
{
LogicalRepRelMapEntry *rel;
LogicalRepRelId relid;
ApplyExecutionData *edata;
EState *estate;
LogicalRepTupleData oldtup;
LogicalRepTupleData newtup;
bool has_oldtup;
TupleTableSlot *remoteslot;
RangeTblEntry *target_rte;
MemoryContext oldctx;
if (handle_streamed_transaction(LOGICAL_REP_MSG_UPDATE, s))
return;
begin_replication_step();
relid = logicalrep_read_update(s, &has_oldtup, &oldtup,
&newtup);
rel = logicalrep_rel_open(relid, RowExclusiveLock);
if (!should_apply_changes_for_rel(rel))
{
/*
* The relation can't become interesting in the middle of the
* transaction so it's safe to unlock it.
*/
logicalrep_rel_close(rel, RowExclusiveLock);
end_replication_step();
return;
}
/* Set relation for error callback */
apply_error_callback_arg.rel = rel;
/* Check if we can do the update. */
check_relation_updatable(rel);
/* Initialize the executor state. */
edata = create_edata_for_relation(rel);
estate = edata->estate;
remoteslot = ExecInitExtraTupleSlot(estate,
RelationGetDescr(rel->localrel),
&TTSOpsVirtual);
/*
* Populate updatedCols so that per-column triggers can fire, and so
* executor can correctly pass down indexUnchanged hint. This could
* include more columns than were actually changed on the publisher
* because the logical replication protocol doesn't contain that
* information. But it would for example exclude columns that only exist
* on the subscriber, since we are not touching those.
*/
target_rte = list_nth(estate->es_range_table, 0);
for (int i = 0; i < remoteslot->tts_tupleDescriptor->natts; i++)
{
Form_pg_attribute att = TupleDescAttr(remoteslot->tts_tupleDescriptor, i);
int remoteattnum = rel->attrmap->attnums[i];
if (!att->attisdropped && remoteattnum >= 0)
{
Assert(remoteattnum < newtup.ncols);
if (newtup.colstatus[remoteattnum] != LOGICALREP_COLUMN_UNCHANGED)
target_rte->updatedCols =
bms_add_member(target_rte->updatedCols,
i + 1 - FirstLowInvalidHeapAttributeNumber);
}
}
/* Also populate extraUpdatedCols, in case we have generated columns */
fill_extraUpdatedCols(target_rte, rel->localrel);
/* Build the search tuple. */
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
slot_store_data(remoteslot, rel,
has_oldtup ? &oldtup : &newtup);
MemoryContextSwitchTo(oldctx);
/* For a partitioned table, apply update to correct partition. */
if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
apply_handle_tuple_routing(edata,
remoteslot, &newtup, CMD_UPDATE);
else
apply_handle_update_internal(edata, edata->targetRelInfo,
remoteslot, &newtup);
finish_edata(edata);
/* Reset relation for error callback */
apply_error_callback_arg.rel = NULL;
logicalrep_rel_close(rel, NoLock);
end_replication_step();
}
/*
* Workhorse for apply_handle_update()
* relinfo is for the relation we're actually updating in
* (could be a child partition of edata->targetRelInfo)
*/
static void
apply_handle_update_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot,
LogicalRepTupleData *newtup)
{
EState *estate = edata->estate;
LogicalRepRelMapEntry *relmapentry = edata->targetRel;
Relation localrel = relinfo->ri_RelationDesc;
EPQState epqstate;
TupleTableSlot *localslot;
bool found;
MemoryContext oldctx;
EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
ExecOpenIndices(relinfo, false);
found = FindReplTupleInLocalRel(estate, localrel,
&relmapentry->remoterel,
remoteslot, &localslot);
ExecClearTuple(remoteslot);
/*
* Tuple found.
*
* Note this will fail if there are other conflicting unique indexes.
*/
if (found)
{
/* Process and store remote tuple in the slot */
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
slot_modify_data(remoteslot, localslot, relmapentry, newtup);
MemoryContextSwitchTo(oldctx);
EvalPlanQualSetSlot(&epqstate, remoteslot);
/* Do the actual update. */
TargetPrivilegesCheck(relinfo->ri_RelationDesc, ACL_UPDATE);
ExecSimpleRelationUpdate(relinfo, estate, &epqstate, localslot,
remoteslot);
}
else
{
/*
* The tuple to be updated could not be found. Do nothing except for
* emitting a log message.
*
* XXX should this be promoted to ereport(LOG) perhaps?
*/
elog(DEBUG1,
"logical replication did not find row to be updated "
"in replication target relation \"%s\"",
RelationGetRelationName(localrel));
}
/* Cleanup. */
ExecCloseIndices(relinfo);
EvalPlanQualEnd(&epqstate);
}
/*
* Handle DELETE message.
*
* TODO: FDW support
*/
static void
apply_handle_delete(StringInfo s)
{
LogicalRepRelMapEntry *rel;
LogicalRepTupleData oldtup;
LogicalRepRelId relid;
ApplyExecutionData *edata;
EState *estate;
TupleTableSlot *remoteslot;
MemoryContext oldctx;
if (handle_streamed_transaction(LOGICAL_REP_MSG_DELETE, s))
return;
begin_replication_step();
relid = logicalrep_read_delete(s, &oldtup);
rel = logicalrep_rel_open(relid, RowExclusiveLock);
if (!should_apply_changes_for_rel(rel))
{
/*
* The relation can't become interesting in the middle of the
* transaction so it's safe to unlock it.
*/
logicalrep_rel_close(rel, RowExclusiveLock);
end_replication_step();
return;
}
/* Set relation for error callback */
apply_error_callback_arg.rel = rel;
/* Check if we can do the delete. */
check_relation_updatable(rel);
/* Initialize the executor state. */
edata = create_edata_for_relation(rel);
estate = edata->estate;
remoteslot = ExecInitExtraTupleSlot(estate,
RelationGetDescr(rel->localrel),
&TTSOpsVirtual);
/* Build the search tuple. */
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
slot_store_data(remoteslot, rel, &oldtup);
MemoryContextSwitchTo(oldctx);
/* For a partitioned table, apply delete to correct partition. */
if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
apply_handle_tuple_routing(edata,
remoteslot, NULL, CMD_DELETE);
else
apply_handle_delete_internal(edata, edata->targetRelInfo,
remoteslot);
finish_edata(edata);
/* Reset relation for error callback */
apply_error_callback_arg.rel = NULL;
logicalrep_rel_close(rel, NoLock);
end_replication_step();
}
/*
* Workhorse for apply_handle_delete()
* relinfo is for the relation we're actually deleting from
* (could be a child partition of edata->targetRelInfo)
*/
static void
apply_handle_delete_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
TupleTableSlot *remoteslot)
{
EState *estate = edata->estate;
Relation localrel = relinfo->ri_RelationDesc;
LogicalRepRelation *remoterel = &edata->targetRel->remoterel;
EPQState epqstate;
TupleTableSlot *localslot;
bool found;
EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
ExecOpenIndices(relinfo, false);
found = FindReplTupleInLocalRel(estate, localrel, remoterel,
remoteslot, &localslot);
/* If found delete it. */
if (found)
{
EvalPlanQualSetSlot(&epqstate, localslot);
/* Do the actual delete. */
TargetPrivilegesCheck(relinfo->ri_RelationDesc, ACL_DELETE);
ExecSimpleRelationDelete(relinfo, estate, &epqstate, localslot);
}
else
{
/*
* The tuple to be deleted could not be found. Do nothing except for
* emitting a log message.
*
* XXX should this be promoted to ereport(LOG) perhaps?
*/
elog(DEBUG1,
"logical replication did not find row to be deleted "
"in replication target relation \"%s\"",
RelationGetRelationName(localrel));
}
/* Cleanup. */
ExecCloseIndices(relinfo);
EvalPlanQualEnd(&epqstate);
}
/*
* Try to find a tuple received from the publication side (in 'remoteslot') in
* the corresponding local relation using either replica identity index,
* primary key or if needed, sequential scan.
*
* Local tuple, if found, is returned in '*localslot'.
*/
static bool
FindReplTupleInLocalRel(EState *estate, Relation localrel,
LogicalRepRelation *remoterel,
TupleTableSlot *remoteslot,
TupleTableSlot **localslot)
{
Oid idxoid;
bool found;
/*
* Regardless of the top-level operation, we're performing a read here, so
* check for SELECT privileges.
*/
TargetPrivilegesCheck(localrel, ACL_SELECT);
*localslot = table_slot_create(localrel, &estate->es_tupleTable);
idxoid = GetRelationIdentityOrPK(localrel);
Assert(OidIsValid(idxoid) ||
(remoterel->replident == REPLICA_IDENTITY_FULL));
if (OidIsValid(idxoid))
found = RelationFindReplTupleByIndex(localrel, idxoid,
LockTupleExclusive,
remoteslot, *localslot);
else
found = RelationFindReplTupleSeq(localrel, LockTupleExclusive,
remoteslot, *localslot);
return found;
}
/*
* This handles insert, update, delete on a partitioned table.
*/
static void
apply_handle_tuple_routing(ApplyExecutionData *edata,
TupleTableSlot *remoteslot,
LogicalRepTupleData *newtup,
CmdType operation)
{
EState *estate = edata->estate;
LogicalRepRelMapEntry *relmapentry = edata->targetRel;
ResultRelInfo *relinfo = edata->targetRelInfo;
Relation parentrel = relinfo->ri_RelationDesc;
ModifyTableState *mtstate;
PartitionTupleRouting *proute;
ResultRelInfo *partrelinfo;
Relation partrel;
TupleTableSlot *remoteslot_part;
TupleConversionMap *map;
MemoryContext oldctx;
/* ModifyTableState is needed for ExecFindPartition(). */
edata->mtstate = mtstate = makeNode(ModifyTableState);
mtstate->ps.plan = NULL;
mtstate->ps.state = estate;
mtstate->operation = operation;
mtstate->resultRelInfo = relinfo;
/* ... as is PartitionTupleRouting. */
edata->proute = proute = ExecSetupPartitionTupleRouting(estate, parentrel);
/*
* Find the partition to which the "search tuple" belongs.
*/
Assert(remoteslot != NULL);
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
partrelinfo = ExecFindPartition(mtstate, relinfo, proute,
remoteslot, estate);
Assert(partrelinfo != NULL);
partrel = partrelinfo->ri_RelationDesc;
/*
* To perform any of the operations below, the tuple must match the
* partition's rowtype. Convert if needed or just copy, using a dedicated
* slot to store the tuple in any case.
*/
remoteslot_part = partrelinfo->ri_PartitionTupleSlot;
if (remoteslot_part == NULL)
remoteslot_part = table_slot_create(partrel, &estate->es_tupleTable);
map = partrelinfo->ri_RootToPartitionMap;
if (map != NULL)
remoteslot_part = execute_attr_map_slot(map->attrMap, remoteslot,
remoteslot_part);
else
{
remoteslot_part = ExecCopySlot(remoteslot_part, remoteslot);
slot_getallattrs(remoteslot_part);
}
MemoryContextSwitchTo(oldctx);
switch (operation)
{
case CMD_INSERT:
apply_handle_insert_internal(edata, partrelinfo,
remoteslot_part);
break;
case CMD_DELETE:
apply_handle_delete_internal(edata, partrelinfo,
remoteslot_part);
break;
case CMD_UPDATE:
/*
* For UPDATE, depending on whether or not the updated tuple
* satisfies the partition's constraint, perform a simple UPDATE
* of the partition or move the updated tuple into a different
* suitable partition.
*/
{
AttrMap *attrmap = map ? map->attrMap : NULL;
LogicalRepRelMapEntry *part_entry;
TupleTableSlot *localslot;
ResultRelInfo *partrelinfo_new;
bool found;
part_entry = logicalrep_partition_open(relmapentry, partrel,
attrmap);
/* Get the matching local tuple from the partition. */
found = FindReplTupleInLocalRel(estate, partrel,
&part_entry->remoterel,
remoteslot_part, &localslot);
if (!found)
{
/*
* The tuple to be updated could not be found. Do nothing
* except for emitting a log message.
*
* XXX should this be promoted to ereport(LOG) perhaps?
*/
elog(DEBUG1,
"logical replication did not find row to be updated "
"in replication target relation's partition \"%s\"",
RelationGetRelationName(partrel));
return;
}
/*
* Apply the update to the local tuple, putting the result in
* remoteslot_part.
*/
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
slot_modify_data(remoteslot_part, localslot, part_entry,
newtup);
MemoryContextSwitchTo(oldctx);
/*
* Does the updated tuple still satisfy the current
* partition's constraint?
*/
if (!partrel->rd_rel->relispartition ||
ExecPartitionCheck(partrelinfo, remoteslot_part, estate,
false))
{
/*
* Yes, so simply UPDATE the partition. We don't call
* apply_handle_update_internal() here, which would
* normally do the following work, to avoid repeating some
* work already done above to find the local tuple in the
* partition.
*/
EPQState epqstate;
EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
ExecOpenIndices(partrelinfo, false);
EvalPlanQualSetSlot(&epqstate, remoteslot_part);
TargetPrivilegesCheck(partrelinfo->ri_RelationDesc,
ACL_UPDATE);
ExecSimpleRelationUpdate(partrelinfo, estate, &epqstate,
localslot, remoteslot_part);
ExecCloseIndices(partrelinfo);
EvalPlanQualEnd(&epqstate);
}
else
{
/* Move the tuple into the new partition. */
/*
* New partition will be found using tuple routing, which
* can only occur via the parent table. We might need to
* convert the tuple to the parent's rowtype. Note that
* this is the tuple found in the partition, not the
* original search tuple received by this function.
*/
if (map)
{
TupleConversionMap *PartitionToRootMap =
convert_tuples_by_name(RelationGetDescr(partrel),
RelationGetDescr(parentrel));
remoteslot =
execute_attr_map_slot(PartitionToRootMap->attrMap,
remoteslot_part, remoteslot);
}
else
{
remoteslot = ExecCopySlot(remoteslot, remoteslot_part);
slot_getallattrs(remoteslot);
}
/* Find the new partition. */
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
partrelinfo_new = ExecFindPartition(mtstate, relinfo,
proute, remoteslot,
estate);
MemoryContextSwitchTo(oldctx);
Assert(partrelinfo_new != partrelinfo);
/* DELETE old tuple found in the old partition. */
apply_handle_delete_internal(edata, partrelinfo,
localslot);
/* INSERT new tuple into the new partition. */
/*
* Convert the replacement tuple to match the destination
* partition rowtype.
*/
oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
partrel = partrelinfo_new->ri_RelationDesc;
remoteslot_part = partrelinfo_new->ri_PartitionTupleSlot;
if (remoteslot_part == NULL)
remoteslot_part = table_slot_create(partrel,
&estate->es_tupleTable);
map = partrelinfo_new->ri_RootToPartitionMap;
if (map != NULL)
{
remoteslot_part = execute_attr_map_slot(map->attrMap,
remoteslot,
remoteslot_part);
}
else
{
remoteslot_part = ExecCopySlot(remoteslot_part,
remoteslot);
slot_getallattrs(remoteslot);
}
MemoryContextSwitchTo(oldctx);
apply_handle_insert_internal(edata, partrelinfo_new,
remoteslot_part);
}
}
break;
default:
elog(ERROR, "unrecognized CmdType: %d", (int) operation);
break;
}
}
/*
* Handle TRUNCATE message.
*
* TODO: FDW support
*/
static void
apply_handle_truncate(StringInfo s)
{
bool cascade = false;
bool restart_seqs = false;
List *remote_relids = NIL;
List *remote_rels = NIL;
List *rels = NIL;
List *part_rels = NIL;
List *relids = NIL;
List *relids_logged = NIL;
ListCell *lc;
LOCKMODE lockmode = AccessExclusiveLock;
if (handle_streamed_transaction(LOGICAL_REP_MSG_TRUNCATE, s))
return;
begin_replication_step();
remote_relids = logicalrep_read_truncate(s, &cascade, &restart_seqs);
foreach(lc, remote_relids)
{
LogicalRepRelId relid = lfirst_oid(lc);
LogicalRepRelMapEntry *rel;
rel = logicalrep_rel_open(relid, lockmode);
if (!should_apply_changes_for_rel(rel))
{
/*
* The relation can't become interesting in the middle of the
* transaction so it's safe to unlock it.
*/
logicalrep_rel_close(rel, lockmode);
continue;
}
remote_rels = lappend(remote_rels, rel);
TargetPrivilegesCheck(rel->localrel, ACL_TRUNCATE);
rels = lappend(rels, rel->localrel);
relids = lappend_oid(relids, rel->localreloid);
if (RelationIsLogicallyLogged(rel->localrel))
relids_logged = lappend_oid(relids_logged, rel->localreloid);
/*
* Truncate partitions if we got a message to truncate a partitioned
* table.
*/
if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
{
ListCell *child;
List *children = find_all_inheritors(rel->localreloid,
lockmode,
NULL);
foreach(child, children)
{
Oid childrelid = lfirst_oid(child);
Relation childrel;
if (list_member_oid(relids, childrelid))
continue;
/* find_all_inheritors already got lock */
childrel = table_open(childrelid, NoLock);
/*
* Ignore temp tables of other backends. See similar code in
* ExecuteTruncate().
*/
if (RELATION_IS_OTHER_TEMP(childrel))
{
table_close(childrel, lockmode);
continue;
}
TargetPrivilegesCheck(childrel, ACL_TRUNCATE);
rels = lappend(rels, childrel);
part_rels = lappend(part_rels, childrel);
relids = lappend_oid(relids, childrelid);
/* Log this relation only if needed for logical decoding */
if (RelationIsLogicallyLogged(childrel))
relids_logged = lappend_oid(relids_logged, childrelid);
}
}
}
/*
* Even if we used CASCADE on the upstream primary we explicitly default
* to replaying changes without further cascading. This might be later
* changeable with a user specified option.
*/
ExecuteTruncateGuts(rels,
relids,
relids_logged,
DROP_RESTRICT,
restart_seqs);
foreach(lc, remote_rels)
{
LogicalRepRelMapEntry *rel = lfirst(lc);
logicalrep_rel_close(rel, NoLock);
}
foreach(lc, part_rels)
{
Relation rel = lfirst(lc);
table_close(rel, NoLock);
}
end_replication_step();
}
/*
* Logical replication protocol message dispatcher.
*/
static void
apply_dispatch(StringInfo s)
{
LogicalRepMsgType action = pq_getmsgbyte(s);
LogicalRepMsgType saved_command;
/*
* Set the current command being applied. Since this function can be
* called recursively when applying spooled changes, save the current
* command.
*/
saved_command = apply_error_callback_arg.command;
apply_error_callback_arg.command = action;
switch (action)
{
case LOGICAL_REP_MSG_BEGIN:
apply_handle_begin(s);
break;
case LOGICAL_REP_MSG_COMMIT:
apply_handle_commit(s);
break;
case LOGICAL_REP_MSG_INSERT:
apply_handle_insert(s);
break;
case LOGICAL_REP_MSG_UPDATE:
apply_handle_update(s);
break;
case LOGICAL_REP_MSG_DELETE:
apply_handle_delete(s);
break;
case LOGICAL_REP_MSG_TRUNCATE:
apply_handle_truncate(s);
break;
case LOGICAL_REP_MSG_RELATION:
apply_handle_relation(s);
break;
case LOGICAL_REP_MSG_TYPE:
apply_handle_type(s);
break;
case LOGICAL_REP_MSG_ORIGIN:
apply_handle_origin(s);
break;
case LOGICAL_REP_MSG_MESSAGE:
/*
* Logical replication does not use generic logical messages yet.
* Although, it could be used by other applications that use this
* output plugin.
*/
break;
case LOGICAL_REP_MSG_STREAM_START:
apply_handle_stream_start(s);
break;
case LOGICAL_REP_MSG_STREAM_STOP:
apply_handle_stream_stop(s);
break;
case LOGICAL_REP_MSG_STREAM_ABORT:
apply_handle_stream_abort(s);
break;
case LOGICAL_REP_MSG_STREAM_COMMIT:
apply_handle_stream_commit(s);
break;
case LOGICAL_REP_MSG_BEGIN_PREPARE:
apply_handle_begin_prepare(s);
break;
case LOGICAL_REP_MSG_PREPARE:
apply_handle_prepare(s);
break;
case LOGICAL_REP_MSG_COMMIT_PREPARED:
apply_handle_commit_prepared(s);
break;
case LOGICAL_REP_MSG_ROLLBACK_PREPARED:
apply_handle_rollback_prepared(s);
break;
case LOGICAL_REP_MSG_STREAM_PREPARE:
apply_handle_stream_prepare(s);
break;
default:
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("invalid logical replication message type \"%c\"", action)));
}
/* Reset the current command */
apply_error_callback_arg.command = saved_command;
}
/*
* Figure out which write/flush positions to report to the walsender process.
*
* We can't simply report back the last LSN the walsender sent us because the
* local transaction might not yet be flushed to disk locally. Instead we
* build a list that associates local with remote LSNs for every commit. When
* reporting back the flush position to the sender we iterate that list and
* check which entries on it are already locally flushed. Those we can report
* as having been flushed.
*
* The have_pending_txes is true if there are outstanding transactions that
* need to be flushed.
*/
static void
get_flush_position(XLogRecPtr *write, XLogRecPtr *flush,
bool *have_pending_txes)
{
dlist_mutable_iter iter;
XLogRecPtr local_flush = GetFlushRecPtr(NULL);
*write = InvalidXLogRecPtr;
*flush = InvalidXLogRecPtr;
dlist_foreach_modify(iter, &lsn_mapping)
{
FlushPosition *pos =
dlist_container(FlushPosition, node, iter.cur);
*write = pos->remote_end;
if (pos->local_end <= local_flush)
{
*flush = pos->remote_end;
dlist_delete(iter.cur);
pfree(pos);
}
else
{
/*
* Don't want to uselessly iterate over the rest of the list which
* could potentially be long. Instead get the last element and
* grab the write position from there.
*/
pos = dlist_tail_element(FlushPosition, node,
&lsn_mapping);
*write = pos->remote_end;
*have_pending_txes = true;
return;
}
}
*have_pending_txes = !dlist_is_empty(&lsn_mapping);
}
/*
* Store current remote/local lsn pair in the tracking list.
*/
static void
store_flush_position(XLogRecPtr remote_lsn)
{
FlushPosition *flushpos;
/* Need to do this in permanent context */
MemoryContextSwitchTo(ApplyContext);
/* Track commit lsn */
flushpos = (FlushPosition *) palloc(sizeof(FlushPosition));
flushpos->local_end = XactLastCommitEnd;
flushpos->remote_end = remote_lsn;
dlist_push_tail(&lsn_mapping, &flushpos->node);
MemoryContextSwitchTo(ApplyMessageContext);
}
/* Update statistics of the worker. */
static void
UpdateWorkerStats(XLogRecPtr last_lsn, TimestampTz send_time, bool reply)
{
MyLogicalRepWorker->last_lsn = last_lsn;
MyLogicalRepWorker->last_send_time = send_time;
MyLogicalRepWorker->last_recv_time = GetCurrentTimestamp();
if (reply)
{
MyLogicalRepWorker->reply_lsn = last_lsn;
MyLogicalRepWorker->reply_time = send_time;
}
}
/*
* Apply main loop.
*/
static void
LogicalRepApplyLoop(XLogRecPtr last_received)
{
TimestampTz last_recv_timestamp = GetCurrentTimestamp();
bool ping_sent = false;
TimeLineID tli;
ErrorContextCallback errcallback;
/*
* Init the ApplyMessageContext which we clean up after each replication
* protocol message.
*/
ApplyMessageContext = AllocSetContextCreate(ApplyContext,
"ApplyMessageContext",
ALLOCSET_DEFAULT_SIZES);
/*
* This memory context is used for per-stream data when the streaming mode
* is enabled. This context is reset on each stream stop.
*/
LogicalStreamingContext = AllocSetContextCreate(ApplyContext,
"LogicalStreamingContext",
ALLOCSET_DEFAULT_SIZES);
/* mark as idle, before starting to loop */
pgstat_report_activity(STATE_IDLE, NULL);
/*
* Push apply error context callback. Fields will be filled while applying
* a change.
*/
errcallback.callback = apply_error_callback;
errcallback.previous = error_context_stack;
error_context_stack = &errcallback;
/* This outer loop iterates once per wait. */
for (;;)
{
pgsocket fd = PGINVALID_SOCKET;
int rc;
int len;
char *buf = NULL;
bool endofstream = false;
long wait_time;
CHECK_FOR_INTERRUPTS();
MemoryContextSwitchTo(ApplyMessageContext);
len = walrcv_receive(LogRepWorkerWalRcvConn, &buf, &fd);
if (len != 0)
{
/* Loop to process all available data (without blocking). */
for (;;)
{
CHECK_FOR_INTERRUPTS();
if (len == 0)
{
break;
}
else if (len < 0)
{
ereport(LOG,
(errmsg("data stream from publisher has ended")));
endofstream = true;
break;
}
else
{
int c;
StringInfoData s;
/* Reset timeout. */
last_recv_timestamp = GetCurrentTimestamp();
ping_sent = false;
/* Ensure we are reading the data into our memory context. */
MemoryContextSwitchTo(ApplyMessageContext);
s.data = buf;
s.len = len;
s.cursor = 0;
s.maxlen = -1;
c = pq_getmsgbyte(&s);
if (c == 'w')
{
XLogRecPtr start_lsn;
XLogRecPtr end_lsn;
TimestampTz send_time;
start_lsn = pq_getmsgint64(&s);
end_lsn = pq_getmsgint64(&s);
send_time = pq_getmsgint64(&s);
if (last_received < start_lsn)
last_received = start_lsn;
if (last_received < end_lsn)
last_received = end_lsn;
UpdateWorkerStats(last_received, send_time, false);
apply_dispatch(&s);
}
else if (c == 'k')
{
XLogRecPtr end_lsn;
TimestampTz timestamp;
bool reply_requested;
end_lsn = pq_getmsgint64(&s);
timestamp = pq_getmsgint64(&s);
reply_requested = pq_getmsgbyte(&s);
if (last_received < end_lsn)
last_received = end_lsn;
send_feedback(last_received, reply_requested, false);
UpdateWorkerStats(last_received, timestamp, true);
}
/* other message types are purposefully ignored */
MemoryContextReset(ApplyMessageContext);
}
len = walrcv_receive(LogRepWorkerWalRcvConn, &buf, &fd);
}
}
/* confirm all writes so far */
send_feedback(last_received, false, false);
if (!in_remote_transaction && !in_streamed_transaction)
{
/*
* If we didn't get any transactions for a while there might be
* unconsumed invalidation messages in the queue, consume them
* now.
*/
AcceptInvalidationMessages();
maybe_reread_subscription();
/* Process any table synchronization changes. */
process_syncing_tables(last_received);
}
/* Cleanup the memory. */
MemoryContextResetAndDeleteChildren(ApplyMessageContext);
MemoryContextSwitchTo(TopMemoryContext);
/* Check if we need to exit the streaming loop. */
if (endofstream)
break;
/*
* Wait for more data or latch. If we have unflushed transactions,
* wake up after WalWriterDelay to see if they've been flushed yet (in
* which case we should send a feedback message). Otherwise, there's
* no particular urgency about waking up unless we get data or a
* signal.
*/
if (!dlist_is_empty(&lsn_mapping))
wait_time = WalWriterDelay;
else
wait_time = NAPTIME_PER_CYCLE;
rc = WaitLatchOrSocket(MyLatch,
WL_SOCKET_READABLE | WL_LATCH_SET |
WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
fd, wait_time,
WAIT_EVENT_LOGICAL_APPLY_MAIN);
if (rc & WL_LATCH_SET)
{
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
}
if (ConfigReloadPending)
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
}
if (rc & WL_TIMEOUT)
{
/*
* We didn't receive anything new. If we haven't heard anything
* from the server for more than wal_receiver_timeout / 2, ping
* the server. Also, if it's been longer than
* wal_receiver_status_interval since the last update we sent,
* send a status update to the primary anyway, to report any
* progress in applying WAL.
*/
bool requestReply = false;
/*
* Check if time since last receive from primary has reached the
* configured limit.
*/
if (wal_receiver_timeout > 0)
{
TimestampTz now = GetCurrentTimestamp();
TimestampTz timeout;
timeout =
TimestampTzPlusMilliseconds(last_recv_timestamp,
wal_receiver_timeout);
if (now >= timeout)
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_FAILURE),
errmsg("terminating logical replication worker due to timeout")));
/* Check to see if it's time for a ping. */
if (!ping_sent)
{
timeout = TimestampTzPlusMilliseconds(last_recv_timestamp,
(wal_receiver_timeout / 2));
if (now >= timeout)
{
requestReply = true;
ping_sent = true;
}
}
}
send_feedback(last_received, requestReply, requestReply);
}
}
/* Pop the error context stack */
error_context_stack = errcallback.previous;
/* All done */
walrcv_endstreaming(LogRepWorkerWalRcvConn, &tli);
}
/*
* Send a Standby Status Update message to server.
*
* 'recvpos' is the latest LSN we've received data to, force is set if we need
* to send a response to avoid timeouts.
*/
static void
send_feedback(XLogRecPtr recvpos, bool force, bool requestReply)
{
static StringInfo reply_message = NULL;
static TimestampTz send_time = 0;
static XLogRecPtr last_recvpos = InvalidXLogRecPtr;
static XLogRecPtr last_writepos = InvalidXLogRecPtr;
static XLogRecPtr last_flushpos = InvalidXLogRecPtr;
XLogRecPtr writepos;
XLogRecPtr flushpos;
TimestampTz now;
bool have_pending_txes;
/*
* If the user doesn't want status to be reported to the publisher, be
* sure to exit before doing anything at all.
*/
if (!force && wal_receiver_status_interval <= 0)
return;
/* It's legal to not pass a recvpos */
if (recvpos < last_recvpos)
recvpos = last_recvpos;
get_flush_position(&writepos, &flushpos, &have_pending_txes);
/*
* No outstanding transactions to flush, we can report the latest received
* position. This is important for synchronous replication.
*/
if (!have_pending_txes)
flushpos = writepos = recvpos;
if (writepos < last_writepos)
writepos = last_writepos;
if (flushpos < last_flushpos)
flushpos = last_flushpos;
now = GetCurrentTimestamp();
/* if we've already reported everything we're good */
if (!force &&
writepos == last_writepos &&
flushpos == last_flushpos &&
!TimestampDifferenceExceeds(send_time, now,
wal_receiver_status_interval * 1000))
return;
send_time = now;
if (!reply_message)
{
MemoryContext oldctx = MemoryContextSwitchTo(ApplyContext);
reply_message = makeStringInfo();
MemoryContextSwitchTo(oldctx);
}
else
resetStringInfo(reply_message);
pq_sendbyte(reply_message, 'r');
pq_sendint64(reply_message, recvpos); /* write */
pq_sendint64(reply_message, flushpos); /* flush */
pq_sendint64(reply_message, writepos); /* apply */
pq_sendint64(reply_message, now); /* sendTime */
pq_sendbyte(reply_message, requestReply); /* replyRequested */
elog(DEBUG2, "sending feedback (force %d) to recv %X/%X, write %X/%X, flush %X/%X",
force,
LSN_FORMAT_ARGS(recvpos),
LSN_FORMAT_ARGS(writepos),
LSN_FORMAT_ARGS(flushpos));
walrcv_send(LogRepWorkerWalRcvConn,
reply_message->data, reply_message->len);
if (recvpos > last_recvpos)
last_recvpos = recvpos;
if (writepos > last_writepos)
last_writepos = writepos;
if (flushpos > last_flushpos)
last_flushpos = flushpos;
}
/*
* Reread subscription info if needed. Most changes will be exit.
*/
static void
maybe_reread_subscription(void)
{
MemoryContext oldctx;
Subscription *newsub;
bool started_tx = false;
/* When cache state is valid there is nothing to do here. */
if (MySubscriptionValid)
return;
/* This function might be called inside or outside of transaction. */
if (!IsTransactionState())
{
StartTransactionCommand();
started_tx = true;
}
/* Ensure allocations in permanent context. */
oldctx = MemoryContextSwitchTo(ApplyContext);
newsub = GetSubscription(MyLogicalRepWorker->subid, true);
/*
* Exit if the subscription was removed. This normally should not happen
* as the worker gets killed during DROP SUBSCRIPTION.
*/
if (!newsub)
{
ereport(LOG,
(errmsg("logical replication apply worker for subscription \"%s\" will "
"stop because the subscription was removed",
MySubscription->name)));
proc_exit(0);
}
/* Exit if the subscription was disabled. */
if (!newsub->enabled)
{
ereport(LOG,
(errmsg("logical replication apply worker for subscription \"%s\" will "
"stop because the subscription was disabled",
MySubscription->name)));
proc_exit(0);
}
/* !slotname should never happen when enabled is true. */
Assert(newsub->slotname);
/* two-phase should not be altered */
Assert(newsub->twophasestate == MySubscription->twophasestate);
/*
* Exit if any parameter that affects the remote connection was changed.
* The launcher will start a new worker.
*/
if (strcmp(newsub->conninfo, MySubscription->conninfo) != 0 ||
strcmp(newsub->name, MySubscription->name) != 0 ||
strcmp(newsub->slotname, MySubscription->slotname) != 0 ||
newsub->binary != MySubscription->binary ||
newsub->stream != MySubscription->stream ||
newsub->owner != MySubscription->owner ||
!equal(newsub->publications, MySubscription->publications))
{
ereport(LOG,
(errmsg("logical replication apply worker for subscription \"%s\" will restart because of a parameter change",
MySubscription->name)));
proc_exit(0);
}
/* Check for other changes that should never happen too. */
if (newsub->dbid != MySubscription->dbid)
{
elog(ERROR, "subscription %u changed unexpectedly",
MyLogicalRepWorker->subid);
}
/* Clean old subscription info and switch to new one. */
FreeSubscription(MySubscription);
MySubscription = newsub;
MemoryContextSwitchTo(oldctx);
/* Change synchronous commit according to the user's wishes */
SetConfigOption("synchronous_commit", MySubscription->synccommit,
PGC_BACKEND, PGC_S_OVERRIDE);
if (started_tx)
CommitTransactionCommand();
MySubscriptionValid = true;
}
/*
* Callback from subscription syscache invalidation.
*/
static void
subscription_change_cb(Datum arg, int cacheid, uint32 hashvalue)
{
MySubscriptionValid = false;
}
/*
* subxact_info_write
* Store information about subxacts for a toplevel transaction.
*
* For each subxact we store offset of it's first change in the main file.
* The file is always over-written as a whole.
*
* XXX We should only store subxacts that were not aborted yet.
*/
static void
subxact_info_write(Oid subid, TransactionId xid)
{
char path[MAXPGPATH];
Size len;
BufFile *fd;
Assert(TransactionIdIsValid(xid));
/* construct the subxact filename */
subxact_filename(path, subid, xid);
/* Delete the subxacts file, if exists. */
if (subxact_data.nsubxacts == 0)
{
cleanup_subxact_info();
BufFileDeleteFileSet(MyLogicalRepWorker->stream_fileset, path, true);
return;
}
/*
* Create the subxact file if it not already created, otherwise open the
* existing file.
*/
fd = BufFileOpenFileSet(MyLogicalRepWorker->stream_fileset, path, O_RDWR,
true);
if (fd == NULL)
fd = BufFileCreateFileSet(MyLogicalRepWorker->stream_fileset, path);
len = sizeof(SubXactInfo) * subxact_data.nsubxacts;
/* Write the subxact count and subxact info */
BufFileWrite(fd, &subxact_data.nsubxacts, sizeof(subxact_data.nsubxacts));
BufFileWrite(fd, subxact_data.subxacts, len);
BufFileClose(fd);
/* free the memory allocated for subxact info */
cleanup_subxact_info();
}
/*
* subxact_info_read
* Restore information about subxacts of a streamed transaction.
*
* Read information about subxacts into the structure subxact_data that can be
* used later.
*/
static void
subxact_info_read(Oid subid, TransactionId xid)
{
char path[MAXPGPATH];
Size len;
BufFile *fd;
MemoryContext oldctx;
Assert(!subxact_data.subxacts);
Assert(subxact_data.nsubxacts == 0);
Assert(subxact_data.nsubxacts_max == 0);
/*
* If the subxact file doesn't exist that means we don't have any subxact
* info.
*/
subxact_filename(path, subid, xid);
fd = BufFileOpenFileSet(MyLogicalRepWorker->stream_fileset, path, O_RDONLY,
true);
if (fd == NULL)
return;
/* read number of subxact items */
if (BufFileRead(fd, &subxact_data.nsubxacts,
sizeof(subxact_data.nsubxacts)) !=
sizeof(subxact_data.nsubxacts))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from streaming transaction's subxact file \"%s\": %m",
path)));
len = sizeof(SubXactInfo) * subxact_data.nsubxacts;
/* we keep the maximum as a power of 2 */
subxact_data.nsubxacts_max = 1 << my_log2(subxact_data.nsubxacts);
/*
* Allocate subxact information in the logical streaming context. We need
* this information during the complete stream so that we can add the sub
* transaction info to this. On stream stop we will flush this information
* to the subxact file and reset the logical streaming context.
*/
oldctx = MemoryContextSwitchTo(LogicalStreamingContext);
subxact_data.subxacts = palloc(subxact_data.nsubxacts_max *
sizeof(SubXactInfo));
MemoryContextSwitchTo(oldctx);
if ((len > 0) && ((BufFileRead(fd, subxact_data.subxacts, len)) != len))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from streaming transaction's subxact file \"%s\": %m",
path)));
BufFileClose(fd);
}
/*
* subxact_info_add
* Add information about a subxact (offset in the main file).
*/
static void
subxact_info_add(TransactionId xid)
{
SubXactInfo *subxacts = subxact_data.subxacts;
int64 i;
/* We must have a valid top level stream xid and a stream fd. */
Assert(TransactionIdIsValid(stream_xid));
Assert(stream_fd != NULL);
/*
* If the XID matches the toplevel transaction, we don't want to add it.
*/
if (stream_xid == xid)
return;
/*
* In most cases we're checking the same subxact as we've already seen in
* the last call, so make sure to ignore it (this change comes later).
*/
if (subxact_data.subxact_last == xid)
return;
/* OK, remember we're processing this XID. */
subxact_data.subxact_last = xid;
/*
* Check if the transaction is already present in the array of subxact. We
* intentionally scan the array from the tail, because we're likely adding
* a change for the most recent subtransactions.
*
* XXX Can we rely on the subxact XIDs arriving in sorted order? That
* would allow us to use binary search here.
*/
for (i = subxact_data.nsubxacts; i > 0; i--)
{
/* found, so we're done */
if (subxacts[i - 1].xid == xid)
return;
}
/* This is a new subxact, so we need to add it to the array. */
if (subxact_data.nsubxacts == 0)
{
MemoryContext oldctx;
subxact_data.nsubxacts_max = 128;
/*
* Allocate this memory for subxacts in per-stream context, see
* subxact_info_read.
*/
oldctx = MemoryContextSwitchTo(LogicalStreamingContext);
subxacts = palloc(subxact_data.nsubxacts_max * sizeof(SubXactInfo));
MemoryContextSwitchTo(oldctx);
}
else if (subxact_data.nsubxacts == subxact_data.nsubxacts_max)
{
subxact_data.nsubxacts_max *= 2;
subxacts = repalloc(subxacts,
subxact_data.nsubxacts_max * sizeof(SubXactInfo));
}
subxacts[subxact_data.nsubxacts].xid = xid;
/*
* Get the current offset of the stream file and store it as offset of
* this subxact.
*/
BufFileTell(stream_fd,
&subxacts[subxact_data.nsubxacts].fileno,
&subxacts[subxact_data.nsubxacts].offset);
subxact_data.nsubxacts++;
subxact_data.subxacts = subxacts;
}
/* format filename for file containing the info about subxacts */
static inline void
subxact_filename(char *path, Oid subid, TransactionId xid)
{
snprintf(path, MAXPGPATH, "%u-%u.subxacts", subid, xid);
}
/* format filename for file containing serialized changes */
static inline void
changes_filename(char *path, Oid subid, TransactionId xid)
{
snprintf(path, MAXPGPATH, "%u-%u.changes", subid, xid);
}
/*
* stream_cleanup_files
* Cleanup files for a subscription / toplevel transaction.
*
* Remove files with serialized changes and subxact info for a particular
* toplevel transaction. Each subscription has a separate set of files
* for any toplevel transaction.
*/
static void
stream_cleanup_files(Oid subid, TransactionId xid)
{
char path[MAXPGPATH];
/* Delete the changes file. */
changes_filename(path, subid, xid);
BufFileDeleteFileSet(MyLogicalRepWorker->stream_fileset, path, false);
/* Delete the subxact file, if it exists. */
subxact_filename(path, subid, xid);
BufFileDeleteFileSet(MyLogicalRepWorker->stream_fileset, path, true);
}
/*
* stream_open_file
* Open a file that we'll use to serialize changes for a toplevel
* transaction.
*
* Open a file for streamed changes from a toplevel transaction identified
* by stream_xid (global variable). If it's the first chunk of streamed
* changes for this transaction, create the buffile, otherwise open the
* previously created file.
*
* This can only be called at the beginning of a "streaming" block, i.e.
* between stream_start/stream_stop messages from the upstream.
*/
static void
stream_open_file(Oid subid, TransactionId xid, bool first_segment)
{
char path[MAXPGPATH];
MemoryContext oldcxt;
Assert(in_streamed_transaction);
Assert(OidIsValid(subid));
Assert(TransactionIdIsValid(xid));
Assert(stream_fd == NULL);
changes_filename(path, subid, xid);
elog(DEBUG1, "opening file \"%s\" for streamed changes", path);
/*
* Create/open the buffiles under the logical streaming context so that we
* have those files until stream stop.
*/
oldcxt = MemoryContextSwitchTo(LogicalStreamingContext);
/*
* If this is the first streamed segment, create the changes file.
* Otherwise, just open the file for writing, in append mode.
*/
if (first_segment)
stream_fd = BufFileCreateFileSet(MyLogicalRepWorker->stream_fileset,
path);
else
{
/*
* Open the file and seek to the end of the file because we always
* append the changes file.
*/
stream_fd = BufFileOpenFileSet(MyLogicalRepWorker->stream_fileset,
path, O_RDWR, false);
BufFileSeek(stream_fd, 0, 0, SEEK_END);
}
MemoryContextSwitchTo(oldcxt);
}
/*
* stream_close_file
* Close the currently open file with streamed changes.
*
* This can only be called at the end of a streaming block, i.e. at stream_stop
* message from the upstream.
*/
static void
stream_close_file(void)
{
Assert(in_streamed_transaction);
Assert(TransactionIdIsValid(stream_xid));
Assert(stream_fd != NULL);
BufFileClose(stream_fd);
stream_xid = InvalidTransactionId;
stream_fd = NULL;
}
/*
* stream_write_change
* Serialize a change to a file for the current toplevel transaction.
*
* The change is serialized in a simple format, with length (not including
* the length), action code (identifying the message type) and message
* contents (without the subxact TransactionId value).
*/
static void
stream_write_change(char action, StringInfo s)
{
int len;
Assert(in_streamed_transaction);
Assert(TransactionIdIsValid(stream_xid));
Assert(stream_fd != NULL);
/* total on-disk size, including the action type character */
len = (s->len - s->cursor) + sizeof(char);
/* first write the size */
BufFileWrite(stream_fd, &len, sizeof(len));
/* then the action */
BufFileWrite(stream_fd, &action, sizeof(action));
/* and finally the remaining part of the buffer (after the XID) */
len = (s->len - s->cursor);
BufFileWrite(stream_fd, &s->data[s->cursor], len);
}
/*
* Cleanup the memory for subxacts and reset the related variables.
*/
static inline void
cleanup_subxact_info()
{
if (subxact_data.subxacts)
pfree(subxact_data.subxacts);
subxact_data.subxacts = NULL;
subxact_data.subxact_last = InvalidTransactionId;
subxact_data.nsubxacts = 0;
subxact_data.nsubxacts_max = 0;
}
/*
* Form the prepared transaction GID for two_phase transactions.
*
* Return the GID in the supplied buffer.
*/
static void
TwoPhaseTransactionGid(Oid subid, TransactionId xid, char *gid, int szgid)
{
Assert(subid != InvalidRepOriginId);
if (!TransactionIdIsValid(xid))
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("invalid two-phase transaction ID")));
snprintf(gid, szgid, "pg_gid_%u_%u", subid, xid);
}
/* Logical Replication Apply worker entry point */
void
ApplyWorkerMain(Datum main_arg)
{
int worker_slot = DatumGetInt32(main_arg);
MemoryContext oldctx;
char originname[NAMEDATALEN];
XLogRecPtr origin_startpos;
char *myslotname;
WalRcvStreamOptions options;
int server_version;
/* Attach to slot */
logicalrep_worker_attach(worker_slot);
/* Setup signal handling */
pqsignal(SIGHUP, SignalHandlerForConfigReload);
pqsignal(SIGTERM, die);
BackgroundWorkerUnblockSignals();
/*
* We don't currently need any ResourceOwner in a walreceiver process, but
* if we did, we could call CreateAuxProcessResourceOwner here.
*/
/* Initialise stats to a sanish value */
MyLogicalRepWorker->last_send_time = MyLogicalRepWorker->last_recv_time =
MyLogicalRepWorker->reply_time = GetCurrentTimestamp();
/* Load the libpq-specific functions */
load_file("libpqwalreceiver", false);
/* Run as replica session replication role. */
SetConfigOption("session_replication_role", "replica",
PGC_SUSET, PGC_S_OVERRIDE);
/* Connect to our database. */
BackgroundWorkerInitializeConnectionByOid(MyLogicalRepWorker->dbid,
MyLogicalRepWorker->userid,
0);
/*
* Set always-secure search path, so malicious users can't redirect user
* code (e.g. pg_index.indexprs).
*/
SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
/* Load the subscription into persistent memory context. */
ApplyContext = AllocSetContextCreate(TopMemoryContext,
"ApplyContext",
ALLOCSET_DEFAULT_SIZES);
StartTransactionCommand();
oldctx = MemoryContextSwitchTo(ApplyContext);
MySubscription = GetSubscription(MyLogicalRepWorker->subid, true);
if (!MySubscription)
{
ereport(LOG,
(errmsg("logical replication apply worker for subscription %u will not "
"start because the subscription was removed during startup",
MyLogicalRepWorker->subid)));
proc_exit(0);
}
MySubscriptionValid = true;
MemoryContextSwitchTo(oldctx);
if (!MySubscription->enabled)
{
ereport(LOG,
(errmsg("logical replication apply worker for subscription \"%s\" will not "
"start because the subscription was disabled during startup",
MySubscription->name)));
proc_exit(0);
}
/* Setup synchronous commit according to the user's wishes */
SetConfigOption("synchronous_commit", MySubscription->synccommit,
PGC_BACKEND, PGC_S_OVERRIDE);
/* Keep us informed about subscription changes. */
CacheRegisterSyscacheCallback(SUBSCRIPTIONOID,
subscription_change_cb,
(Datum) 0);
if (am_tablesync_worker())
ereport(LOG,
(errmsg("logical replication table synchronization worker for subscription \"%s\", table \"%s\" has started",
MySubscription->name, get_rel_name(MyLogicalRepWorker->relid))));
else
ereport(LOG,
(errmsg("logical replication apply worker for subscription \"%s\" has started",
MySubscription->name)));
CommitTransactionCommand();
/* Connect to the origin and start the replication. */
elog(DEBUG1, "connecting to publisher using connection string \"%s\"",
MySubscription->conninfo);
if (am_tablesync_worker())
{
char *syncslotname;
PG_TRY();
{
/* This is table synchronization worker, call initial sync. */
syncslotname = LogicalRepSyncTableStart(&origin_startpos);
}
PG_CATCH();
{
/*
* Abort the current transaction so that we send the stats message
* in an idle state.
*/
AbortOutOfAnyTransaction();
/* Report the worker failed during table synchronization */
pgstat_report_subscription_error(MySubscription->oid, false);
PG_RE_THROW();
}
PG_END_TRY();
/* allocate slot name in long-lived context */
myslotname = MemoryContextStrdup(ApplyContext, syncslotname);
pfree(syncslotname);
}
else
{
/* This is main apply worker */
RepOriginId originid;
TimeLineID startpointTLI;
char *err;
myslotname = MySubscription->slotname;
/*
* This shouldn't happen if the subscription is enabled, but guard
* against DDL bugs or manual catalog changes. (libpqwalreceiver will
* crash if slot is NULL.)
*/
if (!myslotname)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("subscription has no replication slot set")));
/* Setup replication origin tracking. */
StartTransactionCommand();
snprintf(originname, sizeof(originname), "pg_%u", MySubscription->oid);
originid = replorigin_by_name(originname, true);
if (!OidIsValid(originid))
originid = replorigin_create(originname);
replorigin_session_setup(originid);
replorigin_session_origin = originid;
origin_startpos = replorigin_session_get_progress(false);
CommitTransactionCommand();
LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
MySubscription->name, &err);
if (LogRepWorkerWalRcvConn == NULL)
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_FAILURE),
errmsg("could not connect to the publisher: %s", err)));
/*
* We don't really use the output identify_system for anything but it
* does some initializations on the upstream so let's still call it.
*/
(void) walrcv_identify_system(LogRepWorkerWalRcvConn, &startpointTLI);
}
/*
* Setup callback for syscache so that we know when something changes in
* the subscription relation state.
*/
CacheRegisterSyscacheCallback(SUBSCRIPTIONRELMAP,
invalidate_syncing_table_states,
(Datum) 0);
/* Build logical replication streaming options. */
options.logical = true;
options.startpoint = origin_startpos;
options.slotname = myslotname;
server_version = walrcv_server_version(LogRepWorkerWalRcvConn);
options.proto.logical.proto_version =
server_version >= 150000 ? LOGICALREP_PROTO_TWOPHASE_VERSION_NUM :
server_version >= 140000 ? LOGICALREP_PROTO_STREAM_VERSION_NUM :
LOGICALREP_PROTO_VERSION_NUM;
options.proto.logical.publication_names = MySubscription->publications;
options.proto.logical.binary = MySubscription->binary;
options.proto.logical.streaming = MySubscription->stream;
options.proto.logical.twophase = false;
if (!am_tablesync_worker())
{
/*
* Even when the two_phase mode is requested by the user, it remains
* as the tri-state PENDING until all tablesyncs have reached READY
* state. Only then, can it become ENABLED.
*
* Note: If the subscription has no tables then leave the state as
* PENDING, which allows ALTER SUBSCRIPTION ... REFRESH PUBLICATION to
* work.
*/
if (MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING &&
AllTablesyncsReady())
{
/* Start streaming with two_phase enabled */
options.proto.logical.twophase = true;
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
StartTransactionCommand();
UpdateTwoPhaseState(MySubscription->oid, LOGICALREP_TWOPHASE_STATE_ENABLED);
MySubscription->twophasestate = LOGICALREP_TWOPHASE_STATE_ENABLED;
CommitTransactionCommand();
}
else
{
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
}
ereport(DEBUG1,
(errmsg("logical replication apply worker for subscription \"%s\" two_phase is %s",
MySubscription->name,
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_DISABLED ? "DISABLED" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING ? "PENDING" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED ? "ENABLED" :
"?")));
}
else
{
/* Start normal logical streaming replication. */
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
}
/* Run the main loop. */
PG_TRY();
{
LogicalRepApplyLoop(origin_startpos);
}
PG_CATCH();
{
/*
* Abort the current transaction so that we send the stats message in
* an idle state.
*/
AbortOutOfAnyTransaction();
/* Report the worker failed while applying changes */
pgstat_report_subscription_error(MySubscription->oid, !am_tablesync_worker());
PG_RE_THROW();
}
PG_END_TRY();
proc_exit(0);
}
/*
* Is current process a logical replication worker?
*/
bool
IsLogicalWorker(void)
{
return MyLogicalRepWorker != NULL;
}
/* Error callback to give more context info about the change being applied */
static void
apply_error_callback(void *arg)
{
StringInfoData buf;
ApplyErrorCallbackArg *errarg = &apply_error_callback_arg;
if (apply_error_callback_arg.command == 0)
return;
initStringInfo(&buf);
appendStringInfo(&buf, _("processing remote data during \"%s\""),
logicalrep_message_type(errarg->command));
/* append relation information */
if (errarg->rel)
{
appendStringInfo(&buf, _(" for replication target relation \"%s.%s\""),
errarg->rel->remoterel.nspname,
errarg->rel->remoterel.relname);
if (errarg->remote_attnum >= 0)
appendStringInfo(&buf, _(" column \"%s\""),
errarg->rel->remoterel.attnames[errarg->remote_attnum]);
}
/* append transaction information */
if (TransactionIdIsNormal(errarg->remote_xid))
{
appendStringInfo(&buf, _(" in transaction %u"), errarg->remote_xid);
if (errarg->ts != 0)
appendStringInfo(&buf, _(" at %s"),
timestamptz_to_str(errarg->ts));
}
errcontext("%s", buf.data);
pfree(buf.data);
}
/* Set transaction information of apply error callback */
static inline void
set_apply_error_context_xact(TransactionId xid, TimestampTz ts)
{
apply_error_callback_arg.remote_xid = xid;
apply_error_callback_arg.ts = ts;
}
/* Reset all information of apply error callback */
static inline void
reset_apply_error_context_info(void)
{
apply_error_callback_arg.command = 0;
apply_error_callback_arg.rel = NULL;
apply_error_callback_arg.remote_attnum = -1;
set_apply_error_context_xact(InvalidTransactionId, 0);
}
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