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postgres/src/backend/commands/command.c
Tom Lane 01b73d3f27 Fix foreign keys on system columns.
2001-10-23 17:39:03 +00:00

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/*-------------------------------------------------------------------------
*
* command.c
* random postgres portal and utility support code
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.145 2001/10/23 17:39:02 tgl Exp $
*
* NOTES
* The PerformAddAttribute() code, like most of the relation
* manipulating code in the commands/ directory, should go
* someplace closer to the lib/catalog code.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/tuptoaster.h"
#include "catalog/catalog.h"
#include "catalog/catname.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_index.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_type.h"
#include "commands/command.h"
#include "commands/trigger.h"
#include "commands/defrem.h" /* For add constraint unique, primary */
#include "executor/execdefs.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/prep.h"
#include "parser/parse.h"
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/analyze.h" /* For add constraint unique, primary */
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
#include "utils/relcache.h"
#include "utils/temprel.h"
static void drop_default(Oid relid, int16 attnum);
static bool needs_toast_table(Relation rel);
static bool is_relation(char *name);
/* --------------------------------
* PortalCleanup
* --------------------------------
*/
void
PortalCleanup(Portal portal)
{
MemoryContext oldcontext;
/*
* sanity checks
*/
AssertArg(PortalIsValid(portal));
AssertArg(portal->cleanup == PortalCleanup);
/*
* set proper portal-executor context before calling ExecMain.
*/
oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
/*
* tell the executor to shutdown the query
*/
ExecutorEnd(PortalGetQueryDesc(portal), PortalGetState(portal));
/*
* switch back to previous context
*/
MemoryContextSwitchTo(oldcontext);
}
/* --------------------------------
* PerformPortalFetch
* --------------------------------
*/
void
PerformPortalFetch(char *name,
bool forward,
int count,
char *tag,
CommandDest dest)
{
Portal portal;
QueryDesc *queryDesc;
EState *estate;
MemoryContext oldcontext;
bool temp_desc = false;
/*
* sanity checks
*/
if (name == NULL)
{
elog(NOTICE, "PerformPortalFetch: missing portal name");
return;
}
/*
* get the portal from the portal name
*/
portal = GetPortalByName(name);
if (!PortalIsValid(portal))
{
elog(NOTICE, "PerformPortalFetch: portal \"%s\" not found",
name);
return;
}
/*
* switch into the portal context
*/
oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
/*
* If the requested destination is not the same as the query's
* original destination, make a temporary QueryDesc with the proper
* destination. This supports MOVE, for example, which will pass in
* dest = None.
*
* EXCEPTION: if the query's original dest is RemoteInternal (ie, it's
* a binary cursor) and the request is Remote, we do NOT override the
* original dest. This is necessary since a FETCH command will pass
* dest = Remote, not knowing whether the cursor is binary or not.
*/
queryDesc = PortalGetQueryDesc(portal);
estate = PortalGetState(portal);
if (dest != queryDesc->dest &&
!(queryDesc->dest == RemoteInternal && dest == Remote))
{
QueryDesc *qdesc = (QueryDesc *) palloc(sizeof(QueryDesc));
memcpy(qdesc, queryDesc, sizeof(QueryDesc));
qdesc->dest = dest;
queryDesc = qdesc;
temp_desc = true;
}
/*
* tell the destination to prepare to receive some tuples.
*/
BeginCommand(name,
queryDesc->operation,
PortalGetTupleDesc(portal),
false, /* portal fetches don't end up in
* relations */
false, /* this is a portal fetch, not a "retrieve
* portal" */
tag,
queryDesc->dest);
/*
* Determine which direction to go in, and check to see if we're
* already at the end of the available tuples in that direction. If
* so, do nothing. (This check exists because not all plan node types
* are robust about being called again if they've already returned
* NULL once.) If it's OK to do the fetch, call the executor. Then,
* update the atStart/atEnd state depending on the number of tuples
* that were retrieved.
*/
if (forward)
{
if (!portal->atEnd)
{
ExecutorRun(queryDesc, estate, EXEC_FOR, (long) count);
/*
* I use CMD_UPDATE, because no CMD_MOVE or the like
* exists, and I would like to provide the same
* kind of info as CMD_UPDATE
*/
UpdateCommandInfo(CMD_UPDATE, 0, estate->es_processed);
if (estate->es_processed > 0)
portal->atStart = false; /* OK to back up now */
if (count <= 0 || (int) estate->es_processed < count)
portal->atEnd = true; /* we retrieved 'em all */
}
}
else
{
if (!portal->atStart)
{
ExecutorRun(queryDesc, estate, EXEC_BACK, (long) count);
/*
* I use CMD_UPDATE, because no CMD_MOVE or the like
* exists, and I would like to provide the same
* kind of info as CMD_UPDATE
*/
UpdateCommandInfo(CMD_UPDATE, 0, estate->es_processed);
if (estate->es_processed > 0)
portal->atEnd = false; /* OK to go forward now */
if (count <= 0 || (int) estate->es_processed < count)
portal->atStart = true; /* we retrieved 'em all */
}
}
/*
* Clean up and switch back to old context.
*/
if (temp_desc)
pfree(queryDesc);
MemoryContextSwitchTo(oldcontext);
/*
* Note: the "end-of-command" tag is returned by higher-level utility
* code
*/
}
/* --------------------------------
* PerformPortalClose
* --------------------------------
*/
void
PerformPortalClose(char *name, CommandDest dest)
{
Portal portal;
/*
* sanity checks
*/
if (name == NULL)
{
elog(NOTICE, "PerformPortalClose: missing portal name");
return;
}
/*
* get the portal from the portal name
*/
portal = GetPortalByName(name);
if (!PortalIsValid(portal))
{
elog(NOTICE, "PerformPortalClose: portal \"%s\" not found",
name);
return;
}
/*
* Note: PortalCleanup is called as a side-effect
*/
PortalDrop(portal);
}
/* ----------------
* AlterTableAddColumn
* (formerly known as PerformAddAttribute)
*
* adds an additional attribute to a relation
*
* Adds attribute field(s) to a relation. Each new attribute
* is given attnums in sequential order and is added to the
* ATTRIBUTE relation. If the AMI fails, defunct tuples will
* remain in the ATTRIBUTE relation for later vacuuming.
* Later, there may be some reserved attribute names???
*
* (If needed, can instead use elog to handle exceptions.)
*
* Note:
* Initial idea of ordering the tuple attributes so that all
* the variable length domains occured last was scratched. Doing
* so would not speed access too much (in general) and would create
* many complications in formtuple, heap_getattr, and addattribute.
*
* scan attribute catalog for name conflict (within rel)
* scan type catalog for absence of data type (if not arg)
* create attnum magically???
* create attribute tuple
* insert attribute in attribute catalog
* modify reldesc
* create new relation tuple
* insert new relation in relation catalog
* delete original relation from relation catalog
* ----------------
*/
void
AlterTableAddColumn(const char *relationName,
bool inherits,
ColumnDef *colDef)
{
Relation rel,
attrdesc;
Oid myrelid;
HeapTuple reltup;
HeapTuple newreltup;
HeapTuple attributeTuple;
Form_pg_attribute attribute;
FormData_pg_attribute attributeD;
int i;
int minattnum,
maxatts;
HeapTuple typeTuple;
Form_pg_type tform;
char *typename;
int attndims;
/*
* permissions checking. this would normally be done in utility.c,
* but this particular routine is recursive.
*
* normally, only the owner of a class can change its schema.
*/
if (!allowSystemTableMods && IsSystemRelationName(relationName))
elog(ERROR, "ALTER TABLE: relation \"%s\" is a system catalog",
relationName);
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
/*
* Grab an exclusive lock on the target table, which we will NOT
* release until end of transaction.
*/
rel = heap_openr(relationName, AccessExclusiveLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
relationName);
myrelid = RelationGetRelid(rel);
heap_close(rel, NoLock); /* close rel but keep lock! */
/*
* Recurse to add the column to child classes, if requested.
*
* any permissions or problems with duplicate attributes will cause the
* whole transaction to abort, which is what we want -- all or
* nothing.
*/
if (inherits)
{
List *child,
*children;
/* this routine is actually in the planner */
children = find_all_inheritors(myrelid);
/*
* find_all_inheritors does the recursive search of the
* inheritance hierarchy, so all we have to do is process all
* of the relids in the list that it returns.
*/
foreach(child, children)
{
Oid childrelid = lfirsti(child);
char *childrelname;
if (childrelid == myrelid)
continue;
rel = heap_open(childrelid, AccessExclusiveLock);
childrelname = pstrdup(RelationGetRelationName(rel));
heap_close(rel, AccessExclusiveLock);
AlterTableAddColumn(childrelname, false, colDef);
pfree(childrelname);
}
}
/*
* OK, get on with it...
*
* Implementation restrictions: because we don't touch the table rows,
* the new column values will initially appear to be NULLs. (This
* happens because the heap tuple access routines always check for
* attnum > # of attributes in tuple, and return NULL if so.) Therefore
* we can't support a DEFAULT value in SQL92-compliant fashion, and
* we also can't allow a NOT NULL constraint.
*
* We do allow CHECK constraints, even though these theoretically
* could fail for NULL rows (eg, CHECK (newcol IS NOT NULL)).
*/
if (colDef->raw_default || colDef->cooked_default)
elog(ERROR, "Adding columns with defaults is not implemented."
"\n\tAdd the column, then use ALTER TABLE SET DEFAULT.");
if (colDef->is_not_null)
elog(ERROR, "Adding NOT NULL columns is not implemented."
"\n\tAdd the column, then use ALTER TABLE ADD CONSTRAINT.");
rel = heap_openr(RelationRelationName, RowExclusiveLock);
reltup = SearchSysCache(RELNAME,
PointerGetDatum(relationName),
0, 0, 0);
if (!HeapTupleIsValid(reltup))
elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
relationName);
if (SearchSysCacheExists(ATTNAME,
ObjectIdGetDatum(reltup->t_data->t_oid),
PointerGetDatum(colDef->colname),
0, 0))
elog(ERROR, "ALTER TABLE: column name \"%s\" already exists in table \"%s\"",
colDef->colname, relationName);
minattnum = ((Form_pg_class) GETSTRUCT(reltup))->relnatts;
maxatts = minattnum + 1;
if (maxatts > MaxHeapAttributeNumber)
elog(ERROR, "ALTER TABLE: relations limited to %d columns",
MaxHeapAttributeNumber);
i = minattnum + 1;
attrdesc = heap_openr(AttributeRelationName, RowExclusiveLock);
if (colDef->typename->arrayBounds)
{
attndims = length(colDef->typename->arrayBounds);
typename = makeArrayTypeName(colDef->typename->name);
}
else
{
attndims = 0;
typename = colDef->typename->name;
}
typeTuple = SearchSysCache(TYPENAME,
PointerGetDatum(typename),
0, 0, 0);
if (!HeapTupleIsValid(typeTuple))
elog(ERROR, "ALTER TABLE: type \"%s\" does not exist", typename);
tform = (Form_pg_type) GETSTRUCT(typeTuple);
attributeTuple = heap_addheader(Natts_pg_attribute,
ATTRIBUTE_TUPLE_SIZE,
(void *) &attributeD);
attribute = (Form_pg_attribute) GETSTRUCT(attributeTuple);
attribute->attrelid = reltup->t_data->t_oid;
namestrcpy(&(attribute->attname), colDef->colname);
attribute->atttypid = typeTuple->t_data->t_oid;
attribute->attstattarget = DEFAULT_ATTSTATTARGET;
attribute->attlen = tform->typlen;
attribute->attcacheoff = -1;
attribute->atttypmod = colDef->typename->typmod;
attribute->attnum = i;
attribute->attbyval = tform->typbyval;
attribute->attndims = attndims;
attribute->attisset = (bool) (tform->typtype == 'c');
attribute->attstorage = tform->typstorage;
attribute->attalign = tform->typalign;
attribute->attnotnull = colDef->is_not_null;
attribute->atthasdef = (colDef->raw_default != NULL ||
colDef->cooked_default != NULL);
ReleaseSysCache(typeTuple);
heap_insert(attrdesc, attributeTuple);
/* Update indexes on pg_attribute */
if (RelationGetForm(attrdesc)->relhasindex)
{
Relation idescs[Num_pg_attr_indices];
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_attr_indices, attrdesc, attributeTuple);
CatalogCloseIndices(Num_pg_attr_indices, idescs);
}
heap_close(attrdesc, NoLock);
/*
* Update number of attributes in pg_class tuple
*/
newreltup = heap_copytuple(reltup);
((Form_pg_class) GETSTRUCT(newreltup))->relnatts = maxatts;
simple_heap_update(rel, &newreltup->t_self, newreltup);
/* keep catalog indices current */
if (RelationGetForm(rel)->relhasindex)
{
Relation ridescs[Num_pg_class_indices];
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, ridescs);
CatalogIndexInsert(ridescs, Num_pg_class_indices, rel, newreltup);
CatalogCloseIndices(Num_pg_class_indices, ridescs);
}
heap_freetuple(newreltup);
ReleaseSysCache(reltup);
heap_close(rel, NoLock);
/*
* Make our catalog updates visible for subsequent steps.
*/
CommandCounterIncrement();
/*
* Add any CHECK constraints attached to the new column.
*
* To do this we must re-open the rel so that its new attr list
* gets loaded into the relcache.
*/
if (colDef->constraints != NIL)
{
rel = heap_openr(relationName, AccessExclusiveLock);
AddRelationRawConstraints(rel, NIL, colDef->constraints);
heap_close(rel, NoLock);
}
/*
* Automatically create the secondary relation for TOAST if it
* formerly had no such but now has toastable attributes.
*/
AlterTableCreateToastTable(relationName, true);
}
/*
* ALTER TABLE ALTER COLUMN SET/DROP DEFAULT
*/
void
AlterTableAlterColumnDefault(const char *relationName,
bool inh, const char *colName,
Node *newDefault)
{
Relation rel;
HeapTuple tuple;
int16 attnum;
Oid myrelid;
if (!allowSystemTableMods && IsSystemRelationName(relationName))
elog(ERROR, "ALTER TABLE: relation \"%s\" is a system catalog",
relationName);
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
rel = heap_openr(relationName, AccessExclusiveLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
relationName);
myrelid = RelationGetRelid(rel);
heap_close(rel, NoLock);
/*
* Propagate to children if desired
*/
if (inh)
{
List *child,
*children;
/* this routine is actually in the planner */
children = find_all_inheritors(myrelid);
/*
* find_all_inheritors does the recursive search of the
* inheritance hierarchy, so all we have to do is process all of
* the relids in the list that it returns.
*/
foreach(child, children)
{
Oid childrelid = lfirsti(child);
if (childrelid == myrelid)
continue;
rel = heap_open(childrelid, AccessExclusiveLock);
AlterTableAlterColumnDefault(RelationGetRelationName(rel),
false, colName, newDefault);
heap_close(rel, AccessExclusiveLock);
}
}
/* -= now do the thing on this relation =- */
/* reopen the business */
rel = heap_openr(relationName, AccessExclusiveLock);
/*
* get the number of the attribute
*/
tuple = SearchSysCache(ATTNAME,
ObjectIdGetDatum(myrelid),
PointerGetDatum(colName),
0, 0);
if (!HeapTupleIsValid(tuple))
elog(ERROR, "ALTER TABLE: relation \"%s\" has no column \"%s\"",
relationName, colName);
attnum = ((Form_pg_attribute) GETSTRUCT(tuple))->attnum;
ReleaseSysCache(tuple);
if (newDefault)
{
/* SET DEFAULT */
RawColumnDefault *rawEnt;
/* Get rid of the old one first */
drop_default(myrelid, attnum);
rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
rawEnt->attnum = attnum;
rawEnt->raw_default = newDefault;
/*
* This function is intended for CREATE TABLE, so it processes a
* _list_ of defaults, but we just do one.
*/
AddRelationRawConstraints(rel, makeList1(rawEnt), NIL);
}
else
{
/* DROP DEFAULT */
Relation attr_rel;
ScanKeyData scankeys[3];
HeapScanDesc scan;
attr_rel = heap_openr(AttributeRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&scankeys[0], 0x0,
Anum_pg_attribute_attrelid, F_OIDEQ,
ObjectIdGetDatum(myrelid));
ScanKeyEntryInitialize(&scankeys[1], 0x0,
Anum_pg_attribute_attnum, F_INT2EQ,
Int16GetDatum(attnum));
ScanKeyEntryInitialize(&scankeys[2], 0x0,
Anum_pg_attribute_atthasdef, F_BOOLEQ,
BoolGetDatum(true));
scan = heap_beginscan(attr_rel, false, SnapshotNow, 3, scankeys);
AssertState(scan != NULL);
if (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
{
HeapTuple newtuple;
Relation irelations[Num_pg_attr_indices];
/* update to false */
newtuple = heap_copytuple(tuple);
((Form_pg_attribute) GETSTRUCT(newtuple))->atthasdef = FALSE;
simple_heap_update(attr_rel, &tuple->t_self, newtuple);
/* keep the system catalog indices current */
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, irelations);
CatalogIndexInsert(irelations, Num_pg_attr_indices, attr_rel, newtuple);
CatalogCloseIndices(Num_pg_attr_indices, irelations);
/* get rid of actual default definition */
drop_default(myrelid, attnum);
}
heap_endscan(scan);
heap_close(attr_rel, NoLock);
}
heap_close(rel, NoLock);
}
static void
drop_default(Oid relid, int16 attnum)
{
ScanKeyData scankeys[2];
HeapScanDesc scan;
Relation attrdef_rel;
HeapTuple tuple;
attrdef_rel = heap_openr(AttrDefaultRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&scankeys[0], 0x0,
Anum_pg_attrdef_adrelid, F_OIDEQ,
ObjectIdGetDatum(relid));
ScanKeyEntryInitialize(&scankeys[1], 0x0,
Anum_pg_attrdef_adnum, F_INT2EQ,
Int16GetDatum(attnum));
scan = heap_beginscan(attrdef_rel, false, SnapshotNow, 2, scankeys);
if (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
simple_heap_delete(attrdef_rel, &tuple->t_self);
heap_endscan(scan);
heap_close(attrdef_rel, NoLock);
}
/*
* ALTER TABLE ALTER COLUMN SET STATISTICS
*/
void
AlterTableAlterColumnStatistics(const char *relationName,
bool inh, const char *colName,
Node *statsTarget)
{
Relation rel;
Oid myrelid;
int newtarget;
Relation attrelation;
HeapTuple tuple;
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
rel = heap_openr(relationName, AccessExclusiveLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
relationName);
myrelid = RelationGetRelid(rel);
heap_close(rel, NoLock); /* close rel, but keep lock! */
/*
* Propagate to children if desired
*/
if (inh)
{
List *child,
*children;
/* this routine is actually in the planner */
children = find_all_inheritors(myrelid);
/*
* find_all_inheritors does the recursive search of the
* inheritance hierarchy, so all we have to do is process all of
* the relids in the list that it returns.
*/
foreach(child, children)
{
Oid childrelid = lfirsti(child);
if (childrelid == myrelid)
continue;
rel = heap_open(childrelid, AccessExclusiveLock);
AlterTableAlterColumnStatistics(RelationGetRelationName(rel),
false, colName, statsTarget);
heap_close(rel, AccessExclusiveLock);
}
}
/* -= now do the thing on this relation =- */
Assert(IsA(statsTarget, Integer));
newtarget = intVal(statsTarget);
/* Limit target to sane range (should we raise an error instead?) */
if (newtarget < 0)
newtarget = 0;
else if (newtarget > 1000)
newtarget = 1000;
attrelation = heap_openr(AttributeRelationName, RowExclusiveLock);
tuple = SearchSysCacheCopy(ATTNAME,
ObjectIdGetDatum(myrelid),
PointerGetDatum(colName),
0, 0);
if (!HeapTupleIsValid(tuple))
elog(ERROR, "ALTER TABLE: relation \"%s\" has no column \"%s\"",
relationName, colName);
if (((Form_pg_attribute) GETSTRUCT(tuple))->attnum < 0)
elog(ERROR, "ALTER TABLE: cannot change system attribute \"%s\"",
colName);
((Form_pg_attribute) GETSTRUCT(tuple))->attstattarget = newtarget;
simple_heap_update(attrelation, &tuple->t_self, tuple);
/* keep system catalog indices current */
{
Relation irelations[Num_pg_attr_indices];
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, irelations);
CatalogIndexInsert(irelations, Num_pg_attr_indices, attrelation, tuple);
CatalogCloseIndices(Num_pg_attr_indices, irelations);
}
heap_freetuple(tuple);
heap_close(attrelation, NoLock);
}
#ifdef _DROP_COLUMN_HACK__
/*
* ALTER TABLE DROP COLUMN trial implementation
*
*/
/*
* system table scan(index scan/sequential scan)
*/
typedef struct SysScanDescData
{
Relation heap_rel;
Relation irel;
HeapScanDesc scan;
IndexScanDesc iscan;
HeapTupleData tuple;
Buffer buffer;
} SysScanDescData, *SysScanDesc;
static void *
systable_beginscan(Relation rel, const char *indexRelname, int nkeys, ScanKey entry)
{
bool hasindex = (rel->rd_rel->relhasindex && !IsIgnoringSystemIndexes());
SysScanDesc sysscan;
sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
sysscan->heap_rel = rel;
sysscan->irel = (Relation) NULL;
sysscan->tuple.t_datamcxt = NULL;
sysscan->tuple.t_data = NULL;
sysscan->buffer = InvalidBuffer;
if (hasindex)
{
sysscan->irel = index_openr((char *) indexRelname);
sysscan->iscan = index_beginscan(sysscan->irel, false, nkeys, entry);
}
else
sysscan->scan = heap_beginscan(rel, false, SnapshotNow, nkeys, entry);
return (void *) sysscan;
}
static void
systable_endscan(void *scan)
{
SysScanDesc sysscan = (SysScanDesc) scan;
if (sysscan->irel)
{
if (BufferIsValid(sysscan->buffer))
ReleaseBuffer(sysscan->buffer);
index_endscan(sysscan->iscan);
index_close(sysscan->irel);
}
else
heap_endscan(sysscan->scan);
pfree(scan);
}
static HeapTuple
systable_getnext(void *scan)
{
SysScanDesc sysscan = (SysScanDesc) scan;
HeapTuple htup = (HeapTuple) NULL;
RetrieveIndexResult indexRes;
if (sysscan->irel)
{
if (BufferIsValid(sysscan->buffer))
{
ReleaseBuffer(sysscan->buffer);
sysscan->buffer = InvalidBuffer;
}
while (indexRes = index_getnext(sysscan->iscan, ForwardScanDirection), indexRes != NULL)
{
sysscan->tuple.t_self = indexRes->heap_iptr;
heap_fetch(sysscan->heap_rel, SnapshotNow, &sysscan->tuple, &(sysscan->buffer));
pfree(indexRes);
if (sysscan->tuple.t_data != NULL)
{
htup = &sysscan->tuple;
break;
}
}
}
else
htup = heap_getnext(sysscan->scan, 0);
return htup;
}
/*
* find a specified attribute in a node entry
*/
static bool
find_attribute_walker(Node *node, int *attnump)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == 0 && var->varno == 1 &&
var->varattno == *attnump)
return true;
}
return expression_tree_walker(node, find_attribute_walker,
(void *) attnump);
}
static bool
find_attribute_in_node(Node *node, int attnum)
{
return find_attribute_walker(node, &attnum);
}
/*
* Remove/check references for the column
*/
static bool
RemoveColumnReferences(Oid reloid, int attnum, bool checkonly, HeapTuple reltup)
{
Relation indexRelation,
rcrel;
ScanKeyData entry;
HeapScanDesc scan;
void *sysscan;
HeapTuple htup,
indexTuple;
Form_pg_index index;
Form_pg_class pgcform = (Form_pg_class) NULL;
int i;
bool checkok = true;
if (!checkonly)
pgcform = (Form_pg_class) GETSTRUCT(reltup);
/*
* Remove/check constraints here
*/
ScanKeyEntryInitialize(&entry, (bits16) 0x0, Anum_pg_relcheck_rcrelid,
(RegProcedure) F_OIDEQ, ObjectIdGetDatum(reloid));
rcrel = heap_openr(RelCheckRelationName, RowExclusiveLock);
sysscan = systable_beginscan(rcrel, RelCheckIndex, 1, &entry);
while (HeapTupleIsValid(htup = systable_getnext(sysscan)))
{
Form_pg_relcheck relcheck;
char *ccbin;
Node *node;
relcheck = (Form_pg_relcheck) GETSTRUCT(htup);
ccbin = DatumGetCString(DirectFunctionCall1(textout,
PointerGetDatum(&relcheck->rcbin)));
node = stringToNode(ccbin);
pfree(ccbin);
if (find_attribute_in_node(node, attnum))
{
if (checkonly)
{
checkok = false;
elog(ERROR, "target column is used in a constraint");
}
else
{
simple_heap_delete(rcrel, &htup->t_self);
pgcform->relchecks--;
}
}
}
systable_endscan(sysscan);
heap_close(rcrel, NoLock);
/*
* What to do with triggers/rules/views/procedues ?
*/
/*
* Remove/check indexes
*/
indexRelation = heap_openr(IndexRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&entry, 0, Anum_pg_index_indrelid, F_OIDEQ,
ObjectIdGetDatum(reloid));
scan = heap_beginscan(indexRelation, false, SnapshotNow, 1, &entry);
while (HeapTupleIsValid(indexTuple = heap_getnext(scan, 0)))
{
index = (Form_pg_index) GETSTRUCT(indexTuple);
for (i = 0; i < INDEX_MAX_KEYS; i++)
{
if (index->indkey[i] == InvalidAttrNumber)
break;
else if (index->indkey[i] == attnum)
{
if (checkonly)
{
checkok = false;
elog(ERROR, "target column is used in an index");
}
else
{
htup = SearchSysCache(RELOID,
ObjectIdGetDatum(index->indexrelid),
0, 0, 0);
RemoveIndex(NameStr(((Form_pg_class) GETSTRUCT(htup))->relname));
ReleaseSysCache(htup);
}
break;
}
}
}
heap_endscan(scan);
heap_close(indexRelation, NoLock);
return checkok;
}
#endif /* _DROP_COLUMN_HACK__ */
/*
* ALTER TABLE DROP COLUMN
*/
void
AlterTableDropColumn(const char *relationName,
bool inh, const char *colName,
int behavior)
{
#ifdef _DROP_COLUMN_HACK__
Relation rel,
attrdesc;
Oid myrelid;
HeapTuple reltup;
HeapTupleData classtuple;
Buffer buffer;
Form_pg_attribute attribute;
HeapTuple tup;
Relation idescs[Num_pg_attr_indices];
int attnum;
bool hasindex;
char dropColname[32];
if (inh)
elog(ERROR, "ALTER TABLE / DROP COLUMN with inherit option is not supported yet");
/*
* permissions checking. this would normally be done in utility.c,
* but this particular routine is recursive.
*
* normally, only the owner of a class can change its schema.
*/
if (!allowSystemTableMods && IsSystemRelationName(relationName))
elog(ERROR, "ALTER TABLE: relation \"%s\" is a system catalog",
relationName);
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
/*
* Grab an exclusive lock on the target table, which we will NOT
* release until end of transaction.
*/
rel = heap_openr(relationName, AccessExclusiveLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
relationName);
myrelid = RelationGetRelid(rel);
heap_close(rel, NoLock); /* close rel but keep lock! */
/*
* What to do when rel has inheritors ?
*/
if (length(find_all_inheritors(myrelid)) > 1)
elog(ERROR, "ALTER TABLE: cannot drop a column on table that is inherited from");
/*
* lock the pg_class tuple for update
*/
rel = heap_openr(RelationRelationName, RowExclusiveLock);
reltup = SearchSysCache(RELNAME,
PointerGetDatum(relationName),
0, 0, 0);
if (!HeapTupleIsValid(reltup))
elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
relationName);
classtuple.t_self = reltup->t_self;
ReleaseSysCache(reltup);
switch (heap_mark4update(rel, &classtuple, &buffer))
{
case HeapTupleSelfUpdated:
case HeapTupleMayBeUpdated:
break;
default:
elog(ERROR, "couldn't lock pg_class tuple");
}
reltup = heap_copytuple(&classtuple);
ReleaseBuffer(buffer);
attrdesc = heap_openr(AttributeRelationName, RowExclusiveLock);
/*
* Get the target pg_attribute tuple and make a modifiable copy
*/
tup = SearchSysCacheCopy(ATTNAME,
ObjectIdGetDatum(reltup->t_data->t_oid),
PointerGetDatum(colName),
0, 0);
if (!HeapTupleIsValid(tup))
elog(ERROR, "ALTER TABLE: column name \"%s\" doesn't exist in table \"%s\"",
colName, relationName);
attribute = (Form_pg_attribute) GETSTRUCT(tup);
attnum = attribute->attnum;
if (attnum <= 0)
elog(ERROR, "ALTER TABLE: column name \"%s\" was already dropped",
colName);
/*
* Check constraints/indices etc here
*/
if (behavior != CASCADE)
{
if (!RemoveColumnReferences(myrelid, attnum, true, NULL))
elog(ERROR, "the column is referenced");
}
/*
* change the target pg_attribute tuple
*/
sprintf(dropColname, "*already Dropped*%d", attnum);
namestrcpy(&(attribute->attname), dropColname);
ATTRIBUTE_DROP_COLUMN(attribute);
simple_heap_update(attrdesc, &tup->t_self, tup);
hasindex = (!IsIgnoringSystemIndexes() && RelationGetForm(attrdesc)->relhasindex);
if (hasindex)
{
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_attr_indices,
attrdesc, tup);
CatalogCloseIndices(Num_pg_attr_indices, idescs);
}
heap_close(attrdesc, NoLock);
heap_freetuple(tup);
/* delete comment for this attribute only */
CreateComments(RelationGetRelid(rel), RelOid_pg_class,
(int32) attnum, NULL);
/* delete attrdef */
drop_default(myrelid, attnum);
/*
* Remove objects which reference this column
*/
if (behavior == CASCADE)
{
Relation ridescs[Num_pg_class_indices];
RemoveColumnReferences(myrelid, attnum, false, reltup);
/* update pg_class tuple */
simple_heap_update(rel, &reltup->t_self, reltup);
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, ridescs);
CatalogIndexInsert(ridescs, Num_pg_class_indices, rel, reltup);
CatalogCloseIndices(Num_pg_class_indices, ridescs);
}
heap_freetuple(reltup);
heap_close(rel, NoLock);
#else
elog(ERROR, "ALTER TABLE / DROP COLUMN is not implemented");
#endif /* _DROP_COLUMN_HACK__ */
}
/*
* ALTER TABLE ADD CONSTRAINT
*/
void
AlterTableAddConstraint(char *relationName,
bool inh, List *newConstraints)
{
Relation rel;
Oid myrelid;
List *listptr;
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
/* Disallow ADD CONSTRAINT on views, indexes, sequences, etc */
if (!is_relation(relationName))
elog(ERROR, "ALTER TABLE ADD CONSTRAINT: %s is not a table",
relationName);
rel = heap_openr(relationName, AccessExclusiveLock);
myrelid = RelationGetRelid(rel);
if (inh) {
List *child,
*children;
/* this routine is actually in the planner */
children = find_all_inheritors(myrelid);
/*
* find_all_inheritors does the recursive search of the
* inheritance hierarchy, so all we have to do is process all
* of the relids in the list that it returns.
*/
foreach(child, children)
{
Oid childrelid = lfirsti(child);
char *childrelname;
Relation childrel;
if (childrelid == myrelid)
continue;
childrel = heap_open(childrelid, AccessExclusiveLock);
childrelname = pstrdup(RelationGetRelationName(childrel));
heap_close(childrel, AccessExclusiveLock);
AlterTableAddConstraint(childrelname, false, newConstraints);
pfree(childrelname);
}
}
foreach(listptr, newConstraints)
{
Node *newConstraint = lfirst(listptr);
switch (nodeTag(newConstraint))
{
case T_Constraint:
{
Constraint *constr = (Constraint *) newConstraint;
switch (constr->contype)
{
case CONSTR_CHECK:
{
ParseState *pstate;
bool successful = true;
HeapScanDesc scan;
ExprContext *econtext;
TupleTableSlot *slot;
HeapTuple tuple;
RangeTblEntry *rte;
List *qual;
Node *expr;
char *name;
if (constr->name)
name = constr->name;
else
name = "<unnamed>";
/*
* We need to make a parse state and range
* table to allow us to transformExpr and
* fix_opids to get a version of the
* expression we can pass to ExecQual
*/
pstate = make_parsestate(NULL);
rte = addRangeTableEntry(pstate, relationName, NULL,
false, true);
addRTEtoQuery(pstate, rte, true, true);
/* Convert the A_EXPR in raw_expr into an EXPR */
expr = transformExpr(pstate, constr->raw_expr,
EXPR_COLUMN_FIRST);
/*
* Make sure it yields a boolean result.
*/
if (exprType(expr) != BOOLOID)
elog(ERROR, "CHECK '%s' does not yield boolean result",
name);
/*
* Make sure no outside relations are referred
* to.
*/
if (length(pstate->p_rtable) != 1)
elog(ERROR, "Only relation '%s' can be referenced in CHECK",
relationName);
/*
* Might as well try to reduce any constant
* expressions.
*/
expr = eval_const_expressions(expr);
/* And fix the opids */
fix_opids(expr);
qual = makeList1(expr);
/* Make tuple slot to hold tuples */
slot = MakeTupleTableSlot();
ExecSetSlotDescriptor(slot, RelationGetDescr(rel), false);
/* Make an expression context for ExecQual */
econtext = MakeExprContext(slot, CurrentMemoryContext);
/*
* Scan through the rows now, checking the
* expression at each row.
*/
scan = heap_beginscan(rel, false, SnapshotNow, 0, NULL);
while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
{
ExecStoreTuple(tuple, slot, InvalidBuffer, false);
if (!ExecQual(qual, econtext, true))
{
successful = false;
break;
}
ResetExprContext(econtext);
}
heap_endscan(scan);
FreeExprContext(econtext);
pfree(slot);
if (!successful)
elog(ERROR, "AlterTableAddConstraint: rejected due to CHECK constraint %s", name);
/*
* Call AddRelationRawConstraints to do the
* real adding -- It duplicates some of the
* above, but does not check the validity of
* the constraint against tuples already in
* the table.
*/
AddRelationRawConstraints(rel, NIL,
makeList1(constr));
break;
}
case CONSTR_UNIQUE:
{
char *iname = constr->name;
bool istemp = is_temp_rel_name(relationName);
List *indexoidlist;
List *indexoidscan;
int num_keys;
bool index_found = false;
bool index_found_unique = false;
bool index_found_primary = false;
/* If the constraint name is not specified, generate a name */
if (iname == NULL) {
Oid indoid;
int pass = 0;
char *typename = palloc(NAMEDATALEN);
Ident *key;
/* Assume that the length of the attr list is already > 0 */
/* Get the first attribute so we can use its name */
key = (Ident *)lfirst(constr->keys);
/* Initialise typename to 'key' */
snprintf(typename, NAMEDATALEN, "key");
for (;;)
{
iname = makeObjectName(relationName, key->name, typename);
/* Check for a conflict */
indoid = RelnameFindRelid(iname);
/* If the oid was not found, then we have a safe name */
if ((!istemp && !OidIsValid(indoid)) ||
(istemp && !is_temp_rel_name(iname)))
break;
/* Found a conflict, so try a new name component */
pfree(iname);
snprintf(typename, NAMEDATALEN, "key%d", ++pass);
}
}
/* Need to check for unique key already on field(s) */
/*
* First we check for limited correctness of the
* constraint
*/
/* Loop over all indices on the relation */
indexoidlist = RelationGetIndexList(rel);
foreach(indexoidscan, indexoidlist)
{
Oid indexoid = lfirsti(indexoidscan);
HeapTuple indexTuple;
Form_pg_index indexStruct;
List *keyl;
int i;
indexTuple = SearchSysCache(INDEXRELID,
ObjectIdGetDatum(indexoid),
0, 0, 0);
if (!HeapTupleIsValid(indexTuple))
elog(ERROR, "ALTER TABLE/ADD CONSTRAINT: Index \"%u\" not found",
indexoid);
indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
/*
* Make sure this index has the same number of
* keys as the constraint -- It obviously won't match otherwise.
*/
for (i = 0; i < INDEX_MAX_KEYS && indexStruct->indkey[i] != 0; i++)
;
num_keys = length(constr->keys);
if (i == num_keys)
{
/* Loop over each key in the constraint and check that there is a
corresponding key in the index. */
int keys_matched = 0;
i = 0;
foreach(keyl, constr->keys)
{
Ident *key = lfirst(keyl);
int keyno = indexStruct->indkey[i];
/* Look at key[i] in the index and check that it is over the same column
as key[i] in the constraint. This is to differentiate between (a,b)
and (b,a) */
if (namestrcmp(attnumAttName(rel, keyno),
key->name) == 0)
keys_matched++;
else
break;
i++;
}
if (keys_matched == num_keys) {
index_found = true;
index_found_unique = indexStruct->indisunique;
index_found_primary = indexStruct->indisprimary;
}
}
ReleaseSysCache(indexTuple);
if (index_found_unique || index_found_primary)
break;
}
freeList(indexoidlist);
if (index_found_primary)
elog(ERROR, "Unique primary key already defined on relation \"%s\"", relationName);
else if (index_found_unique)
elog(ERROR, "Unique constraint already defined on the specified attributes in relation \"%s\"", relationName);
/* If everything is ok, create the new index (constraint) */
DefineIndex(
relationName,
iname,
"btree",
constr->keys,
true,
false,
NULL,
NIL);
/* Issue notice */
elog(NOTICE, "ALTER TABLE/ADD UNIQUE will create implicit index '%s' for table '%s'",
iname, relationName);
if (index_found)
elog(NOTICE, "Unique constraint supercedes existing index on relation \"%s\". Drop the existing index to remove redundancy.", relationName);
pfree(iname);
break;
}
default:
elog(ERROR, "ALTER TABLE / ADD CONSTRAINT is not implemented for that constraint type.");
}
break;
}
case T_FkConstraint:
{
FkConstraint *fkconstraint = (FkConstraint *) newConstraint;
Relation pkrel;
HeapScanDesc scan;
HeapTuple tuple;
Trigger trig;
List *list;
int count;
if (is_temp_rel_name(fkconstraint->pktable_name) &&
!is_temp_rel_name(relationName))
elog(ERROR, "ALTER TABLE / ADD CONSTRAINT: Unable to reference temporary table from permanent table constraint.");
/*
* Grab an exclusive lock on the pk table, so that someone
* doesn't delete rows out from under us.
*/
pkrel = heap_openr(fkconstraint->pktable_name, AccessExclusiveLock);
if (pkrel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "referenced table \"%s\" not a relation",
fkconstraint->pktable_name);
heap_close(pkrel, NoLock);
/*
* First we check for limited correctness of the constraint.
*
* NOTE: we assume parser has already checked for existence
* of an appropriate unique index on the referenced relation,
* and that the column datatypes are comparable.
*
* Scan through each tuple, calling the RI_FKey_Match_Ins
* (insert trigger) as if that tuple had just been
* inserted. If any of those fail, it should elog(ERROR)
* and that's that.
*/
trig.tgoid = 0;
if (fkconstraint->constr_name)
trig.tgname = fkconstraint->constr_name;
else
trig.tgname = "<unknown>";
trig.tgfoid = 0;
trig.tgtype = 0;
trig.tgenabled = TRUE;
trig.tgisconstraint = TRUE;
trig.tginitdeferred = FALSE;
trig.tgdeferrable = FALSE;
trig.tgargs = (char **) palloc(
sizeof(char *) * (4 + length(fkconstraint->fk_attrs)
+ length(fkconstraint->pk_attrs)));
if (fkconstraint->constr_name)
trig.tgargs[0] = fkconstraint->constr_name;
else
trig.tgargs[0] = "<unknown>";
trig.tgargs[1] = (char *) relationName;
trig.tgargs[2] = fkconstraint->pktable_name;
trig.tgargs[3] = fkconstraint->match_type;
count = 4;
foreach(list, fkconstraint->fk_attrs)
{
Ident *fk_at = lfirst(list);
trig.tgargs[count] = fk_at->name;
count += 2;
}
count = 5;
foreach(list, fkconstraint->pk_attrs)
{
Ident *pk_at = lfirst(list);
trig.tgargs[count] = pk_at->name;
count += 2;
}
trig.tgnargs = count - 1;
scan = heap_beginscan(rel, false, SnapshotNow, 0, NULL);
while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
{
/* Make a call to the check function */
/* No parameters are passed, but we do set a context */
FunctionCallInfoData fcinfo;
TriggerData trigdata;
MemSet(&fcinfo, 0, sizeof(fcinfo));
/* We assume RI_FKey_check_ins won't look at flinfo... */
trigdata.type = T_TriggerData;
trigdata.tg_event = TRIGGER_EVENT_INSERT | TRIGGER_EVENT_ROW;
trigdata.tg_relation = rel;
trigdata.tg_trigtuple = tuple;
trigdata.tg_newtuple = NULL;
trigdata.tg_trigger = &trig;
fcinfo.context = (Node *) &trigdata;
RI_FKey_check_ins(&fcinfo);
}
heap_endscan(scan);
pfree(trig.tgargs);
break;
}
default:
elog(ERROR, "ALTER TABLE / ADD CONSTRAINT unable to determine type of constraint passed");
}
}
/* Close rel, but keep lock till commit */
heap_close(rel, NoLock);
}
/*
* ALTER TABLE DROP CONSTRAINT
* Note: It is legal to remove a constraint with name "" as it is possible
* to add a constraint with name "".
* Christopher Kings-Lynne
*/
void
AlterTableDropConstraint(const char *relationName,
bool inh, const char *constrName,
int behavior)
{
Relation rel;
int deleted;
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
/* We don't support CASCADE yet - in fact, RESTRICT
* doesn't work to the spec either! */
if (behavior == CASCADE)
elog(ERROR, "ALTER TABLE / DROP CONSTRAINT does not support the CASCADE keyword");
/*
* Acquire an exclusive lock on the target relation for
* the duration of the operation.
*/
rel = heap_openr(relationName, AccessExclusiveLock);
/* Disallow DROP CONSTRAINT on views, indexes, sequences, etc */
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE / DROP CONSTRAINT: %s is not a table",
relationName);
/*
* Since all we have is the name of the constraint, we have to look through
* all catalogs that could possibly contain a constraint for this relation.
* We also keep a count of the number of constraints removed.
*/
deleted = 0;
/*
* First, we remove all CHECK constraints with the given name
*/
deleted += RemoveCheckConstraint(rel, constrName, inh);
/*
* Now we remove NULL, UNIQUE, PRIMARY KEY and FOREIGN KEY constraints.
*
* Unimplemented.
*/
/* Close the target relation */
heap_close(rel, NoLock);
/* If zero constraints deleted, complain */
if (deleted == 0)
elog(ERROR, "ALTER TABLE / DROP CONSTRAINT: %s does not exist",
constrName);
/* Otherwise if more than one constraint deleted, notify */
else if (deleted > 1)
elog(NOTICE, "Multiple constraints dropped");
}
/*
* ALTER TABLE OWNER
*/
void
AlterTableOwner(const char *relationName, const char *newOwnerName)
{
Relation class_rel;
HeapTuple tuple;
int32 newOwnerSysid;
Relation idescs[Num_pg_class_indices];
/*
* first check that we are a superuser
*/
if (!superuser())
elog(ERROR, "ALTER TABLE: permission denied");
/*
* look up the new owner in pg_shadow and get the sysid
*/
newOwnerSysid = get_usesysid(newOwnerName);
/*
* find the table's entry in pg_class and make a modifiable copy
*/
class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
tuple = SearchSysCacheCopy(RELNAME,
PointerGetDatum(relationName),
0, 0, 0);
if (!HeapTupleIsValid(tuple))
elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
relationName);
switch (((Form_pg_class) GETSTRUCT(tuple))->relkind)
{
case RELKIND_RELATION:
case RELKIND_INDEX:
case RELKIND_VIEW:
case RELKIND_SEQUENCE:
/* ok to change owner */
break;
default:
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table, index, view, or sequence",
relationName);
}
/*
* modify the table's entry and write to the heap
*/
((Form_pg_class) GETSTRUCT(tuple))->relowner = newOwnerSysid;
simple_heap_update(class_rel, &tuple->t_self, tuple);
/* Keep the catalog indices up to date */
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_class_indices, class_rel, tuple);
CatalogCloseIndices(Num_pg_class_indices, idescs);
/*
* unlock everything and return
*/
heap_freetuple(tuple);
heap_close(class_rel, NoLock);
}
/*
* ALTER TABLE CREATE TOAST TABLE
*/
void
AlterTableCreateToastTable(const char *relationName, bool silent)
{
Relation rel;
Oid myrelid;
HeapTuple reltup;
HeapTupleData classtuple;
TupleDesc tupdesc;
Relation class_rel;
Buffer buffer;
Relation ridescs[Num_pg_class_indices];
Oid toast_relid;
Oid toast_idxid;
char toast_relname[NAMEDATALEN + 1];
char toast_idxname[NAMEDATALEN + 1];
IndexInfo *indexInfo;
Oid classObjectId[2];
/*
* permissions checking. XXX exactly what is appropriate here?
*/
#ifndef NO_SECURITY
if (!pg_ownercheck(GetUserId(), relationName, RELNAME))
elog(ERROR, "ALTER TABLE: permission denied");
#endif
/*
* Grab an exclusive lock on the target table, which we will NOT
* release until end of transaction.
*/
rel = heap_openr(relationName, AccessExclusiveLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
relationName);
myrelid = RelationGetRelid(rel);
/*
* lock the pg_class tuple for update (is that really needed?)
*/
class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
reltup = SearchSysCache(RELNAME,
PointerGetDatum(relationName),
0, 0, 0);
if (!HeapTupleIsValid(reltup))
elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
relationName);
classtuple.t_self = reltup->t_self;
ReleaseSysCache(reltup);
switch (heap_mark4update(class_rel, &classtuple, &buffer))
{
case HeapTupleSelfUpdated:
case HeapTupleMayBeUpdated:
break;
default:
elog(ERROR, "couldn't lock pg_class tuple");
}
reltup = heap_copytuple(&classtuple);
ReleaseBuffer(buffer);
/*
* Is it already toasted?
*/
if (((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid != InvalidOid)
{
if (silent)
{
heap_close(rel, NoLock);
heap_close(class_rel, NoLock);
heap_freetuple(reltup);
return;
}
elog(ERROR, "ALTER TABLE: relation \"%s\" already has a toast table",
relationName);
}
/*
* Check to see whether the table actually needs a TOAST table.
*/
if (!needs_toast_table(rel))
{
if (silent)
{
heap_close(rel, NoLock);
heap_close(class_rel, NoLock);
heap_freetuple(reltup);
return;
}
elog(ERROR, "ALTER TABLE: relation \"%s\" does not need a toast table",
relationName);
}
/*
* Create the toast table and its index
*/
sprintf(toast_relname, "pg_toast_%u", myrelid);
sprintf(toast_idxname, "pg_toast_%u_idx", myrelid);
/* this is pretty painful... need a tuple descriptor */
tupdesc = CreateTemplateTupleDesc(3);
TupleDescInitEntry(tupdesc, (AttrNumber) 1,
"chunk_id",
OIDOID,
-1, 0, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 2,
"chunk_seq",
INT4OID,
-1, 0, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 3,
"chunk_data",
BYTEAOID,
-1, 0, false);
/*
* Ensure that the toast table doesn't itself get toasted, or we'll be
* toast :-(. This is essential for chunk_data because type bytea is
* toastable; hit the other two just to be sure.
*/
tupdesc->attrs[0]->attstorage = 'p';
tupdesc->attrs[1]->attstorage = 'p';
tupdesc->attrs[2]->attstorage = 'p';
/*
* Note: the toast relation is considered a "normal" relation even if
* its master relation is a temp table. There cannot be any naming
* collision, and the toast rel will be destroyed when its master is,
* so there's no need to handle the toast rel as temp.
*/
toast_relid = heap_create_with_catalog(toast_relname, tupdesc,
RELKIND_TOASTVALUE, false,
false, true);
/* make the toast relation visible, else index creation will fail */
CommandCounterIncrement();
/*
* Create unique index on chunk_id, chunk_seq.
*
* NOTE: the tuple toaster could actually function with a single-column
* index on chunk_id only. However, it couldn't be unique then. We
* want it to be unique as a check against the possibility of duplicate
* TOAST chunk OIDs. Too, the index might be a little more efficient this
* way, since btree isn't all that happy with large numbers of equal keys.
*/
indexInfo = makeNode(IndexInfo);
indexInfo->ii_NumIndexAttrs = 2;
indexInfo->ii_NumKeyAttrs = 2;
indexInfo->ii_KeyAttrNumbers[0] = 1;
indexInfo->ii_KeyAttrNumbers[1] = 2;
indexInfo->ii_Predicate = NIL;
indexInfo->ii_FuncOid = InvalidOid;
indexInfo->ii_Unique = true;
classObjectId[0] = OID_BTREE_OPS_OID;
classObjectId[1] = INT4_BTREE_OPS_OID;
toast_idxid = index_create(toast_relname, toast_idxname, indexInfo,
BTREE_AM_OID, classObjectId,
true, true);
/*
* Update toast rel's pg_class entry to show that it has an index.
* The index OID is stored into the reltoastidxid field for
* easy access by the tuple toaster.
*/
setRelhasindex(toast_relid, true, true, toast_idxid);
/*
* Store the toast table's OID in the parent relation's tuple
*/
((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid = toast_relid;
simple_heap_update(class_rel, &reltup->t_self, reltup);
/*
* Keep catalog indices current
*/
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, ridescs);
CatalogIndexInsert(ridescs, Num_pg_class_indices, class_rel, reltup);
CatalogCloseIndices(Num_pg_class_indices, ridescs);
heap_freetuple(reltup);
/*
* Close relations and make changes visible
*/
heap_close(class_rel, NoLock);
heap_close(rel, NoLock);
CommandCounterIncrement();
}
/*
* Check to see whether the table needs a TOAST table. It does only if
* (1) there are any toastable attributes, and (2) the maximum length
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
* create a toast table for something like "f1 varchar(20)".)
*/
static bool
needs_toast_table(Relation rel)
{
int32 data_length = 0;
bool maxlength_unknown = false;
bool has_toastable_attrs = false;
TupleDesc tupdesc;
Form_pg_attribute *att;
int32 tuple_length;
int i;
tupdesc = rel->rd_att;
att = tupdesc->attrs;
for (i = 0; i < tupdesc->natts; i++)
{
data_length = att_align(data_length, att[i]->attlen, att[i]->attalign);
if (att[i]->attlen >= 0)
{
/* Fixed-length types are never toastable */
data_length += att[i]->attlen;
}
else
{
int32 maxlen = type_maximum_size(att[i]->atttypid,
att[i]->atttypmod);
if (maxlen < 0)
maxlength_unknown = true;
else
data_length += maxlen;
if (att[i]->attstorage != 'p')
has_toastable_attrs = true;
}
}
if (!has_toastable_attrs)
return false; /* nothing to toast? */
if (maxlength_unknown)
return true; /* any unlimited-length attrs? */
tuple_length = MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) +
BITMAPLEN(tupdesc->natts)) +
MAXALIGN(data_length);
return (tuple_length > TOAST_TUPLE_THRESHOLD);
}
/*
*
* LOCK TABLE
*
*/
void
LockTableCommand(LockStmt *lockstmt)
{
List *p;
Relation rel;
/* Iterate over the list and open, lock, and close the relations
one at a time
*/
foreach(p, lockstmt->rellist)
{
char* relname = strVal(lfirst(p));
int aclresult;
rel = heap_openr(relname, NoLock);
if (rel->rd_rel->relkind != RELKIND_RELATION)
elog(ERROR, "LOCK TABLE: %s is not a table",
relname);
if (lockstmt->mode == AccessShareLock)
aclresult = pg_aclcheck(relname, GetUserId(),
ACL_SELECT);
else
aclresult = pg_aclcheck(relname, GetUserId(),
ACL_UPDATE | ACL_DELETE);
if (aclresult != ACLCHECK_OK)
elog(ERROR, "LOCK TABLE: permission denied");
LockRelation(rel, lockstmt->mode);
heap_close(rel, NoLock); /* close rel, keep lock */
}
}
static bool
is_relation(char *name)
{
Relation rel = heap_openr(name, NoLock);
bool retval = (rel->rd_rel->relkind == RELKIND_RELATION);
heap_close(rel, NoLock);
return retval;
}
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