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Revert "Optimize pg_visibility with read streams." 

This reverts commit ed1b1ee59f and its
followup 1c61fd8b52.  They rendered
collect_corrupt_items() unable to detect corruption.

Discussion: https://postgr.es/m/CAN55FZ1_Ru3XpMgTwsU67FTH2fs_FrRROmb7x6zs+F44QBEiww@mail.gmail.com
Discussion: https://postgr.es/m/CAEudQAozv3wTY5TV2t29JcwPydbmKbiWQkZD42S2OgzdixPMDQ@mail.gmail.com
This commit is contained in:
Noah Misch 2024-09-04 11:36:40 -07:00
parent 82b07eba9e
commit ddfc556a64
1 changed files with 21 additions and 92 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
contrib/pg_visibility/pg_visibility.c
View File

@ -21,7 +21,6 @@
#include "storage/bufmgr.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/read_stream.h"
#include "storage/smgr.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
@ -42,17 +41,6 @@ typedef struct corrupt_items
ItemPointer tids;
} corrupt_items;
/* for collect_corrupt_items_read_stream_next_block */
struct collect_corrupt_items_read_stream_private
{
bool all_frozen;
bool all_visible;
BlockNumber current_blocknum;
BlockNumber last_exclusive;
Relation rel;
Buffer vmbuffer;
};
PG_FUNCTION_INFO_V1(pg_visibility_map);
PG_FUNCTION_INFO_V1(pg_visibility_map_rel);
PG_FUNCTION_INFO_V1(pg_visibility);
@ -490,8 +478,6 @@ collect_visibility_data(Oid relid, bool include_pd)
BlockNumber blkno;
Buffer vmbuffer = InvalidBuffer;
BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
BlockRangeReadStreamPrivate p;
ReadStream *stream = NULL;
rel = relation_open(relid, AccessShareLock);
@ -503,20 +489,6 @@ collect_visibility_data(Oid relid, bool include_pd)
info->next = 0;
info->count = nblocks;
/* Create a stream if reading main fork. */
if (include_pd)
{
p.current_blocknum = 0;
p.last_exclusive = nblocks;
stream = read_stream_begin_relation(READ_STREAM_FULL,
bstrategy,
rel,
MAIN_FORKNUM,
block_range_read_stream_cb,
&p,
0);
}
for (blkno = 0; blkno < nblocks; ++blkno)
{
int32 mapbits;
@ -541,7 +513,8 @@ collect_visibility_data(Oid relid, bool include_pd)
Buffer buffer;
Page page;
buffer = read_stream_next_buffer(stream, NULL);
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
@ -552,12 +525,6 @@ collect_visibility_data(Oid relid, bool include_pd)
}
}
if (include_pd)
{
Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
read_stream_end(stream);
}
/* Clean up. */
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
@ -643,38 +610,6 @@ GetStrictOldestNonRemovableTransactionId(Relation rel)
}
}
/*
* Callback function to get next block for read stream object used in
* collect_corrupt_items() function.
*/
static BlockNumber
collect_corrupt_items_read_stream_next_block(ReadStream *stream,
void *callback_private_data,
void *per_buffer_data)
{
struct collect_corrupt_items_read_stream_private *p = callback_private_data;
for (; p->current_blocknum < p->last_exclusive; p->current_blocknum++)
{
bool check_frozen = false;
bool check_visible = false;
/* Make sure we are interruptible. */
CHECK_FOR_INTERRUPTS();
if (p->all_frozen && VM_ALL_FROZEN(p->rel, p->current_blocknum, &p->vmbuffer))
check_frozen = true;
if (p->all_visible && VM_ALL_VISIBLE(p->rel, p->current_blocknum, &p->vmbuffer))
check_visible = true;
if (!check_visible && !check_frozen)
continue;
return p->current_blocknum++;
}
return InvalidBlockNumber;
}
/*
* Returns a list of items whose visibility map information does not match
* the status of the tuples on the page.
@ -693,13 +628,12 @@ static corrupt_items *
collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
{
Relation rel;
BlockNumber nblocks;
corrupt_items *items;
BlockNumber blkno;
Buffer vmbuffer = InvalidBuffer;
BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
TransactionId OldestXmin = InvalidTransactionId;
struct collect_corrupt_items_read_stream_private p;
ReadStream *stream;
Buffer buffer;
rel = relation_open(relid, AccessShareLock);
@ -709,6 +643,8 @@ collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
if (all_visible)
OldestXmin = GetStrictOldestNonRemovableTransactionId(rel);
nblocks = RelationGetNumberOfBlocks(rel);
/*
* Guess an initial array size. We don't expect many corrupted tuples, so
* start with a small array. This function uses the "next" field to track
@ -722,46 +658,42 @@ collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
items->count = 64;
items->tids = palloc(items->count * sizeof(ItemPointerData));
p.current_blocknum = 0;
p.last_exclusive = RelationGetNumberOfBlocks(rel);
p.rel = rel;
p.vmbuffer = InvalidBuffer;
p.all_frozen = all_frozen;
p.all_visible = all_visible;
stream = read_stream_begin_relation(READ_STREAM_FULL,
bstrategy,
rel,
MAIN_FORKNUM,
collect_corrupt_items_read_stream_next_block,
&p,
0);
/* Loop over every block in the relation. */
while ((buffer = read_stream_next_buffer(stream, NULL)) != InvalidBuffer)
for (blkno = 0; blkno < nblocks; ++blkno)
{
bool check_frozen = false;
bool check_visible = false;
Buffer buffer;
Page page;
OffsetNumber offnum,
maxoff;
BlockNumber blkno;
/* Make sure we are interruptible. */
CHECK_FOR_INTERRUPTS();
/* Use the visibility map to decide whether to check this page. */
if (all_frozen && VM_ALL_FROZEN(rel, blkno, &vmbuffer))
check_frozen = true;
if (all_visible && VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
check_visible = true;
if (!check_visible && !check_frozen)
continue;
/* Read and lock the page. */
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
maxoff = PageGetMaxOffsetNumber(page);
blkno = BufferGetBlockNumber(buffer);
/*
* The visibility map bits might have changed while we were acquiring
* the page lock. Recheck to avoid returning spurious results.
*/
if (all_frozen && !VM_ALL_FROZEN(rel, blkno, &vmbuffer))
if (check_frozen && !VM_ALL_FROZEN(rel, blkno, &vmbuffer))
check_frozen = false;
if (all_visible && !VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
if (check_visible && !VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
check_visible = false;
if (!check_visible && !check_frozen)
{
@ -846,13 +778,10 @@ collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
UnlockReleaseBuffer(buffer);
}
read_stream_end(stream);
/* Clean up. */
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
if (p.vmbuffer != InvalidBuffer)
ReleaseBuffer(p.vmbuffer);
relation_close(rel, AccessShareLock);
/*