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collect_corrupt_items() failed to initialize tuple.t_self. While HeapTupleSatisfiesVacuum() doesn't actually use that value, it does Assert that it's valid, so that the code would dump core if ip_posid chanced to be zero. (That's somewhat unlikely, which probably explains how this got missed. In any case it wouldn't matter for field use.) Also, collect_corrupt_items was returning the wrong TIDs, that is the contents of t_ctid rather than the tuple's own location. This would be the same thing in simple cases, but it could be wrong if, for example, a past update attempt had been rolled back, leaving a live tuple whose t_ctid doesn't point at itself. Also, in pg_visibility(), guard against trying to read a page past the end of the rel. The VM code handles inquiries beyond the end of the map by silently returning zeroes, and it seems like we should do the same thing here. I ran into the assertion failure while using pg_visibility to check pg_upgrade's behavior, and then noted the other problems while reading the code. Report: <29043.1475288648@sss.pgh.pa.us>
750 lines
21 KiB
C
750 lines
21 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_visibility.c
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* display visibility map information and page-level visibility bits
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*
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* Copyright (c) 2016, PostgreSQL Global Development Group
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*
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* contrib/pg_visibility/pg_visibility.c
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "access/visibilitymap.h"
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#include "catalog/pg_type.h"
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#include "catalog/storage_xlog.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
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#include "storage/procarray.h"
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#include "storage/smgr.h"
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#include "utils/rel.h"
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PG_MODULE_MAGIC;
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typedef struct vbits
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{
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BlockNumber next;
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BlockNumber count;
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uint8 bits[FLEXIBLE_ARRAY_MEMBER];
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} vbits;
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typedef struct corrupt_items
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{
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BlockNumber next;
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BlockNumber count;
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ItemPointer tids;
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} corrupt_items;
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PG_FUNCTION_INFO_V1(pg_visibility_map);
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PG_FUNCTION_INFO_V1(pg_visibility_map_rel);
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PG_FUNCTION_INFO_V1(pg_visibility);
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PG_FUNCTION_INFO_V1(pg_visibility_rel);
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PG_FUNCTION_INFO_V1(pg_visibility_map_summary);
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PG_FUNCTION_INFO_V1(pg_check_frozen);
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PG_FUNCTION_INFO_V1(pg_check_visible);
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PG_FUNCTION_INFO_V1(pg_truncate_visibility_map);
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static TupleDesc pg_visibility_tupdesc(bool include_blkno, bool include_pd);
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static vbits *collect_visibility_data(Oid relid, bool include_pd);
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static corrupt_items *collect_corrupt_items(Oid relid, bool all_visible,
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bool all_frozen);
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static void record_corrupt_item(corrupt_items *items, ItemPointer tid);
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static bool tuple_all_visible(HeapTuple tup, TransactionId OldestXmin,
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Buffer buffer);
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/*
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* Visibility map information for a single block of a relation.
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*
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* Note: the VM code will silently return zeroes for pages past the end
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* of the map, so we allow probes up to MaxBlockNumber regardless of the
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* actual relation size.
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*/
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Datum
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pg_visibility_map(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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int64 blkno = PG_GETARG_INT64(1);
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int32 mapbits;
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Relation rel;
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Buffer vmbuffer = InvalidBuffer;
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TupleDesc tupdesc;
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Datum values[2];
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bool nulls[2];
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rel = relation_open(relid, AccessShareLock);
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if (blkno < 0 || blkno > MaxBlockNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid block number")));
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tupdesc = pg_visibility_tupdesc(false, false);
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MemSet(nulls, 0, sizeof(nulls));
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mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
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if (vmbuffer != InvalidBuffer)
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ReleaseBuffer(vmbuffer);
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values[0] = BoolGetDatum((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0);
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values[1] = BoolGetDatum((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0);
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relation_close(rel, AccessShareLock);
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PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
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}
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/*
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* Visibility map information for a single block of a relation, plus the
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* page-level information for the same block.
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*/
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Datum
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pg_visibility(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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int64 blkno = PG_GETARG_INT64(1);
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int32 mapbits;
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Relation rel;
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Buffer vmbuffer = InvalidBuffer;
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Buffer buffer;
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Page page;
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TupleDesc tupdesc;
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Datum values[3];
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bool nulls[3];
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rel = relation_open(relid, AccessShareLock);
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if (blkno < 0 || blkno > MaxBlockNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid block number")));
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tupdesc = pg_visibility_tupdesc(false, true);
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MemSet(nulls, 0, sizeof(nulls));
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mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
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if (vmbuffer != InvalidBuffer)
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ReleaseBuffer(vmbuffer);
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values[0] = BoolGetDatum((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0);
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values[1] = BoolGetDatum((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0);
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/* Here we have to explicitly check rel size ... */
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if (blkno < RelationGetNumberOfBlocks(rel))
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{
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buffer = ReadBuffer(rel, blkno);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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page = BufferGetPage(buffer);
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values[2] = BoolGetDatum(PageIsAllVisible(page));
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UnlockReleaseBuffer(buffer);
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}
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else
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{
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/* As with the vismap, silently return 0 for pages past EOF */
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values[2] = BoolGetDatum(false);
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}
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relation_close(rel, AccessShareLock);
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PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
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}
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/*
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* Visibility map information for every block in a relation.
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*/
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Datum
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pg_visibility_map_rel(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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vbits *info;
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if (SRF_IS_FIRSTCALL())
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{
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Oid relid = PG_GETARG_OID(0);
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MemoryContext oldcontext;
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funcctx = SRF_FIRSTCALL_INIT();
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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funcctx->tuple_desc = pg_visibility_tupdesc(true, false);
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funcctx->user_fctx = collect_visibility_data(relid, false);
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MemoryContextSwitchTo(oldcontext);
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}
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funcctx = SRF_PERCALL_SETUP();
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info = (vbits *) funcctx->user_fctx;
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if (info->next < info->count)
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{
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Datum values[3];
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bool nulls[3];
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HeapTuple tuple;
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = Int64GetDatum(info->next);
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values[1] = BoolGetDatum((info->bits[info->next] & (1 << 0)) != 0);
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values[2] = BoolGetDatum((info->bits[info->next] & (1 << 1)) != 0);
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info->next++;
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tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
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SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
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}
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SRF_RETURN_DONE(funcctx);
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}
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/*
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* Visibility map information for every block in a relation, plus the page
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* level information for each block.
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*/
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Datum
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pg_visibility_rel(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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vbits *info;
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if (SRF_IS_FIRSTCALL())
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{
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Oid relid = PG_GETARG_OID(0);
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MemoryContext oldcontext;
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funcctx = SRF_FIRSTCALL_INIT();
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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funcctx->tuple_desc = pg_visibility_tupdesc(true, true);
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funcctx->user_fctx = collect_visibility_data(relid, true);
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MemoryContextSwitchTo(oldcontext);
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}
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funcctx = SRF_PERCALL_SETUP();
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info = (vbits *) funcctx->user_fctx;
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if (info->next < info->count)
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{
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Datum values[4];
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bool nulls[4];
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HeapTuple tuple;
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = Int64GetDatum(info->next);
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values[1] = BoolGetDatum((info->bits[info->next] & (1 << 0)) != 0);
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values[2] = BoolGetDatum((info->bits[info->next] & (1 << 1)) != 0);
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values[3] = BoolGetDatum((info->bits[info->next] & (1 << 2)) != 0);
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info->next++;
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tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
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SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
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}
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SRF_RETURN_DONE(funcctx);
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}
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/*
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* Count the number of all-visible and all-frozen pages in the visibility
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* map for a particular relation.
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*/
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Datum
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pg_visibility_map_summary(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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Relation rel;
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BlockNumber nblocks;
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BlockNumber blkno;
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Buffer vmbuffer = InvalidBuffer;
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int64 all_visible = 0;
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int64 all_frozen = 0;
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TupleDesc tupdesc;
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Datum values[2];
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bool nulls[2];
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rel = relation_open(relid, AccessShareLock);
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nblocks = RelationGetNumberOfBlocks(rel);
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for (blkno = 0; blkno < nblocks; ++blkno)
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{
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int32 mapbits;
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/* Make sure we are interruptible. */
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CHECK_FOR_INTERRUPTS();
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/* Get map info. */
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mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
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if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
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++all_visible;
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if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
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++all_frozen;
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}
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/* Clean up. */
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if (vmbuffer != InvalidBuffer)
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ReleaseBuffer(vmbuffer);
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relation_close(rel, AccessShareLock);
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tupdesc = CreateTemplateTupleDesc(2, false);
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TupleDescInitEntry(tupdesc, (AttrNumber) 1, "all_visible", INT8OID, -1, 0);
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TupleDescInitEntry(tupdesc, (AttrNumber) 2, "all_frozen", INT8OID, -1, 0);
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tupdesc = BlessTupleDesc(tupdesc);
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = Int64GetDatum(all_visible);
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values[1] = Int64GetDatum(all_frozen);
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PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
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}
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/*
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* Return the TIDs of non-frozen tuples present in pages marked all-frozen
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* in the visibility map. We hope no one will ever find any, but there could
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* be bugs, database corruption, etc.
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*/
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Datum
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pg_check_frozen(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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corrupt_items *items;
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if (SRF_IS_FIRSTCALL())
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{
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Oid relid = PG_GETARG_OID(0);
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MemoryContext oldcontext;
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funcctx = SRF_FIRSTCALL_INIT();
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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funcctx->user_fctx = collect_corrupt_items(relid, false, true);
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MemoryContextSwitchTo(oldcontext);
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}
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funcctx = SRF_PERCALL_SETUP();
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items = (corrupt_items *) funcctx->user_fctx;
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if (items->next < items->count)
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SRF_RETURN_NEXT(funcctx, PointerGetDatum(&items->tids[items->next++]));
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SRF_RETURN_DONE(funcctx);
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}
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/*
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* Return the TIDs of not-all-visible tuples in pages marked all-visible
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* in the visibility map. We hope no one will ever find any, but there could
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* be bugs, database corruption, etc.
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*/
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Datum
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pg_check_visible(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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corrupt_items *items;
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if (SRF_IS_FIRSTCALL())
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{
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Oid relid = PG_GETARG_OID(0);
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MemoryContext oldcontext;
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funcctx = SRF_FIRSTCALL_INIT();
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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funcctx->user_fctx = collect_corrupt_items(relid, true, false);
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MemoryContextSwitchTo(oldcontext);
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}
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funcctx = SRF_PERCALL_SETUP();
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items = (corrupt_items *) funcctx->user_fctx;
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if (items->next < items->count)
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SRF_RETURN_NEXT(funcctx, PointerGetDatum(&items->tids[items->next++]));
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SRF_RETURN_DONE(funcctx);
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}
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/*
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* Remove the visibility map fork for a relation. If there turn out to be
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* any bugs in the visibility map code that require rebuilding the VM, this
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* provides users with a way to do it that is cleaner than shutting down the
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* server and removing files by hand.
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*
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* This is a cut-down version of RelationTruncate.
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*/
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Datum
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pg_truncate_visibility_map(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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Relation rel;
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rel = relation_open(relid, AccessExclusiveLock);
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if (rel->rd_rel->relkind != RELKIND_RELATION &&
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rel->rd_rel->relkind != RELKIND_MATVIEW &&
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rel->rd_rel->relkind != RELKIND_TOASTVALUE)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a table, materialized view, or TOAST table",
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RelationGetRelationName(rel))));
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RelationOpenSmgr(rel);
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rel->rd_smgr->smgr_vm_nblocks = InvalidBlockNumber;
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visibilitymap_truncate(rel, 0);
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if (RelationNeedsWAL(rel))
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{
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xl_smgr_truncate xlrec;
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xlrec.blkno = 0;
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xlrec.rnode = rel->rd_node;
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xlrec.flags = SMGR_TRUNCATE_VM;
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XLogBeginInsert();
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XLogRegisterData((char *) &xlrec, sizeof(xlrec));
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XLogInsert(RM_SMGR_ID, XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
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}
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/*
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* Release the lock right away, not at commit time.
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*
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* It would be a problem to release the lock prior to commit if this
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* truncate operation sends any transactional invalidation messages. Other
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* backends would potentially be able to lock the relation without
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* processing them in the window of time between when we release the lock
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* here and when we sent the messages at our eventual commit. However,
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* we're currently only sending a non-transactional smgr invalidation,
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* which will have been posted to shared memory immediately from within
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* visibilitymap_truncate. Therefore, there should be no race here.
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*
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* The reason why it's desirable to release the lock early here is because
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* of the possibility that someone will need to use this to blow away many
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* visibility map forks at once. If we can't release the lock until
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* commit time, the transaction doing this will accumulate
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* AccessExclusiveLocks on all of those relations at the same time, which
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* is undesirable. However, if this turns out to be unsafe we may have no
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* choice...
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*/
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relation_close(rel, AccessExclusiveLock);
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/* Nothing to return. */
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PG_RETURN_VOID();
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}
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/*
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* Helper function to construct whichever TupleDesc we need for a particular
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* call.
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*/
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static TupleDesc
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pg_visibility_tupdesc(bool include_blkno, bool include_pd)
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{
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TupleDesc tupdesc;
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AttrNumber maxattr = 2;
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AttrNumber a = 0;
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if (include_blkno)
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++maxattr;
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if (include_pd)
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++maxattr;
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tupdesc = CreateTemplateTupleDesc(maxattr, false);
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if (include_blkno)
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TupleDescInitEntry(tupdesc, ++a, "blkno", INT8OID, -1, 0);
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TupleDescInitEntry(tupdesc, ++a, "all_visible", BOOLOID, -1, 0);
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TupleDescInitEntry(tupdesc, ++a, "all_frozen", BOOLOID, -1, 0);
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if (include_pd)
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TupleDescInitEntry(tupdesc, ++a, "pd_all_visible", BOOLOID, -1, 0);
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Assert(a == maxattr);
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return BlessTupleDesc(tupdesc);
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}
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/*
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* Collect visibility data about a relation.
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*/
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static vbits *
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collect_visibility_data(Oid relid, bool include_pd)
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{
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Relation rel;
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BlockNumber nblocks;
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vbits *info;
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BlockNumber blkno;
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Buffer vmbuffer = InvalidBuffer;
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BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
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rel = relation_open(relid, AccessShareLock);
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nblocks = RelationGetNumberOfBlocks(rel);
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info = palloc0(offsetof(vbits, bits) +nblocks);
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info->next = 0;
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info->count = nblocks;
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for (blkno = 0; blkno < nblocks; ++blkno)
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{
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int32 mapbits;
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/* Make sure we are interruptible. */
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CHECK_FOR_INTERRUPTS();
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/* Get map info. */
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mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
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if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
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info->bits[blkno] |= (1 << 0);
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if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
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info->bits[blkno] |= (1 << 1);
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/*
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* Page-level data requires reading every block, so only get it if the
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* caller needs it. Use a buffer access strategy, too, to prevent
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* cache-trashing.
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*/
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if (include_pd)
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{
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Buffer buffer;
|
|
Page page;
|
|
|
|
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
|
|
bstrategy);
|
|
LockBuffer(buffer, BUFFER_LOCK_SHARE);
|
|
|
|
page = BufferGetPage(buffer);
|
|
if (PageIsAllVisible(page))
|
|
info->bits[blkno] |= (1 << 2);
|
|
|
|
UnlockReleaseBuffer(buffer);
|
|
}
|
|
}
|
|
|
|
/* Clean up. */
|
|
if (vmbuffer != InvalidBuffer)
|
|
ReleaseBuffer(vmbuffer);
|
|
relation_close(rel, AccessShareLock);
|
|
|
|
return info;
|
|
}
|
|
|
|
/*
|
|
* Returns a list of items whose visibility map information does not match
|
|
* the status of the tuples on the page.
|
|
*
|
|
* If all_visible is passed as true, this will include all items which are
|
|
* on pages marked as all-visible in the visibility map but which do not
|
|
* seem to in fact be all-visible.
|
|
*
|
|
* If all_frozen is passed as true, this will include all items which are
|
|
* on pages marked as all-frozen but which do not seem to in fact be frozen.
|
|
*/
|
|
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;
|
|
|
|
if (all_visible)
|
|
{
|
|
/* Don't pass rel; that will fail in recovery. */
|
|
OldestXmin = GetOldestXmin(NULL, true);
|
|
}
|
|
|
|
rel = relation_open(relid, AccessShareLock);
|
|
|
|
if (rel->rd_rel->relkind != RELKIND_RELATION &&
|
|
rel->rd_rel->relkind != RELKIND_MATVIEW &&
|
|
rel->rd_rel->relkind != RELKIND_TOASTVALUE)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
|
|
errmsg("\"%s\" is not a table, materialized view, or TOAST table",
|
|
RelationGetRelationName(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
|
|
* the next offset where we can store an item (which is the same thing as
|
|
* the number of items found so far) and the "count" field to track the
|
|
* number of entries allocated. We'll repurpose these fields before
|
|
* returning.
|
|
*/
|
|
items = palloc0(sizeof(corrupt_items));
|
|
items->next = 0;
|
|
items->count = 64;
|
|
items->tids = palloc(items->count * sizeof(ItemPointerData));
|
|
|
|
/* Loop over every block in the relation. */
|
|
for (blkno = 0; blkno < nblocks; ++blkno)
|
|
{
|
|
bool check_frozen = false;
|
|
bool check_visible = false;
|
|
Buffer buffer;
|
|
Page page;
|
|
OffsetNumber offnum,
|
|
maxoff;
|
|
|
|
/* 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);
|
|
|
|
/*
|
|
* The visibility map bits might have changed while we were acquiring
|
|
* the page lock. Recheck to avoid returning spurious results.
|
|
*/
|
|
if (check_frozen && !VM_ALL_FROZEN(rel, blkno, &vmbuffer))
|
|
check_frozen = false;
|
|
if (check_visible && !VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
|
|
check_visible = false;
|
|
if (!check_visible && !check_frozen)
|
|
{
|
|
UnlockReleaseBuffer(buffer);
|
|
continue;
|
|
}
|
|
|
|
/* Iterate over each tuple on the page. */
|
|
for (offnum = FirstOffsetNumber;
|
|
offnum <= maxoff;
|
|
offnum = OffsetNumberNext(offnum))
|
|
{
|
|
HeapTupleData tuple;
|
|
ItemId itemid;
|
|
|
|
itemid = PageGetItemId(page, offnum);
|
|
|
|
/* Unused or redirect line pointers are of no interest. */
|
|
if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid))
|
|
continue;
|
|
|
|
/* Dead line pointers are neither all-visible nor frozen. */
|
|
if (ItemIdIsDead(itemid))
|
|
{
|
|
ItemPointerSet(&(tuple.t_self), blkno, offnum);
|
|
record_corrupt_item(items, &tuple.t_self);
|
|
continue;
|
|
}
|
|
|
|
/* Initialize a HeapTupleData structure for checks below. */
|
|
ItemPointerSet(&(tuple.t_self), blkno, offnum);
|
|
tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
|
|
tuple.t_len = ItemIdGetLength(itemid);
|
|
tuple.t_tableOid = relid;
|
|
|
|
/*
|
|
* If we're checking whether the page is all-visible, we expect
|
|
* the tuple to be all-visible.
|
|
*/
|
|
if (check_visible &&
|
|
!tuple_all_visible(&tuple, OldestXmin, buffer))
|
|
{
|
|
TransactionId RecomputedOldestXmin;
|
|
|
|
/*
|
|
* Time has passed since we computed OldestXmin, so it's
|
|
* possible that this tuple is all-visible in reality even
|
|
* though it doesn't appear so based on our
|
|
* previously-computed value. Let's compute a new value so we
|
|
* can be certain whether there is a problem.
|
|
*
|
|
* From a concurrency point of view, it sort of sucks to
|
|
* retake ProcArrayLock here while we're holding the buffer
|
|
* exclusively locked, but it should be safe against
|
|
* deadlocks, because surely GetOldestXmin() should never take
|
|
* a buffer lock. And this shouldn't happen often, so it's
|
|
* worth being careful so as to avoid false positives.
|
|
*/
|
|
RecomputedOldestXmin = GetOldestXmin(NULL, true);
|
|
|
|
if (!TransactionIdPrecedes(OldestXmin, RecomputedOldestXmin))
|
|
record_corrupt_item(items, &tuple.t_self);
|
|
else
|
|
{
|
|
OldestXmin = RecomputedOldestXmin;
|
|
if (!tuple_all_visible(&tuple, OldestXmin, buffer))
|
|
record_corrupt_item(items, &tuple.t_self);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we're checking whether the page is all-frozen, we expect the
|
|
* tuple to be in a state where it will never need freezing.
|
|
*/
|
|
if (check_frozen)
|
|
{
|
|
if (heap_tuple_needs_eventual_freeze(tuple.t_data))
|
|
record_corrupt_item(items, &tuple.t_self);
|
|
}
|
|
}
|
|
|
|
UnlockReleaseBuffer(buffer);
|
|
}
|
|
|
|
/* Clean up. */
|
|
if (vmbuffer != InvalidBuffer)
|
|
ReleaseBuffer(vmbuffer);
|
|
relation_close(rel, AccessShareLock);
|
|
|
|
/*
|
|
* Before returning, repurpose the fields to match caller's expectations.
|
|
* next is now the next item that should be read (rather than written) and
|
|
* count is now the number of items we wrote (rather than the number we
|
|
* allocated).
|
|
*/
|
|
items->count = items->next;
|
|
items->next = 0;
|
|
|
|
return items;
|
|
}
|
|
|
|
/*
|
|
* Remember one corrupt item.
|
|
*/
|
|
static void
|
|
record_corrupt_item(corrupt_items *items, ItemPointer tid)
|
|
{
|
|
/* enlarge output array if needed. */
|
|
if (items->next >= items->count)
|
|
{
|
|
items->count *= 2;
|
|
items->tids = repalloc(items->tids,
|
|
items->count * sizeof(ItemPointerData));
|
|
}
|
|
/* and add the new item */
|
|
items->tids[items->next++] = *tid;
|
|
}
|
|
|
|
/*
|
|
* Check whether a tuple is all-visible relative to a given OldestXmin value.
|
|
* The buffer should contain the tuple and should be locked and pinned.
|
|
*/
|
|
static bool
|
|
tuple_all_visible(HeapTuple tup, TransactionId OldestXmin, Buffer buffer)
|
|
{
|
|
HTSV_Result state;
|
|
TransactionId xmin;
|
|
|
|
state = HeapTupleSatisfiesVacuum(tup, OldestXmin, buffer);
|
|
if (state != HEAPTUPLE_LIVE)
|
|
return false; /* all-visible implies live */
|
|
|
|
/*
|
|
* Neither lazy_scan_heap nor heap_page_is_all_visible will mark a page
|
|
* all-visible unless every tuple is hinted committed. However, those hint
|
|
* bits could be lost after a crash, so we can't be certain that they'll
|
|
* be set here. So just check the xmin.
|
|
*/
|
|
|
|
xmin = HeapTupleHeaderGetXmin(tup->t_data);
|
|
if (!TransactionIdPrecedes(xmin, OldestXmin))
|
|
return false; /* xmin not old enough for all to see */
|
|
|
|
return true;
|
|
}
|