mirror of
https://git.postgresql.org/git/postgresql.git
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351 lines
8.9 KiB
C
351 lines
8.9 KiB
C
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/*-------------------------------------------------------------------------
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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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* 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 "funcapi.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.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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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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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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/*
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* Visibility map information for a single block of a relation.
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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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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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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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* 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
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* the 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;
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Page page;
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buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
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bstrategy);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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page = BufferGetPage(buffer);
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if (PageIsAllVisible(page))
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info->bits[blkno] |= (1 << 2);
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UnlockReleaseBuffer(buffer);
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}
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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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return info;
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}
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