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/*
* Copyright (c) 1996-2024, PostgreSQL Global Development Group
* Copyright (c) 2012, OmniTI Computer Consulting, Inc.
* Portions Copyright (c) 1994, The Regents of the University of California
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* * Neither the name OmniTI Computer Consulting, Inc. nor the names
* of its contributors may be used to endorse or promote products
* derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "postgres.h"
#include "funcapi.h"
#include "access/heapam.h"
#if PG_VERSION_NUM >= 120000
#include "access/table.h"
#include "utils/snapmgr.h"
#else
#include "utils/tqual.h"
#endif
#include "utils/rel.h"
#include "catalog/pg_type.h"
#include "access/tupconvert.h"
#if PG_VERSION_NUM >= 90300
#include "access/htup_details.h"
#endif
#include "access/xlog.h" /* RecoveryInProgress */
#include "miscadmin.h" /* superuser */
#include "storage/procarray.h" /* GetOldestXmin */
#include "dirtyread_tupconvert.h"
typedef struct
{
Relation rel;
TupleDesc reltupdesc;
TupleConversionMap *map;
#if PG_VERSION_NUM >= 120000
TableScanDesc scan;
#else
HeapScanDesc scan;
#endif
OldestXminType oldest_xmin;
} pg_dirtyread_ctx;
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(pg_dirtyread);
PGDLLEXPORT Datum pg_dirtyread(PG_FUNCTION_ARGS);
Datum
pg_dirtyread(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
pg_dirtyread_ctx *usr_ctx;
HeapTuple tuplein;
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;
Oid relid;
TupleDesc tupdesc;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use pg_dirtyread")));
relid = PG_GETARG_OID(0);
if (!OidIsValid(relid))
elog(ERROR, "invalid relation oid \"%d\"", relid);
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
usr_ctx = (pg_dirtyread_ctx *) palloc(sizeof(pg_dirtyread_ctx));
usr_ctx->rel =
#if PG_VERSION_NUM >= 120000
table_open(relid, AccessShareLock);
#else
heap_open(relid, AccessShareLock);
#endif
usr_ctx->reltupdesc = RelationGetDescr(usr_ctx->rel);
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
usr_ctx->map = dirtyread_convert_tuples_by_name(usr_ctx->reltupdesc,
funcctx->tuple_desc, "Error converting tuple descriptors!");
usr_ctx->scan = heap_beginscan(usr_ctx->rel, SnapshotAny, 0, NULL
#if PG_VERSION_NUM >= 120000
, NULL, SO_TYPE_SEQSCAN
#endif
);
#if PG_VERSION_NUM >= 140000
usr_ctx->oldest_xmin = GlobalVisTestFor(usr_ctx->rel);
#else
/* only call GetOldestXmin while not in recovery */
if (!RecoveryInProgress())
usr_ctx->oldest_xmin = GetOldestXmin(
#if PG_VERSION_NUM >= 90400
usr_ctx->rel
#else
false /* allDbs */
#endif
, 0);
#endif
funcctx->user_fctx = (void *) usr_ctx;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
usr_ctx = (pg_dirtyread_ctx *) funcctx->user_fctx;
if ((tuplein = heap_getnext(usr_ctx->scan, ForwardScanDirection)) != NULL)
{
if (usr_ctx->map != NULL)
{
tuplein = dirtyread_do_convert_tuple(tuplein, usr_ctx->map, usr_ctx->oldest_xmin);
SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuplein));
}
else
SRF_RETURN_NEXT(funcctx, heap_copy_tuple_as_datum(tuplein, usr_ctx->reltupdesc));
}
else
{
heap_endscan(usr_ctx->scan);
#if PG_VERSION_NUM >= 120000
table_close(usr_ctx->rel, AccessShareLock);
#else
heap_close(usr_ctx->rel, AccessShareLock);
#endif
SRF_RETURN_DONE(funcctx);
}
}
/* vim:et
*/
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