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/*----------------------------------------------------------------------
*
* tableamapi.c
* Support routines for API for Postgres table access methods
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/backend/access/table/tableamapi.c
*----------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "catalog/pg_am.h"
#include "catalog/pg_proc.h"
#include "commands/defrem.h"
#include "miscadmin.h"
#include "utils/fmgroids.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
/*
* GetTableAmRoutine
* Call the specified access method handler routine to get its
* TableAmRoutine struct, which will be palloc'd in the caller's
* memory context.
*/
const TableAmRoutine *
GetTableAmRoutine(Oid amhandler)
{
Datum datum;
const TableAmRoutine *routine;
datum = OidFunctionCall0(amhandler);
routine = (TableAmRoutine *) DatumGetPointer(datum);
if (routine == NULL || !IsA(routine, TableAmRoutine))
elog(ERROR, "table access method handler %u did not return a TableAmRoutine struct",
amhandler);
/*
* Assert that all required callbacks are present. That makes it a bit
* easier to keep AMs up to date, e.g. when forward porting them to a new
* major version.
*/
Assert(routine->scan_begin != NULL);
Assert(routine->scan_end != NULL);
Assert(routine->scan_rescan != NULL);
Assert(routine->scan_getnextslot != NULL);
Assert(routine->parallelscan_estimate != NULL);
Assert(routine->parallelscan_initialize != NULL);
Assert(routine->parallelscan_reinitialize != NULL);
Assert(routine->index_fetch_begin != NULL);
Assert(routine->index_fetch_reset != NULL);
Assert(routine->index_fetch_end != NULL);
Assert(routine->index_fetch_tuple != NULL);
Assert(routine->tuple_fetch_row_version != NULL);
Assert(routine->tuple_tid_valid != NULL);
Assert(routine->tuple_get_latest_tid != NULL);
Assert(routine->tuple_satisfies_snapshot != NULL);
Assert(routine->compute_xid_horizon_for_tuples != NULL);
Assert(routine->tuple_insert != NULL);
/*
* Could be made optional, but would require throwing error during
* parse-analysis.
*/
Assert(routine->tuple_insert_speculative != NULL);
Assert(routine->tuple_complete_speculative != NULL);
Assert(routine->multi_insert != NULL);
Assert(routine->tuple_delete != NULL);
Assert(routine->tuple_update != NULL);
Assert(routine->tuple_lock != NULL);
Assert(routine->relation_set_new_filenode != NULL);
Assert(routine->relation_nontransactional_truncate != NULL);
Assert(routine->relation_copy_data != NULL);
Assert(routine->relation_copy_for_cluster != NULL);
Assert(routine->relation_vacuum != NULL);
Assert(routine->scan_analyze_next_block != NULL);
Assert(routine->scan_analyze_next_tuple != NULL);
Assert(routine->index_build_range_scan != NULL);
Assert(routine->index_validate_scan != NULL);
Assert(routine->relation_size != NULL);
Assert(routine->relation_needs_toast_table != NULL);
Assert(routine->relation_estimate_size != NULL);
/* optional, but one callback implies presence of the other */
Assert((routine->scan_bitmap_next_block == NULL) ==
(routine->scan_bitmap_next_tuple == NULL));
Assert(routine->scan_sample_next_block != NULL);
Assert(routine->scan_sample_next_tuple != NULL);
return routine;
}
/* check_hook: validate new default_table_access_method */
bool
check_default_table_access_method(char **newval, void **extra, GucSource source)
{
if (**newval == '\0')
{
GUC_check_errdetail("%s cannot be empty.",
"default_table_access_method");
return false;
}
if (strlen(*newval) >= NAMEDATALEN)
{
GUC_check_errdetail("%s is too long (maximum %d characters).",
"default_table_access_method", NAMEDATALEN - 1);
return false;
}
/*
* If we aren't inside a transaction, or not connected to a database, we
* cannot do the catalog access necessary to verify the method. Must
* accept the value on faith.
*/
if (IsTransactionState() && MyDatabaseId != InvalidOid)
{
if (!OidIsValid(get_table_am_oid(*newval, true)))
{
/*
* When source == PGC_S_TEST, don't throw a hard error for a
* nonexistent table access method, only a NOTICE. See comments in
* guc.h.
*/
if (source == PGC_S_TEST)
{
ereport(NOTICE,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("table access method \"%s\" does not exist",
*newval)));
}
else
{
GUC_check_errdetail("Table access method \"%s\" does not exist.",
*newval);
return false;
}
}
}
return true;
}
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