Line data    Source code

       1             : /*----------------------------------------------------------------------
       2             :  *
       3             :  * tableamapi.c
       4             :  *      Support routines for API for Postgres table access methods
       5             :  *
       6             :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  * src/backend/access/table/tableamapi.c
      10             :  *----------------------------------------------------------------------
      11             :  */
      12             : #include "postgres.h"
      13             : 
      14             : #include "access/tableam.h"
      15             : #include "access/xact.h"
      16             : #include "commands/defrem.h"
      17             : #include "miscadmin.h"
      18             : #include "utils/guc_hooks.h"
      19             : 
      20             : 
      21             : /*
      22             :  * GetTableAmRoutine
      23             :  *      Call the specified access method handler routine to get its
      24             :  *      TableAmRoutine struct, which we expect to be statically allocated.
      25             :  */
      26             : const TableAmRoutine *
      27     2480240 : GetTableAmRoutine(Oid amhandler)
      28             : {
      29             :     Datum       datum;
      30             :     const TableAmRoutine *routine;
      31             : 
      32     2480240 :     datum = OidFunctionCall0(amhandler);
      33     2480240 :     routine = (const TableAmRoutine *) DatumGetPointer(datum);
      34             : 
      35     2480240 :     if (routine == NULL || !IsA(routine, TableAmRoutine))
      36           0 :         elog(ERROR, "table access method handler %u did not return a TableAmRoutine struct",
      37             :              amhandler);
      38             : 
      39             :     /*
      40             :      * Assert that all required callbacks are present. That makes it a bit
      41             :      * easier to keep AMs up to date, e.g. when forward porting them to a new
      42             :      * major version.
      43             :      */
      44             :     Assert(routine->scan_begin != NULL);
      45             :     Assert(routine->scan_end != NULL);
      46             :     Assert(routine->scan_rescan != NULL);
      47             :     Assert(routine->scan_getnextslot != NULL);
      48             : 
      49             :     Assert(routine->parallelscan_estimate != NULL);
      50             :     Assert(routine->parallelscan_initialize != NULL);
      51             :     Assert(routine->parallelscan_reinitialize != NULL);
      52             : 
      53             :     Assert(routine->index_fetch_begin != NULL);
      54             :     Assert(routine->index_fetch_reset != NULL);
      55             :     Assert(routine->index_fetch_end != NULL);
      56             :     Assert(routine->index_fetch_tuple != NULL);
      57             : 
      58             :     Assert(routine->tuple_fetch_row_version != NULL);
      59             :     Assert(routine->tuple_tid_valid != NULL);
      60             :     Assert(routine->tuple_get_latest_tid != NULL);
      61             :     Assert(routine->tuple_satisfies_snapshot != NULL);
      62             :     Assert(routine->index_delete_tuples != NULL);
      63             : 
      64             :     Assert(routine->tuple_insert != NULL);
      65             : 
      66             :     /*
      67             :      * Could be made optional, but would require throwing error during
      68             :      * parse-analysis.
      69             :      */
      70             :     Assert(routine->tuple_insert_speculative != NULL);
      71             :     Assert(routine->tuple_complete_speculative != NULL);
      72             : 
      73             :     Assert(routine->multi_insert != NULL);
      74             :     Assert(routine->tuple_delete != NULL);
      75             :     Assert(routine->tuple_update != NULL);
      76             :     Assert(routine->tuple_lock != NULL);
      77             : 
      78             :     Assert(routine->relation_set_new_filelocator != NULL);
      79             :     Assert(routine->relation_nontransactional_truncate != NULL);
      80             :     Assert(routine->relation_copy_data != NULL);
      81             :     Assert(routine->relation_copy_for_cluster != NULL);
      82             :     Assert(routine->relation_vacuum != NULL);
      83             :     Assert(routine->scan_analyze_next_block != NULL);
      84             :     Assert(routine->scan_analyze_next_tuple != NULL);
      85             :     Assert(routine->index_build_range_scan != NULL);
      86             :     Assert(routine->index_validate_scan != NULL);
      87             : 
      88             :     Assert(routine->relation_size != NULL);
      89             :     Assert(routine->relation_needs_toast_table != NULL);
      90             : 
      91             :     Assert(routine->relation_estimate_size != NULL);
      92             : 
      93             :     Assert(routine->scan_sample_next_block != NULL);
      94             :     Assert(routine->scan_sample_next_tuple != NULL);
      95             : 
      96     2480240 :     return routine;
      97             : }
      98             : 
      99             : /* check_hook: validate new default_table_access_method */
     100             : bool
     101        2482 : check_default_table_access_method(char **newval, void **extra, GucSource source)
     102             : {
     103        2482 :     if (**newval == '\0')
     104             :     {
     105           6 :         GUC_check_errdetail("\"%s\" cannot be empty.",
     106             :                             "default_table_access_method");
     107           6 :         return false;
     108             :     }
     109             : 
     110        2476 :     if (strlen(*newval) >= NAMEDATALEN)
     111             :     {
     112           0 :         GUC_check_errdetail("\"%s\" is too long (maximum %d characters).",
     113             :                             "default_table_access_method", NAMEDATALEN - 1);
     114           0 :         return false;
     115             :     }
     116             : 
     117             :     /*
     118             :      * If we aren't inside a transaction, or not connected to a database, we
     119             :      * cannot do the catalog access necessary to verify the method.  Must
     120             :      * accept the value on faith.
     121             :      */
     122        2476 :     if (IsTransactionState() && MyDatabaseId != InvalidOid)
     123             :     {
     124         134 :         if (!OidIsValid(get_table_am_oid(*newval, true)))
     125             :         {
     126             :             /*
     127             :              * When source == PGC_S_TEST, don't throw a hard error for a
     128             :              * nonexistent table access method, only a NOTICE. See comments in
     129             :              * guc.h.
     130             :              */
     131           6 :             if (source == PGC_S_TEST)
     132             :             {
     133           0 :                 ereport(NOTICE,
     134             :                         (errcode(ERRCODE_UNDEFINED_OBJECT),
     135             :                          errmsg("table access method \"%s\" does not exist",
     136             :                                 *newval)));
     137             :             }
     138             :             else
     139             :             {
     140           6 :                 GUC_check_errdetail("Table access method \"%s\" does not exist.",
     141             :                                     *newval);
     142           6 :                 return false;
     143             :             }
     144             :         }
     145             :     }
     146             : 
     147        2464 :     return true;
     148             : }