Line data    Source code

       1             : /*----------------------------------------------------------------------
       2             :  *
       3             :  * tableamapi.c
       4             :  *      Support routines for API for Postgres table access methods
       5             :  *
       6             :  * Portions Copyright (c) 1996-2023, 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/heapam.h"
      15             : #include "access/htup_details.h"
      16             : #include "access/tableam.h"
      17             : #include "access/xact.h"
      18             : #include "catalog/pg_am.h"
      19             : #include "catalog/pg_proc.h"
      20             : #include "commands/defrem.h"
      21             : #include "miscadmin.h"
      22             : #include "utils/fmgroids.h"
      23             : #include "utils/guc_hooks.h"
      24             : #include "utils/memutils.h"
      25             : #include "utils/syscache.h"
      26             : 
      27             : 
      28             : /*
      29             :  * GetTableAmRoutine
      30             :  *      Call the specified access method handler routine to get its
      31             :  *      TableAmRoutine struct, which will be palloc'd in the caller's
      32             :  *      memory context.
      33             :  */
      34             : const TableAmRoutine *
      35     1507002 : GetTableAmRoutine(Oid amhandler)
      36             : {
      37             :     Datum       datum;
      38             :     const TableAmRoutine *routine;
      39             : 
      40     1507002 :     datum = OidFunctionCall0(amhandler);
      41     1507002 :     routine = (TableAmRoutine *) DatumGetPointer(datum);
      42             : 
      43     1507002 :     if (routine == NULL || !IsA(routine, TableAmRoutine))
      44           0 :         elog(ERROR, "table access method handler %u did not return a TableAmRoutine struct",
      45             :              amhandler);
      46             : 
      47             :     /*
      48             :      * Assert that all required callbacks are present. That makes it a bit
      49             :      * easier to keep AMs up to date, e.g. when forward porting them to a new
      50             :      * major version.
      51             :      */
      52             :     Assert(routine->scan_begin != NULL);
      53             :     Assert(routine->scan_end != NULL);
      54             :     Assert(routine->scan_rescan != NULL);
      55             :     Assert(routine->scan_getnextslot != NULL);
      56             : 
      57             :     Assert(routine->parallelscan_estimate != NULL);
      58             :     Assert(routine->parallelscan_initialize != NULL);
      59             :     Assert(routine->parallelscan_reinitialize != NULL);
      60             : 
      61             :     Assert(routine->index_fetch_begin != NULL);
      62             :     Assert(routine->index_fetch_reset != NULL);
      63             :     Assert(routine->index_fetch_end != NULL);
      64             :     Assert(routine->index_fetch_tuple != NULL);
      65             : 
      66             :     Assert(routine->tuple_fetch_row_version != NULL);
      67             :     Assert(routine->tuple_tid_valid != NULL);
      68             :     Assert(routine->tuple_get_latest_tid != NULL);
      69             :     Assert(routine->tuple_satisfies_snapshot != NULL);
      70             :     Assert(routine->index_delete_tuples != NULL);
      71             : 
      72             :     Assert(routine->tuple_insert != NULL);
      73             : 
      74             :     /*
      75             :      * Could be made optional, but would require throwing error during
      76             :      * parse-analysis.
      77             :      */
      78             :     Assert(routine->tuple_insert_speculative != NULL);
      79             :     Assert(routine->tuple_complete_speculative != NULL);
      80             : 
      81             :     Assert(routine->multi_insert != NULL);
      82             :     Assert(routine->tuple_delete != NULL);
      83             :     Assert(routine->tuple_update != NULL);
      84             :     Assert(routine->tuple_lock != NULL);
      85             : 
      86             :     Assert(routine->relation_set_new_filelocator != NULL);
      87             :     Assert(routine->relation_nontransactional_truncate != NULL);
      88             :     Assert(routine->relation_copy_data != NULL);
      89             :     Assert(routine->relation_copy_for_cluster != NULL);
      90             :     Assert(routine->relation_vacuum != NULL);
      91             :     Assert(routine->scan_analyze_next_block != NULL);
      92             :     Assert(routine->scan_analyze_next_tuple != NULL);
      93             :     Assert(routine->index_build_range_scan != NULL);
      94             :     Assert(routine->index_validate_scan != NULL);
      95             : 
      96             :     Assert(routine->relation_size != NULL);
      97             :     Assert(routine->relation_needs_toast_table != NULL);
      98             : 
      99             :     Assert(routine->relation_estimate_size != NULL);
     100             : 
     101             :     /* optional, but one callback implies presence of the other */
     102             :     Assert((routine->scan_bitmap_next_block == NULL) ==
     103             :            (routine->scan_bitmap_next_tuple == NULL));
     104             :     Assert(routine->scan_sample_next_block != NULL);
     105             :     Assert(routine->scan_sample_next_tuple != NULL);
     106             : 
     107     1507002 :     return routine;
     108             : }
     109             : 
     110             : /* check_hook: validate new default_table_access_method */
     111             : bool
     112        1628 : check_default_table_access_method(char **newval, void **extra, GucSource source)
     113             : {
     114        1628 :     if (**newval == '\0')
     115             :     {
     116           6 :         GUC_check_errdetail("%s cannot be empty.",
     117             :                             "default_table_access_method");
     118           6 :         return false;
     119             :     }
     120             : 
     121        1622 :     if (strlen(*newval) >= NAMEDATALEN)
     122             :     {
     123           0 :         GUC_check_errdetail("%s is too long (maximum %d characters).",
     124             :                             "default_table_access_method", NAMEDATALEN - 1);
     125           0 :         return false;
     126             :     }
     127             : 
     128             :     /*
     129             :      * If we aren't inside a transaction, or not connected to a database, we
     130             :      * cannot do the catalog access necessary to verify the method.  Must
     131             :      * accept the value on faith.
     132             :      */
     133        1622 :     if (IsTransactionState() && MyDatabaseId != InvalidOid)
     134             :     {
     135          56 :         if (!OidIsValid(get_table_am_oid(*newval, true)))
     136             :         {
     137             :             /*
     138             :              * When source == PGC_S_TEST, don't throw a hard error for a
     139             :              * nonexistent table access method, only a NOTICE. See comments in
     140             :              * guc.h.
     141             :              */
     142           6 :             if (source == PGC_S_TEST)
     143             :             {
     144           0 :                 ereport(NOTICE,
     145             :                         (errcode(ERRCODE_UNDEFINED_OBJECT),
     146             :                          errmsg("table access method \"%s\" does not exist",
     147             :                                 *newval)));
     148             :             }
     149             :             else
     150             :             {
     151           6 :                 GUC_check_errdetail("Table access method \"%s\" does not exist.",
     152             :                                     *newval);
     153           6 :                 return false;
     154             :             }
     155             :         }
     156             :     }
     157             : 
     158        1610 :     return true;
     159             : }