Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * tablesample.c
       4             :  *        Support functions for TABLESAMPLE feature
       5             :  *
       6             :  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *        src/backend/access/tablesample/tablesample.c
      12             :  *
      13             :  * -------------------------------------------------------------------------
      14             :  */
      15             : 
      16             : #include "postgres.h"
      17             : 
      18             : #include "access/tsmapi.h"
      19             : 
      20             : 
      21             : /*
      22             :  * GetTsmRoutine --- get a TsmRoutine struct by invoking the handler.
      23             :  *
      24             :  * This is a convenience routine that's just meant to check for errors.
      25             :  */
      26             : TsmRoutine *
      27         143 : GetTsmRoutine(Oid tsmhandler)
      28             : {
      29             :     Datum       datum;
      30             :     TsmRoutine *routine;
      31             : 
      32         143 :     datum = OidFunctionCall1(tsmhandler, PointerGetDatum(NULL));
      33         143 :     routine = (TsmRoutine *) DatumGetPointer(datum);
      34             : 
      35         143 :     if (routine == NULL || !IsA(routine, TsmRoutine))
      36           0 :         elog(ERROR, "tablesample handler function %u did not return a TsmRoutine struct",
      37             :              tsmhandler);
      38             : 
      39         143 :     return routine;
      40             : }