Line data    Source code

       1              : /*--------------------------------------------------------------------------
       2              :  *
       3              :  * test_ginpostinglist.c
       4              :  *              Test varbyte-encoding in ginpostinglist.c
       5              :  *
       6              :  * Copyright (c) 2019-2026, PostgreSQL Global Development Group
       7              :  *
       8              :  * IDENTIFICATION
       9              :  *              src/test/modules/test_ginpostinglist/test_ginpostinglist.c
      10              :  *
      11              :  * -------------------------------------------------------------------------
      12              :  */
      13              : #include "postgres.h"
      14              : 
      15              : #include "access/gin_private.h"
      16              : #include "access/ginblock.h"
      17              : #include "access/htup_details.h"
      18              : #include "fmgr.h"
      19              : 
      20            0 : PG_MODULE_MAGIC;
      21              : 
      22            0 : PG_FUNCTION_INFO_V1(test_ginpostinglist);
      23              : 
      24              : /*
      25              :  * Encodes a pair of TIDs, and decodes it back. The first TID is always
      26              :  * (0, 1), the second one is formed from the blk/off arguments. The 'maxsize'
      27              :  * argument is passed to ginCompressPostingList(); it can be used to test the
      28              :  * overflow checks.
      29              :  *
      30              :  * The reason that we test a pair, instead of just a single TID, is that
      31              :  * the GinPostingList stores the first TID as is, and the varbyte-encoding
      32              :  * is only used for the deltas between TIDs. So testing a single TID would
      33              :  * not exercise the varbyte encoding at all.
      34              :  *
      35              :  * This function prints NOTICEs to describe what is tested, and how large the
      36              :  * resulting GinPostingList is. Any incorrect results, e.g. if the encode +
      37              :  * decode round trip doesn't return the original input, are reported as
      38              :  * ERRORs.
      39              :  */
      40              : static void
      41            0 : test_itemptr_pair(BlockNumber blk, OffsetNumber off, int maxsize)
      42              : {
      43            0 :         ItemPointerData orig_itemptrs[2];
      44            0 :         ItemPointer decoded_itemptrs;
      45            0 :         GinPostingList *pl;
      46            0 :         int                     nwritten;
      47            0 :         int                     ndecoded;
      48              : 
      49            0 :         elog(NOTICE, "testing with (%u, %d), (%u, %d), max %d bytes",
      50              :                  0, 1, blk, off, maxsize);
      51            0 :         ItemPointerSet(&orig_itemptrs[0], 0, 1);
      52            0 :         ItemPointerSet(&orig_itemptrs[1], blk, off);
      53              : 
      54              :         /* Encode, and decode it back */
      55            0 :         pl = ginCompressPostingList(orig_itemptrs, 2, maxsize, &nwritten);
      56            0 :         elog(NOTICE, "encoded %d item pointers to %zu bytes",
      57              :                  nwritten, SizeOfGinPostingList(pl));
      58              : 
      59            0 :         if (SizeOfGinPostingList(pl) > maxsize)
      60            0 :                 elog(ERROR, "overflow: result was %zu bytes, max %d",
      61              :                          SizeOfGinPostingList(pl), maxsize);
      62              : 
      63            0 :         decoded_itemptrs = ginPostingListDecode(pl, &ndecoded);
      64            0 :         if (nwritten != ndecoded)
      65            0 :                 elog(NOTICE, "encoded %d itemptrs, %d came back", nwritten, ndecoded);
      66              : 
      67              :         /* Check the result */
      68            0 :         if (!ItemPointerEquals(&orig_itemptrs[0], &decoded_itemptrs[0]))
      69            0 :                 elog(ERROR, "mismatch on first itemptr: (%u, %d) vs (%u, %d)",
      70              :                          0, 1,
      71              :                          ItemPointerGetBlockNumber(&decoded_itemptrs[0]),
      72              :                          ItemPointerGetOffsetNumber(&decoded_itemptrs[0]));
      73              : 
      74            0 :         if (ndecoded == 2 &&
      75            0 :                 !ItemPointerEquals(&orig_itemptrs[0], &decoded_itemptrs[0]))
      76              :         {
      77            0 :                 elog(ERROR, "mismatch on second itemptr: (%u, %d) vs (%u, %d)",
      78              :                          0, 1,
      79              :                          ItemPointerGetBlockNumber(&decoded_itemptrs[0]),
      80              :                          ItemPointerGetOffsetNumber(&decoded_itemptrs[0]));
      81            0 :         }
      82            0 : }
      83              : 
      84              : /*
      85              :  * SQL-callable entry point to perform all tests.
      86              :  */
      87              : Datum
      88            0 : test_ginpostinglist(PG_FUNCTION_ARGS)
      89              : {
      90            0 :         test_itemptr_pair(0, 2, 14);
      91            0 :         test_itemptr_pair(0, MaxHeapTuplesPerPage, 14);
      92            0 :         test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 14);
      93            0 :         test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 16);
      94              : 
      95            0 :         PG_RETURN_VOID();
      96              : }