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       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                 :           1 : PG_MODULE_MAGIC;
      21                 :             : 
      22                 :           2 : 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                 :           4 : test_itemptr_pair(BlockNumber blk, OffsetNumber off, int maxsize)
      42                 :             : {
      43                 :             :     ItemPointerData orig_itemptrs[2];
      44                 :             :     ItemPointer decoded_itemptrs;
      45                 :             :     GinPostingList *pl;
      46                 :             :     int         nwritten;
      47                 :             :     int         ndecoded;
      48                 :             : 
      49         [ +  - ]:           4 :     elog(NOTICE, "testing with (%u, %d), (%u, %d), max %d bytes",
      50                 :             :          0, 1, blk, off, maxsize);
      51                 :           4 :     ItemPointerSet(&orig_itemptrs[0], 0, 1);
      52                 :           4 :     ItemPointerSet(&orig_itemptrs[1], blk, off);
      53                 :             : 
      54                 :             :     /* Encode, and decode it back */
      55                 :           4 :     pl = ginCompressPostingList(orig_itemptrs, 2, maxsize, &nwritten);
      56         [ +  - ]:           4 :     elog(NOTICE, "encoded %d item pointers to %zu bytes",
      57                 :             :          nwritten, SizeOfGinPostingList(pl));
      58                 :             : 
      59         [ -  + ]:           4 :     if (SizeOfGinPostingList(pl) > maxsize)
      60         [ #  # ]:           0 :         elog(ERROR, "overflow: result was %zu bytes, max %d",
      61                 :             :              SizeOfGinPostingList(pl), maxsize);
      62                 :             : 
      63                 :           4 :     decoded_itemptrs = ginPostingListDecode(pl, &ndecoded);
      64         [ -  + ]:           4 :     if (nwritten != ndecoded)
      65         [ #  # ]:           0 :         elog(NOTICE, "encoded %d itemptrs, %d came back", nwritten, ndecoded);
      66                 :             : 
      67                 :             :     /* Check the result */
      68         [ -  + ]:           4 :     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         [ +  + ]:           4 :     if (ndecoded == 2 &&
      75         [ -  + ]:           3 :         !ItemPointerEquals(&orig_itemptrs[1], &decoded_itemptrs[1]))
      76                 :             :     {
      77         [ #  # ]:           0 :         elog(ERROR, "mismatch on second itemptr: (%u, %d) vs (%u, %d)",
      78                 :             :              blk, off,
      79                 :             :              ItemPointerGetBlockNumber(&decoded_itemptrs[1]),
      80                 :             :              ItemPointerGetOffsetNumber(&decoded_itemptrs[1]));
      81                 :             :     }
      82                 :           4 : }
      83                 :             : 
      84                 :             : /*
      85                 :             :  * SQL-callable entry point to perform all tests.
      86                 :             :  */
      87                 :             : Datum
      88                 :           1 : test_ginpostinglist(PG_FUNCTION_ARGS)
      89                 :             : {
      90                 :           1 :     test_itemptr_pair(0, 2, 14);
      91                 :           1 :     test_itemptr_pair(0, MaxHeapTuplesPerPage, 14);
      92                 :           1 :     test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 14);
      93                 :           1 :     test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 16);
      94                 :             : 
      95                 :           1 :     PG_RETURN_VOID();
      96                 :             : }