Line data    Source code

       1             : /*--------------------------------------------------------------------------
       2             :  *
       3             :  * test_ginpostinglist.c
       4             :  *      Test varbyte-encoding in ginpostinglist.c
       5             :  *
       6             :  * Copyright (c) 2019-2024, 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           2 : PG_MODULE_MAGIC;
      21             : 
      22           4 : 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           8 : 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           8 :     elog(NOTICE, "testing with (%u, %d), (%u, %d), max %d bytes",
      50             :          0, 1, blk, off, maxsize);
      51           8 :     ItemPointerSet(&orig_itemptrs[0], 0, 1);
      52           8 :     ItemPointerSet(&orig_itemptrs[1], blk, off);
      53             : 
      54             :     /* Encode, and decode it back */
      55           8 :     pl = ginCompressPostingList(orig_itemptrs, 2, maxsize, &nwritten);
      56           8 :     elog(NOTICE, "encoded %d item pointers to %zu bytes",
      57             :          nwritten, SizeOfGinPostingList(pl));
      58             : 
      59           8 :     if (SizeOfGinPostingList(pl) > maxsize)
      60           0 :         elog(ERROR, "overflow: result was %zu bytes, max %d",
      61             :              SizeOfGinPostingList(pl), maxsize);
      62             : 
      63           8 :     decoded_itemptrs = ginPostingListDecode(pl, &ndecoded);
      64           8 :     if (nwritten != ndecoded)
      65           0 :         elog(NOTICE, "encoded %d itemptrs, %d came back", nwritten, ndecoded);
      66             : 
      67             :     /* Check the result */
      68           8 :     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           8 :     if (ndecoded == 2 &&
      75           6 :         !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             :     }
      82           8 : }
      83             : 
      84             : /*
      85             :  * SQL-callable entry point to perform all tests.
      86             :  */
      87             : Datum
      88           2 : test_ginpostinglist(PG_FUNCTION_ARGS)
      89             : {
      90           2 :     test_itemptr_pair(0, 2, 14);
      91           2 :     test_itemptr_pair(0, MaxHeapTuplesPerPage, 14);
      92           2 :     test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 14);
      93           2 :     test_itemptr_pair(MaxBlockNumber, MaxHeapTuplesPerPage, 16);
      94             : 
      95           2 :     PG_RETURN_VOID();
      96             : }