Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * pg_ndistinct.c
       4             :  *      pg_ndistinct data type support.
       5             :  *
       6             :  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  * IDENTIFICATION
      10             :  *    src/backend/utils/adt/pg_ndistinct.c
      11             :  *
      12             :  *-------------------------------------------------------------------------
      13             :  */
      14             : 
      15             : #include "postgres.h"
      16             : 
      17             : #include "lib/stringinfo.h"
      18             : #include "statistics/extended_stats_internal.h"
      19             : #include "utils/fmgrprotos.h"
      20             : 
      21             : 
      22             : /*
      23             :  * pg_ndistinct_in
      24             :  *      input routine for type pg_ndistinct
      25             :  *
      26             :  * pg_ndistinct is real enough to be a table column, but it has no
      27             :  * operations of its own, and disallows input (just like pg_node_tree).
      28             :  */
      29             : Datum
      30           0 : pg_ndistinct_in(PG_FUNCTION_ARGS)
      31             : {
      32           0 :     ereport(ERROR,
      33             :             (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
      34             :              errmsg("cannot accept a value of type %s", "pg_ndistinct")));
      35             : 
      36             :     PG_RETURN_VOID();           /* keep compiler quiet */
      37             : }
      38             : 
      39             : /*
      40             :  * pg_ndistinct_out
      41             :  *      output routine for type pg_ndistinct
      42             :  *
      43             :  * Produces a human-readable representation of the value.
      44             :  */
      45             : Datum
      46          24 : pg_ndistinct_out(PG_FUNCTION_ARGS)
      47             : {
      48          24 :     bytea      *data = PG_GETARG_BYTEA_PP(0);
      49          24 :     MVNDistinct *ndist = statext_ndistinct_deserialize(data);
      50             :     int         i;
      51             :     StringInfoData str;
      52             : 
      53          24 :     initStringInfo(&str);
      54          24 :     appendStringInfoChar(&str, '{');
      55             : 
      56         120 :     for (i = 0; i < ndist->nitems; i++)
      57             :     {
      58             :         int         j;
      59          96 :         MVNDistinctItem item = ndist->items[i];
      60             : 
      61          96 :         if (i > 0)
      62          72 :             appendStringInfoString(&str, ", ");
      63             : 
      64         312 :         for (j = 0; j < item.nattributes; j++)
      65             :         {
      66         216 :             AttrNumber  attnum = item.attributes[j];
      67             : 
      68         216 :             appendStringInfo(&str, "%s%d", (j == 0) ? "\"" : ", ", attnum);
      69             :         }
      70          96 :         appendStringInfo(&str, "\": %d", (int) item.ndistinct);
      71             :     }
      72             : 
      73          24 :     appendStringInfoChar(&str, '}');
      74             : 
      75          24 :     PG_RETURN_CSTRING(str.data);
      76             : }
      77             : 
      78             : /*
      79             :  * pg_ndistinct_recv
      80             :  *      binary input routine for type pg_ndistinct
      81             :  */
      82             : Datum
      83           0 : pg_ndistinct_recv(PG_FUNCTION_ARGS)
      84             : {
      85           0 :     ereport(ERROR,
      86             :             (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
      87             :              errmsg("cannot accept a value of type %s", "pg_ndistinct")));
      88             : 
      89             :     PG_RETURN_VOID();           /* keep compiler quiet */
      90             : }
      91             : 
      92             : /*
      93             :  * pg_ndistinct_send
      94             :  *      binary output routine for type pg_ndistinct
      95             :  *
      96             :  * n-distinct is serialized into a bytea value, so let's send that.
      97             :  */
      98             : Datum
      99           0 : pg_ndistinct_send(PG_FUNCTION_ARGS)
     100             : {
     101           0 :     return byteasend(fcinfo);
     102             : }