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/*-------------------------------------------------------------------------
*
* pg_ndistinct.c
* pg_ndistinct data type support.
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/utils/adt/pg_ndistinct.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "lib/stringinfo.h"
#include "statistics/extended_stats_internal.h"
#include "statistics/statistics_format.h"
#include "utils/fmgrprotos.h"
/*
* pg_ndistinct_in
* input routine for type pg_ndistinct
*
* pg_ndistinct is real enough to be a table column, but it has no
* operations of its own, and disallows input (just like pg_node_tree).
*/
Datum
pg_ndistinct_in(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot accept a value of type %s", "pg_ndistinct")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
/*
* pg_ndistinct_out
* output routine for type pg_ndistinct
*
* Produces a human-readable representation of the value.
*/
Datum
pg_ndistinct_out(PG_FUNCTION_ARGS)
{
bytea *data = PG_GETARG_BYTEA_PP(0);
MVNDistinct *ndist = statext_ndistinct_deserialize(data);
int i;
StringInfoData str;
initStringInfo(&str);
appendStringInfoChar(&str, '[');
for (i = 0; i < ndist->nitems; i++)
{
MVNDistinctItem item = ndist->items[i];
if (i > 0)
appendStringInfoString(&str, ", ");
if (item.nattributes <= 0)
elog(ERROR, "invalid zero-length attribute array in MVNDistinct");
appendStringInfo(&str, "{\"" PG_NDISTINCT_KEY_ATTRIBUTES "\": [%d",
item.attributes[0]);
for (int j = 1; j < item.nattributes; j++)
appendStringInfo(&str, ", %d", item.attributes[j]);
appendStringInfo(&str, "], \"" PG_NDISTINCT_KEY_NDISTINCT "\": %d}",
(int) item.ndistinct);
}
appendStringInfoChar(&str, ']');
PG_RETURN_CSTRING(str.data);
}
/*
* pg_ndistinct_recv
* binary input routine for type pg_ndistinct
*/
Datum
pg_ndistinct_recv(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot accept a value of type %s", "pg_ndistinct")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
/*
* pg_ndistinct_send
* binary output routine for type pg_ndistinct
*
* n-distinct is serialized into a bytea value, so let's send that.
*/
Datum
pg_ndistinct_send(PG_FUNCTION_ARGS)
{
return byteasend(fcinfo);
}
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