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Move code specific to pg_ndistinct to new file

Browse Source 
This new file is named pg_ndistinct.c and includes all the code directly
related to the data type pg_ndistinct, extracted from the extended
statistics code.

Some patches are under discussion to change its input and output
functions, and this separation makes the follow-up changes cleaner by
separating the logic related to the data type and the multivariate
ndistinct coefficient core logic in mvdistinct.c.

Author: Corey Huinker <corey.huinker@gmail.com>
Co-authored-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/aQ2k8--a0FfwSwX9@paquier.xyz
This commit is contained in:
Michael Paquier
2025-11-12 16:34:52 +09:00
parent df53fa1c1e
commit a552312343
4 changed files with 104 additions and 85 deletions
Download Patch File Download Diff File Expand all files Collapse all files

85
src/backend/statistics/mvdistinct.c
View File

@@ -27,10 +27,7 @@
#include "catalog/pg_statistic_ext.h"
#include "catalog/pg_statistic_ext_data.h"
#include "lib/stringinfo.h"
#include "statistics/extended_stats_internal.h"
#include "statistics/statistics.h"
#include "utils/fmgrprotos.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
#include "varatt.h"
@@ -328,88 +325,6 @@ statext_ndistinct_deserialize(bytea *data)
return ndistinct;
}
/*
* 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
* 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++)
{
int j;
MVNDistinctItem item = ndist->items[i];
if (i > 0)
appendStringInfoString(&str, ", ");
for (j = 0; j < item.nattributes; j++)
{
AttrNumber attnum = item.attributes[j];
appendStringInfo(&str, "%s%d", (j == 0) ? "\"" : ", ", attnum);
}
appendStringInfo(&str, "\": %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);
}
/*
* ndistinct_for_combination
* Estimates number of distinct values in a combination of columns.

1
src/backend/utils/adt/Makefile
View File

@@ -85,6 +85,7 @@ OBJS = \
pg_locale_icu.o \
pg_locale_libc.o \
pg_lsn.o \
pg_ndistinct.o \
pg_upgrade_support.o \
pgstatfuncs.o \
pseudorandomfuncs.o \

1
src/backend/utils/adt/meson.build
View File

@@ -81,6 +81,7 @@ backend_sources += files(
'pg_locale_icu.c',
'pg_locale_libc.c',
'pg_lsn.c',
'pg_ndistinct.c',
'pg_upgrade_support.c',
'pgstatfuncs.c',
'pseudorandomfuncs.c',

102
src/backend/utils/adt/pg_ndistinct.c Normal file
View File

@@ -0,0 +1,102 @@
/*-------------------------------------------------------------------------
*
* 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 "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
* 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++)
{
int j;
MVNDistinctItem item = ndist->items[i];
if (i > 0)
appendStringInfoString(&str, ", ");
for (j = 0; j < item.nattributes; j++)
{
AttrNumber attnum = item.attributes[j];
appendStringInfo(&str, "%s%d", (j == 0) ? "\"" : ", ", attnum);
}
appendStringInfo(&str, "\": %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);
}