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pg_dump: prepare attribute stats query.

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Follow precedent in pg_dump for preparing queries to improve
performance. Also, simplify the query by removing unnecessary joins.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Andres Freund <andres@anarazel.de>
Co-authored-by: Corey Huinker <corey.huinker@gmail.com>
Co-authored-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://postgr.es/m/CADkLM=dRMC6t8gp9GVf6y6E_r5EChQjMAAh_vPyih_zMiq0zvA@mail.gmail.com
This commit is contained in:
Jeff Davis
2025-02-25 19:50:50 -08:00
parent 8f427187db
commit 6ee3b91bad
2 changed files with 58 additions and 66 deletions
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1
src/bin/pg_dump/pg_backup.h
View File

@ -72,6 +72,7 @@ enum _dumpPreparedQueries
PREPQUERY_DUMPOPR,
PREPQUERY_DUMPRANGETYPE,
PREPQUERY_DUMPTABLEATTACH,
PREPQUERY_GETATTRIBUTESTATS,
PREPQUERY_GETCOLUMNACLS,
PREPQUERY_GETDOMAINCONSTRAINTS,
};

123
src/bin/pg_dump/pg_dump.c
View File

@ -10415,10 +10415,8 @@ dumpComment(Archive *fout, const char *type,
* param_name, param_type
*/
static const char *att_stats_arginfo[][2] = {
{"relation", "regclass"},
{"attname", "name"},
{"inherited", "boolean"},
{"version", "integer"},
{"null_frac", "float4"},
{"avg_width", "integer"},
{"n_distinct", "float4"},
@ -10434,60 +10432,6 @@ static const char *att_stats_arginfo[][2] = {
{"range_bounds_histogram", "text"},
};
/*
* getAttStatsExportQuery --
*
* Generate a query that will fetch all attribute (e.g. pg_statistic)
* stats for a given relation.
*/
static void
getAttStatsExportQuery(PQExpBuffer query, Archive *fout,
const char *schemaname, const char *relname)
{
resetPQExpBuffer(query);
appendPQExpBuffer(query,
"SELECT c.oid::regclass AS relation, "
"s.attname,"
"s.inherited,"
"'%u'::integer AS version, "
"s.null_frac,"
"s.avg_width,"
"s.n_distinct,"
"s.most_common_vals,"
"s.most_common_freqs,"
"s.histogram_bounds,"
"s.correlation,"
"s.most_common_elems,"
"s.most_common_elem_freqs,"
"s.elem_count_histogram,",
fout->remoteVersion);
if (fout->remoteVersion >= 170000)
appendPQExpBufferStr(query,
"s.range_length_histogram,"
"s.range_empty_frac,"
"s.range_bounds_histogram ");
else
appendPQExpBufferStr(query,
"NULL AS range_length_histogram,"
"NULL AS range_empty_frac,"
"NULL AS range_bounds_histogram ");
appendPQExpBufferStr(query,
"FROM pg_stats s "
"JOIN pg_namespace n "
"ON n.nspname = s.schemaname "
"JOIN pg_class c "
"ON c.relname = s.tablename "
"AND c.relnamespace = n.oid "
"WHERE s.schemaname = ");
appendStringLiteralAH(query, schemaname, fout);
appendPQExpBufferStr(query, " AND s.tablename = ");
appendStringLiteralAH(query, relname, fout);
appendPQExpBufferStr(query, " ORDER BY s.attname, s.inherited");
}
/*
* appendNamedArgument --
*
@ -10513,17 +10457,17 @@ appendNamedArgument(PQExpBuffer out, Archive *fout, const char *argname,
* Append a formatted pg_restore_relation_stats statement.
*/
static void
appendRelStatsImport(PQExpBuffer out, Archive *fout, const RelStatsInfo *rsinfo)
appendRelStatsImport(PQExpBuffer out, Archive *fout, const RelStatsInfo *rsinfo,
const char *qualified_name)
{
const char *qualname = fmtQualifiedId(rsinfo->dobj.namespace->dobj.name, rsinfo->dobj.name);
char reltuples_str[FLOAT_SHORTEST_DECIMAL_LEN];
float_to_shortest_decimal_buf(rsinfo->reltuples, reltuples_str);
appendPQExpBufferStr(out, "SELECT * FROM pg_catalog.pg_restore_relation_stats(\n");
appendPQExpBuffer(out, "\t'relation', '%s'::regclass,\n", qualname);
appendPQExpBuffer(out, "\t'version', '%u'::integer,\n",
fout->remoteVersion);
appendPQExpBuffer(out, "\t'relation', '%s'::regclass,\n", qualified_name);
appendPQExpBuffer(out, "\t'relpages', '%d'::integer,\n", rsinfo->relpages);
appendPQExpBuffer(out, "\t'reltuples', '%s'::real,\n", reltuples_str);
appendPQExpBuffer(out, "\t'relallvisible', '%d'::integer\n);\n",
@ -10536,13 +10480,18 @@ appendRelStatsImport(PQExpBuffer out, Archive *fout, const RelStatsInfo *rsinfo)
* Append a series of formatted pg_restore_attribute_stats statements.
*/
static void
appendAttStatsImport(PQExpBuffer out, Archive *fout, PGresult *res)
appendAttStatsImport(PQExpBuffer out, Archive *fout, PGresult *res,
const char *qualified_name)
{
for (int rownum = 0; rownum < PQntuples(res); rownum++)
{
const char *sep = "";
appendPQExpBufferStr(out, "SELECT * FROM pg_catalog.pg_restore_attribute_stats(\n");
appendPQExpBuffer(out, "\t'version', '%u'::integer,\n",
fout->remoteVersion);
appendPQExpBuffer(out, "\t'relation', '%s'::regclass,\n",
qualified_name);
for (int argno = 0; argno < lengthof(att_stats_arginfo); argno++)
{
const char *argname = att_stats_arginfo[argno][0];
@ -10607,6 +10556,7 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
DumpableObject *dobj = (DumpableObject *) &rsinfo->dobj;
DumpId *deps = NULL;
int ndeps = 0;
const char *qualified_name;
/* nothing to do if we are not dumping statistics */
if (!fout->dopt->dumpStatistics)
@ -10622,15 +10572,56 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
tag = createPQExpBuffer();
appendPQExpBufferStr(tag, fmtId(dobj->name));
query = createPQExpBuffer();
if (!fout->is_prepared[PREPQUERY_GETATTRIBUTESTATS])
{
appendPQExpBufferStr(query,
"PREPARE getAttributeStats(pg_catalog.name, pg_catalog.name) AS\n"
"SELECT s.attname, s.inherited, "
"s.null_frac, s.avg_width, s.n_distinct, "
"s.most_common_vals, s.most_common_freqs, "
"s.histogram_bounds, s.correlation, "
"s.most_common_elems, s.most_common_elem_freqs, "
"s.elem_count_histogram, ");
if (fout->remoteVersion >= 170000)
appendPQExpBufferStr(query,
"s.range_length_histogram, s.range_empty_frac, "
"s.range_bounds_histogram ");
else
appendPQExpBufferStr(query,
"NULL AS range_length_histogram,"
"NULL AS range_empty_frac,"
"NULL AS range_bounds_histogram ");
appendPQExpBufferStr(query,
"FROM pg_stats s "
"WHERE s.schemaname = $1 "
"AND s.tablename = $2 "
"ORDER BY s.attname, s.inherited");
ExecuteSqlStatement(fout, query->data);
fout->is_prepared[PREPQUERY_GETATTRIBUTESTATS] = true;
resetPQExpBuffer(query);
}
appendPQExpBufferStr(query, "EXECUTE getAttributeStats(");
appendStringLiteralAH(query, dobj->namespace->dobj.name, fout);
appendPQExpBufferStr(query, ", ");
appendStringLiteralAH(query, dobj->name, fout);
appendPQExpBufferStr(query, "); ");
res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
out = createPQExpBuffer();
appendRelStatsImport(out, fout, rsinfo);
qualified_name = fmtQualifiedId(rsinfo->dobj.namespace->dobj.name,
rsinfo->dobj.name);
appendRelStatsImport(out, fout, rsinfo, qualified_name);
appendAttStatsImport(out, fout, res, qualified_name);
query = createPQExpBuffer();
getAttStatsExportQuery(query, fout, dobj->namespace->dobj.name,
dobj->name);
res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
appendAttStatsImport(out, fout, res);
PQclear(res);
ArchiveEntry(fout, nilCatalogId, createDumpId(),