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Collect and use multi-column dependency stats

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Follow on patch in the multi-variate statistics patch series.

CREATE STATISTICS s1 WITH (dependencies) ON (a, b) FROM t;
ANALYZE;
will collect dependency stats on (a, b) and then use the measured
dependency in subsequent query planning.

Commit 7b504eb282 added
CREATE STATISTICS with n-distinct coefficients. These are now
specified using the mutually exclusive option WITH (ndistinct).

Author: Tomas Vondra, David Rowley
Reviewed-by: Kyotaro HORIGUCHI, Álvaro Herrera, Dean Rasheed, Robert Haas
and many other comments and contributions
Discussion: https://postgr.es/m/56f40b20-c464-fad2-ff39-06b668fac47c@2ndquadrant.com
This commit is contained in:
Simon Riggs
2017-04-05 18:00:42 -04:00
parent 00b6b6feb1
commit 2686ee1b7c
31 changed files with 2035 additions and 79 deletions
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17
src/backend/commands/statscmds.c
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@@ -62,10 +62,11 @@ CreateStatistics(CreateStatsStmt *stmt)
Oid relid;
ObjectAddress parentobject,
childobject;
Datum types[1]; /* only ndistinct defined now */
Datum types[2]; /* one for each possible type of statistics */
int ntypes;
ArrayType *staenabled;
bool build_ndistinct;
bool build_dependencies;
bool requested_type = false;
Assert(IsA(stmt, CreateStatsStmt));
@@ -159,7 +160,7 @@ CreateStatistics(CreateStatsStmt *stmt)
errmsg("statistics require at least 2 columns")));
/*
* Sort the attnums, which makes detecting duplicies somewhat easier, and
* Sort the attnums, which makes detecting duplicities somewhat easier, and
* it does not hurt (it does not affect the efficiency, unlike for
* indexes, for example).
*/
@@ -182,6 +183,7 @@ CreateStatistics(CreateStatsStmt *stmt)
* recognized.
*/
build_ndistinct = false;
build_dependencies = false;
foreach(l, stmt->options)
{
DefElem *opt = (DefElem *) lfirst(l);
@@ -191,6 +193,11 @@ CreateStatistics(CreateStatsStmt *stmt)
build_ndistinct = defGetBoolean(opt);
requested_type = true;
}
else if (strcmp(opt->defname, "dependencies") == 0)
{
build_dependencies = defGetBoolean(opt);
requested_type = true;
}
else
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
@@ -199,12 +206,17 @@ CreateStatistics(CreateStatsStmt *stmt)
}
/* If no statistic type was specified, build them all. */
if (!requested_type)
{
build_ndistinct = true;
build_dependencies = true;
}
/* construct the char array of enabled statistic types */
ntypes = 0;
if (build_ndistinct)
types[ntypes++] = CharGetDatum(STATS_EXT_NDISTINCT);
if (build_dependencies)
types[ntypes++] = CharGetDatum(STATS_EXT_DEPENDENCIES);
Assert(ntypes > 0);
staenabled = construct_array(types, ntypes, CHAROID, 1, true, 'c');
@@ -222,6 +234,7 @@ CreateStatistics(CreateStatsStmt *stmt)
/* no statistics build yet */
nulls[Anum_pg_statistic_ext_standistinct - 1] = true;
nulls[Anum_pg_statistic_ext_stadependencies - 1] = true;
/* insert it into pg_statistic_ext */
statrel = heap_open(StatisticExtRelationId, RowExclusiveLock);