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| author | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2017-03-24 14:06:10 -0300 |
|---|---|---|
| committer | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2017-03-24 14:06:10 -0300 |
| commit | 7b504eb282ca2f5104b5c00b4f05a3ef6bb1385b (patch) | |
| tree | 4b12f53c5bd25a03f1016f1daa0809606b47df3a /src/backend/commands/alter.c | |
| parent | f120b614e070aed39586d1443193738a149a90d4 (diff) | |
| download | postgresql-7b504eb282ca2f5104b5c00b4f05a3ef6bb1385b.tar.gz postgresql-7b504eb282ca2f5104b5c00b4f05a3ef6bb1385b.zip | |
Implement multivariate n-distinct coefficients
Add support for explicitly declared statistic objects (CREATE
STATISTICS), allowing collection of statistics on more complex
combinations that individual table columns. Companion commands DROP
STATISTICS and ALTER STATISTICS ... OWNER TO / SET SCHEMA / RENAME are
added too. All this DDL has been designed so that more statistic types
can be added later on, such as multivariate most-common-values and
multivariate histograms between columns of a single table, leaving room
for permitting columns on multiple tables, too, as well as expressions.
This commit only adds support for collection of n-distinct coefficient
on user-specified sets of columns in a single table. This is useful to
estimate number of distinct groups in GROUP BY and DISTINCT clauses;
estimation errors there can cause over-allocation of memory in hashed
aggregates, for instance, so it's a worthwhile problem to solve. A new
special pseudo-type pg_ndistinct is used.
(num-distinct estimation was deemed sufficiently useful by itself that
this is worthwhile even if no further statistic types are added
immediately; so much so that another version of essentially the same
functionality was submitted by Kyotaro Horiguchi:
https://postgr.es/m/20150828.173334.114731693.horiguchi.kyotaro@lab.ntt.co.jp
though this commit does not use that code.)
Author: Tomas Vondra. Some code rework by Álvaro.
Reviewed-by: Dean Rasheed, David Rowley, Kyotaro Horiguchi, Jeff Janes,
Ideriha Takeshi
Discussion: https://postgr.es/m/543AFA15.4080608@fuzzy.cz
https://postgr.es/m/20170320190220.ixlaueanxegqd5gr@alvherre.pgsql
Diffstat (limited to 'src/backend/commands/alter.c')
| -rw-r--r-- | src/backend/commands/alter.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c index cf1391c2e6b..2c6435b7598 100644 --- a/src/backend/commands/alter.c +++ b/src/backend/commands/alter.c @@ -33,6 +33,7 @@ #include "catalog/pg_opfamily.h" #include "catalog/pg_proc.h" #include "catalog/pg_subscription.h" +#include "catalog/pg_statistic_ext.h" #include "catalog/pg_ts_config.h" #include "catalog/pg_ts_dict.h" #include "catalog/pg_ts_parser.h" @@ -120,6 +121,10 @@ report_namespace_conflict(Oid classId, const char *name, Oid nspOid) Assert(OidIsValid(nspOid)); msgfmt = gettext_noop("conversion \"%s\" already exists in schema \"%s\""); break; + case StatisticExtRelationId: + Assert(OidIsValid(nspOid)); + msgfmt = gettext_noop("statistics \"%s\" already exists in schema \"%s\""); + break; case TSParserRelationId: Assert(OidIsValid(nspOid)); msgfmt = gettext_noop("text search parser \"%s\" already exists in schema \"%s\""); @@ -373,6 +378,7 @@ ExecRenameStmt(RenameStmt *stmt) case OBJECT_OPCLASS: case OBJECT_OPFAMILY: case OBJECT_LANGUAGE: + case OBJECT_STATISTIC_EXT: case OBJECT_TSCONFIGURATION: case OBJECT_TSDICTIONARY: case OBJECT_TSPARSER: @@ -489,6 +495,7 @@ ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt, case OBJECT_OPERATOR: case OBJECT_OPCLASS: case OBJECT_OPFAMILY: + case OBJECT_STATISTIC_EXT: case OBJECT_TSCONFIGURATION: case OBJECT_TSDICTIONARY: case OBJECT_TSPARSER: @@ -803,6 +810,7 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt) case OBJECT_OPERATOR: case OBJECT_OPCLASS: case OBJECT_OPFAMILY: + case OBJECT_STATISTIC_EXT: case OBJECT_TABLESPACE: case OBJECT_TSDICTIONARY: case OBJECT_TSCONFIGURATION: |