postgresql/contrib
Tom Lane 044c99bc56 Use query collation, not column's collation, while examining statistics.
Commit 5e0928005 changed the planner so that, instead of blindly using
DEFAULT_COLLATION_OID when invoking operators for selectivity estimation,
it would use the collation of the column whose statistics we're
considering.  This was recognized as still being not quite the right
thing, but it seemed like a good incremental improvement.  However,
shortly thereafter we introduced nondeterministic collations, and that
creates cases where operators can fail if they're passed the wrong
collation.  We don't want planning to fail in cases where the query itself
would work, so this means that we *must* use the query's collation when
invoking operators for estimation purposes.

The only real problem this creates is in ineq_histogram_selectivity, where
the binary search might produce a garbage answer if we perform comparisons
using a different collation than the column's histogram is ordered with.
However, when the query's collation is significantly different from the
column's default collation, the estimate we previously generated would be
pretty irrelevant anyway; so it's not clear that this will result in
noticeably worse estimates in practice.  (A follow-on patch will improve
this situation in HEAD, but it seems too invasive for back-patch.)

The patch requires changing the signatures of mcv_selectivity and allied
functions, which are exported and very possibly are used by extensions.
In HEAD, I just did that, but an API/ABI break of this sort isn't
acceptable in stable branches.  Therefore, in v12 the patch introduces
"mcv_selectivity_ext" and so on, with signatures matching HEAD, and makes
the old functions into wrappers that assume DEFAULT_COLLATION_OID should
be used.  That does not match the prior behavior, but it should avoid risk
of failure in most cases.  (In practice, I think most extension datatypes
aren't collation-aware, so the change probably doesn't matter to them.)

Per report from James Lucas.  Back-patch to v12 where the problem was
introduced.

Discussion: https://postgr.es/m/CAAFmbbOvfi=wMM=3qRsPunBSLb8BFREno2oOzSBS=mzfLPKABw@mail.gmail.com
2020-06-05 16:18:50 -04:00
..
adminpack Initial pgindent and pgperltidy run for v13. 2020-05-14 13:06:50 -04:00
amcheck Fix amcheck for page checks concurrent to replay of btree page deletion 2020-05-14 12:44:44 +03:00
auth_delay Update copyrights for 2020 2020-01-01 12:21:45 -05:00
auto_explain Add the option to report WAL usage in EXPLAIN and auto_explain. 2020-04-06 08:02:15 +05:30
bloom Implement operator class parameters 2020-03-30 19:17:23 +03:00
bool_plperl Create contrib/bool_plperl to provide a bool transform for PL/Perl[U]. 2020-03-06 17:11:23 -05:00
btree_gin Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
btree_gist Get rid of trailing semicolons in C macro definitions. 2020-05-01 17:28:00 -04:00
citext Move src/backend/utils/hash/hashfn.c to src/common 2020-02-27 09:25:41 +05:30
cube Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
dblink Initialize dblink remoteConn struct in all cases 2020-05-28 13:44:54 -04:00
dict_int Preserve integer and float values accurately in (de)serialize_deflist. 2020-03-10 12:30:02 -04:00
dict_xsyn Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
earthdistance Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
file_fdw Remove utils/acl.h from catalog/objectaddress.h 2020-03-10 10:27:00 +01:00
fuzzystrmatch Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
hstore Improve selectivity estimation for assorted match-style operators. 2020-04-01 10:32:33 -04:00
hstore_plperl Mark some contrib modules as "trusted". 2020-02-13 15:02:35 -05:00
hstore_plpython Split all OBJS style lines in makefiles into one-line-per-entry style. 2019-11-05 14:41:07 -08:00
intagg Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
intarray Initial pgindent and pgperltidy run for v13. 2020-05-14 13:06:50 -04:00
isn Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
jsonb_plperl Mark some contrib modules as "trusted". 2020-02-13 15:02:35 -05:00
jsonb_plpython In jsonb_plpython.c, suppress warning message from gcc 10. 2020-01-30 18:26:12 -05:00
lo Fix bogus CALLED_AS_TRIGGER() defenses. 2020-04-03 11:24:56 -04:00
ltree Use query collation, not column's collation, while examining statistics. 2020-06-05 16:18:50 -04:00
ltree_plpython Improve error messages in ltree_in and lquery_in. 2020-03-31 11:14:42 -04:00
oid2name Add PostgreSQL home page to --help output 2020-02-28 13:12:21 +01:00
pageinspect Remove useless pfree()s at the ends of various ValuePerCall SRFs. 2020-03-16 21:36:53 -04:00
passwordcheck Update copyrights for 2020 2020-01-01 12:21:45 -05:00
pg_buffercache Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
pg_freespacemap Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
pg_prewarm Remove excess parens in ereport() calls 2020-01-30 13:32:04 -03:00
pg_standby pg_standby: Don't use HAVE_WORKING_LINK 2020-03-03 08:54:44 +01:00
pg_stat_statements Initial pgindent and pgperltidy run for v13. 2020-05-14 13:06:50 -04:00
pg_trgm Get rid of trailing semicolons in C macro definitions. 2020-05-01 17:28:00 -04:00
pg_visibility Initial pgindent and pgperltidy run for v13. 2020-05-14 13:06:50 -04:00
pgcrypto Clear some style deviations. 2020-05-21 08:31:16 -07:00
pgrowlocks Avoid holding a directory FD open across assorted SRF calls. 2020-03-16 21:05:52 -04:00
pgstattuple Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
postgres_fdw Use CP_SMALL_TLIST for hash aggregate 2020-05-31 14:43:13 +02:00
seg Use perl warnings pragma consistently 2020-04-13 11:55:45 -04:00
sepgsql Fix cache reference leak in contrib/sepgsql. 2020-04-16 14:45:54 -04:00
spi Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
sslinfo Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
start-scripts Remove contrib/start-scripts/osx/. 2017-11-17 12:53:20 -05:00
tablefunc Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
tcn Mark some contrib modules as "trusted". 2020-02-13 15:02:35 -05:00
test_decoding Propagate ALTER TABLE ... SET STORAGE to indexes 2020-05-08 08:39:17 +02:00
tsm_system_rows Mark some contrib modules as "trusted". 2020-02-13 15:02:35 -05:00
tsm_system_time Mark some contrib modules as "trusted". 2020-02-13 15:02:35 -05:00
unaccent Update Unicode data to Unicode 13.0.0 and CLDR 37 2020-04-24 09:52:59 +02:00
uuid-ossp Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
vacuumlo Add PostgreSQL home page to --help output 2020-02-28 13:12:21 +01:00
xml2 Remove support for upgrading extensions from "unpackaged" state. 2020-02-19 16:59:14 -05:00
Makefile Create contrib/bool_plperl to provide a bool transform for PL/Perl[U]. 2020-03-06 17:11:23 -05:00
README Rename 'gmake' to 'make' in docs and recommended commands 2014-02-12 17:29:19 -05:00
contrib-global.mk Respect TEMP_CONFIG when pg_regress_check and friends are called 2016-02-27 12:28:21 -05:00

README

The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.