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Provide a facility that (1) can be used to stabilize certain plan choices so that the planner cannot reverse course without authorization and (2) can be used by knowledgeable users to insist on plan choices contrary to what the planner believes best. In both cases, terrible outcomes are possible: users should think twice and perhaps three times before constraining the planner's ability to do as it thinks best; nevertheless, there are problems that are much more easily solved with these facilities than without them. This patch takes the approach of analyzing a finished plan to produce textual output, which we call "plan advice", that describes key decisions made during plan; if that plan advice is provided during future planning cycles, it will force those key decisions to be made in the same way. Not all planner decisions can be controlled using advice; for example, decisions about how to perform aggregation are currently out of scope, as is choice of sort order. Plan advice can also be edited by the user, or even written from scratch in simple cases, making it possible to generate outcomes that the planner would not have produced. Partial advice can be provided to control some planner outcomes but not others. Currently, plan advice is focused only on specific outcomes, such as the choice to use a sequential scan for a particular relation, and not on estimates that might contribute to those outcomes, such as a possibly-incorrect selectivity estimate. While it would be useful to users to be able to provide plan advice that affects selectivity estimates or other aspects of costing, that is out of scope for this commit. Reviewed-by: Lukas Fittl <lukas@fittl.com> Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com> Reviewed-by: Greg Burd <greg@burd.me> Reviewed-by: Jacob Champion <jacob.champion@enterprisedb.com> Reviewed-by: Haibo Yan <tristan.yim@gmail.com> Reviewed-by: Dian Fay <di@nmfay.com> Reviewed-by: Ajay Pal <ajay.pal.k@gmail.com> Reviewed-by: John Naylor <johncnaylorls@gmail.com> Reviewed-by: Alexandra Wang <alexandra.wang.oss@gmail.com> Discussion: http://postgr.es/m/CA+TgmoZ-Jh1T6QyWoCODMVQdhTUPYkaZjWztzP1En4=ZHoKPzw@mail.gmail.com |
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| .. | ||
| amcheck | ||
| auth_delay | ||
| auto_explain | ||
| basebackup_to_shell | ||
| basic_archive | ||
| bloom | ||
| bool_plperl | ||
| btree_gin | ||
| btree_gist | ||
| citext | ||
| cube | ||
| dblink | ||
| dict_int | ||
| dict_xsyn | ||
| earthdistance | ||
| file_fdw | ||
| fuzzystrmatch | ||
| hstore | ||
| hstore_plperl | ||
| hstore_plpython | ||
| intagg | ||
| intarray | ||
| isn | ||
| jsonb_plperl | ||
| jsonb_plpython | ||
| lo | ||
| ltree | ||
| ltree_plpython | ||
| oid2name | ||
| pageinspect | ||
| passwordcheck | ||
| pg_buffercache | ||
| pg_freespacemap | ||
| pg_logicalinspect | ||
| pg_overexplain | ||
| pg_plan_advice | ||
| pg_prewarm | ||
| pg_stat_statements | ||
| pg_surgery | ||
| pg_trgm | ||
| pg_visibility | ||
| pg_walinspect | ||
| pgcrypto | ||
| pgrowlocks | ||
| pgstattuple | ||
| postgres_fdw | ||
| seg | ||
| sepgsql | ||
| spi | ||
| sslinfo | ||
| start-scripts | ||
| tablefunc | ||
| tcn | ||
| test_decoding | ||
| tsm_system_rows | ||
| tsm_system_time | ||
| unaccent | ||
| uuid-ossp | ||
| vacuumlo | ||
| xml2 | ||
| contrib-global.mk | ||
| Makefile | ||
| meson.build | ||
| 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.