563a053bdd
~> (cube, int) operator was especially designed for knn-gist search. However, it appears that knn-gist search can't work correctly with current behavior of this operator when dataset contains cubes of variable dimensionality. In this case, the same value of second operator argument can point to different dimension depending on dimensionality of particular cube. Such behavior is incompatible with gist indexing of cubes, and knn-gist doesn't work correctly for it. This patch changes behavior of ~> (cube, int) operator by introducing dimension numbering where value of second argument unambiguously identifies number of dimension. With new behavior, this operator can be correctly supported by knn-gist. Relevant changes to cube operator class are also included. Backpatch to v9.6 where operator was introduced. Since behavior of ~> (cube, int) operator is changed, depending entities must be refreshed after upgrade. Such as, expression indexes using this operator must be reindexed, materialized views must be rebuilt, stored procedures and client code must be revised to correctly use new behavior. That should be mentioned in release notes. Noticed by: Tomas Vondra Author: Alexander Korotkov Reviewed by: Tomas Vondra, Andrey Borodin Discussion: https://www.postgresql.org/message-id/flat/a9657f6a-b497-36ff-e56-482a2c7e3292@2ndquadrant.com
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.