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When building BRIN indexes, the brinbuildCallback only advances to the next page range when seeing a tuple that doesn't belong to the current one. This means that the index may end up missing ranges at the end of the table, if those pages do not contain any indexable tuples. We tend not to have completely empty pages at the end of a relation, but this also applies to partial indexes, where the tuples may simply not match the index predicate. This results in inefficient scans using the affected BRIN index - without the summaries, the page ranges have to be read and processed, which consumes I/O and possibly also CPU time. The existing code already added empty ranges for earlier parts of the table, this commit makes sure we add them for the ranges at the end of the table too. Patch by Matthias van de Meent, with review/improvements by me. Author: Matthias van de Meent Reviewed-by: Tomas Vondra Discussion: https://postgr.es/m/CAEze2WiMsPZg%3DxkvSF_jt4%3D69k6K7gz5B8V2wY3gCGZ%2B1BzCbQ%40mail.gmail.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
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also build and install them all by running "make all" and "make
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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.