e79b276621
Normally, if a WHERE clause is implied by the predicate of a partial index, we drop that clause from the set of quals used with the index, since it's redundant to test it if we're scanning that index. However, if it's a hash index (or any !amoptionalkey index), this could result in dropping all available quals for the index's first key, preventing us from generating an indexscan. It's fair to question the practical usefulness of this case. Since hash only supports equality quals, the situation could only arise if the index's predicate is "WHERE indexkey = constant", implying that the index contains only one hash value, which would make hash a really poor choice of index type. However, perhaps there are other !amoptionalkey index AMs out there with which such cases are more plausible. To fix, just don't filter the candidate indexquals this way if the index is !amoptionalkey. That's a bit hokey because it may result in testing quals we didn't need to test, but to do it more accurately we'd have to redundantly identify which candidate quals are actually usable with the index, something we don't know at this early stage of planning. Doesn't seem worth the effort. Reported-by: Sergei Glukhov <s.glukhov@postgrespro.ru> Author: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/e200bf38-6b45-446a-83fd-48617211feff@postgrespro.ru Backpatch-through: 14
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.