1d9351a87c
perform_pruning_combine_step() was not taught about the number of partition indexes used in hash partitioning; more embarrassingly, get_matching_hash_bounds() also had it wrong. These errors are masked in the common case where all the partitions have the same modulus and no partition is missing. However, with missing or unequal-size partitions, we could erroneously prune some partitions that need to be scanned, leading to silently wrong query answers. While a minimal-footprint fix for this could be to export get_partition_bound_num_indexes and make the incorrect functions use it, I'm of the opinion that that function should never have existed in the first place. It's not reasonable data structure design that PartitionBoundInfoData lacks any explicit record of the length of its indexes[] array. Perhaps that was all right when it could always be assumed equal to ndatums, but something should have been done about it as soon as that stopped being true. Putting in an explicit "nindexes" field makes both partition_bounds_equal() and partition_bounds_copy() simpler, safer, and faster than before, and removes explicit knowledge of the number-of-partition-indexes rules from some other places too. This change also makes get_hash_partition_greatest_modulus obsolete. I left that in place in case any external code uses it, but no core code does anymore. Per bug #16840 from Michał Albrycht. Back-patch to v11 where the hash partitioning code came in. (In the back branches, add the new field at the end of PartitionBoundInfoData to minimize ABI risks.) Discussion: https://postgr.es/m/16840-571a22976f829ad4@postgresql.org |
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README
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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.