b3817f5f77
Invent a new flag bit HASH_STRINGS to specify C-string hashing, which was formerly the default; and add assertions insisting that exactly one of the bits HASH_STRINGS, HASH_BLOBS, and HASH_FUNCTION be set. This is in hopes of preventing recurrences of the type of oversight fixed in commit a1b8aa1e4 (i.e., mistakenly omitting HASH_BLOBS). Also, when HASH_STRINGS is specified, insist that the keysize be more than 8 bytes. This is a heuristic, but it should catch accidental use of HASH_STRINGS for integer or pointer keys. (Nearly all existing use-cases set the keysize to NAMEDATALEN or more, so there's little reason to think this restriction should be problematic.) Tweak hash_create() to insist that the HASH_ELEM flag be set, and remove the defaults it had for keysize and entrysize. Since those defaults were undocumented and basically useless, no callers omitted HASH_ELEM anyway. Also, remove memset's zeroing the HASHCTL parameter struct from those callers that had one. This has never been really necessary, and while it wasn't a bad coding convention it was confusing that some callers did it and some did not. We might as well save a few cycles by standardizing on "not". Also improve the documentation for hash_create(). In passing, improve reinit.c's usage of a hash table by storing the key as a binary Oid rather than a string; and, since that's a temporary hash table, allocate it in CurrentMemoryContext for neatness. Discussion: https://postgr.es/m/590625.1607878171@sss.pgh.pa.us
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/.