From b3817f5f774663d55931dd4fab9c5a94a15ae7ab Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 15 Dec 2020 11:38:53 -0500 Subject: Improve hash_create()'s API for some added robustness. 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 --- src/backend/access/gist/gistbuildbuffers.c | 1 - 1 file changed, 1 deletion(-) (limited to 'src/backend/access/gist/gistbuildbuffers.c') diff --git a/src/backend/access/gist/gistbuildbuffers.c b/src/backend/access/gist/gistbuildbuffers.c index 4ad67c88b4e..217c199a147 100644 --- a/src/backend/access/gist/gistbuildbuffers.c +++ b/src/backend/access/gist/gistbuildbuffers.c @@ -76,7 +76,6 @@ gistInitBuildBuffers(int pagesPerBuffer, int levelStep, int maxLevel) * nodeBuffersTab hash is association between index blocks and it's * buffers. */ - memset(&hashCtl, 0, sizeof(hashCtl)); hashCtl.keysize = sizeof(BlockNumber); hashCtl.entrysize = sizeof(GISTNodeBuffer); hashCtl.hcxt = CurrentMemoryContext; -- cgit v1.2.3