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nodeSubplan.c
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Tom Lane authored
as well as the hash function (formerly the comparison function was hardwired as memcmp()). This makes it possible to eliminate the special-purpose hashtable management code in execGrouping.c in favor of using dynahash to manage tuple hashtables; which is a win because dynahash knows how to expand a hashtable when the original size estimate was too small, whereas the special-purpose code was too stupid to do that. (See recent gripe from Stephan Szabo about poor performance when hash table size estimate is way off.) Free side benefit: when using string_hash, the default comparison function is now strncmp() instead of memcmp(). This should eliminate some part of the overhead associated with larger NAMEDATALEN values.
Tom Lane authoredas well as the hash function (formerly the comparison function was hardwired as memcmp()). This makes it possible to eliminate the special-purpose hashtable management code in execGrouping.c in favor of using dynahash to manage tuple hashtables; which is a win because dynahash knows how to expand a hashtable when the original size estimate was too small, whereas the special-purpose code was too stupid to do that. (See recent gripe from Stephan Szabo about poor performance when hash table size estimate is way off.) Free side benefit: when using string_hash, the default comparison function is now strncmp() instead of memcmp(). This should eliminate some part of the overhead associated with larger NAMEDATALEN values.
