Jelte Fennema-Nio <postg...@jeltef.nl> writes: > Running "\d tablename" from psql could take multiple seconds when > running on a system with 100k+ tables. The reason for this was that > a sequence scan on pg_class takes place, due to regex matching being > used.
> Regex matching is obviously unnecessary when we're looking for an exact > match. This checks for this (common) case and starts using plain > equality in that case. Really? ISTM this argument is ignoring an optimization the backend has understood for a long time. regression=# explain select * from pg_class where relname ~ '^foo$'; QUERY PLAN -------------------------------------------------------------------------------- ------------- Index Scan using pg_class_relname_nsp_index on pg_class (cost=0.28..8.30 rows= 1 width=739) Index Cond: (relname = 'foo'::text) Filter: (relname ~ '^foo$'::text) (3 rows) regards, tom lane