Jeff, > Does anyone see effective_cache_size make a difference anyway? If so, > in what circumstances?
E_C_S, together with random_page_cost, the table and index sizes, the row estimates and the cpu_* costs, form an equation which estimates the cost of doing various kinds of scans, particularly index scan vs. table scan. If you have an extremely small database (< shared_buffers) or a very large database ( > 50X RAM ), the setting for E_C_S probably doesn't matter, but in the fairly common case where some tables and indexes fit in RAM and some don't, it matters. > In my hands, queries for which effective_cache_size might come into > play (for deciding between seq scan and index scan) are instead > planned as bitmap scans. You have a very unusual workload, or a very small database. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
