…selective WHERE clause on an indexed column The SQL used for this test together with its …responsible for choosing the join algorithm for a particular query and QEP is not advanced enough and there…”join_cache_level”. For example in my test I forced the optimizer to use hash join by setting join_…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…some respect and what works well for Oracle,MS SQL, PostgreSQL may not work well for MySQL and other… advanced join methods at this point (the work is on a way) – MySQL can’t do hash join or sort merge join -…saw my 30mil rows (12GB) table was scanned in less than 5 minutes. Now if we would do eq join…
Post: Advanced index analysis with mk-index-usage
November 11, 2010 By 2 Comments
… with SQL. I logged all queries to the blog for a little while, and then secure-copied the query log to my… usage on the remote server, and store the results in my MySQL sandbox instance. The new option is –save-results-database…_cnt * 100 AS pct FROM index_usage AS iu INNER JOIN ( SELECT query_id, db, tbl, SUM(cnt) AS total_cnt…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…t use GUIDs. Which brings me to my next point: Use InnoDB Assuming that … so ETL jobs written to rely on SQL tend to get really bogged down. … to think of things that seem “less advanced” than using a database. Sharding and … The nested-loop joins are not all that fast on big joins; the query …
