… own, that’s not really a limitation.(Edit: I’m wrong! You can. See …1 ‘TRX HAS BEEN WAITING’ Now in your mysql session, set /tmp/lock_waits as …Bookmark lookup | +- Table | | table actor | | possible_keys PRIMARY | +- Unique index lookup | key actor->PRIMARY | possible_keys PRIMARY | key_len 2 | ref …
Post: MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
…possible_keys | key | key_len | ref | rows | Extra | +—-+————-+———-+——-+—————+—————+———+——+———+———————————————–+ | 1 | SIMPLE | lineitem | range | li_shp_dt_idx | li_shp_dt_idx | 3 | NULL | 8272067 | Using index…
Post: Beware of MySQL Data Truncation
February 7, 2009 By 4 Comments
…mysql> explain select count(*) from article_comment where article_id=4300000000; +—-+————-+—————–+——+—————+————+———+——-+——+————————–+ | id | select_type | table | type | possible_keys | key | key…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…not different selectivity might show benefit from using indexes. In fact even MySQL optimizer currently does not take it into account. For In memory workload index…wrong. Do not take me as going against normalization or joins. It is great principle and should be used when possible. Just do not…
Post: MySQL Crash Recovery
July 30, 2006 By 30 Comments
…and do not expose itself instantly – you may notice wrong query … as possible. This hack is needed only in some cases – in …not be basing my failure handling scenarios. Cold Start – If you restart MySQL server its caches (key…- Unlike MyISAM Innodb does not store index cardinality in tables, instead it…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
…MySQL‘s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key…possibility of having multiple key caches. But I’ll give the simple version here. In my opinion, you should choose a key…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
…possible_keys: d key: d key_len: 7 ref: NULL rows: 3681 Extra: Using where 1 row in set (0.01 sec) mysql…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
…not serializable. PZ: Cool. This is one of little known new features in MySQL…in 5.1.x? Is it possible…key and the referenced key appear as the FIRST (leftmost) columns in an index, in the same order in the foreign key and the referenced key…
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 13 Comments
…wrong it > is frequently told by people with traditional database background. > Things are different with MySQL…Indexes This item was not in…possibilities. Also, indexing the full width of very wide columns will take up tremendous amounts of memory and disk. Because indexes…
Post: Merge Tables Gotcha
May 9, 2007 By 4 Comments
…possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: const rows: 1 Extra: Using index 1 row in set (0.00 sec) In…key in MySQL manual Here is what it says: Note that the a column is indexed as a PRIMARY KEY in the underlying MyISAM tables, but not in…
