…just dumps all MySQL tables into a …be preferred by the I/O scheduler over random I/O coming from MySQL, but also such large…being filled with random information additional I/O occur slowing…MySQL data files do not comply with this requirement. The trick could be used here perhaps to read the file with…
Post: MySQL extensions for hosting
April 24, 2008 By 11 Comments
…being used at all and could be candidates for dropping. All the patch features will surely be…slow log live, but that is a bit ugly solution. That is where this patch can be very useful. With simple MySQL…
Post: Finding out largest tables on MySQL Server
February 4, 2008 By 27 Comments
…tables on MySQL instance is no brainier in MySQL 5.0+ thanks to Information Schema …or may be there is long primary key with Innodb tables. Of course it also could be perfectly fine tables but …be rather slow if you have a lot of large tables. On this instance it took 2.5 minutes to run for 450 tables…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
…Be careful however with these nested IN clauses. MySQL has to internally build all possible combinations for row retrieval which ma become very slow…could only do it on idle box so as in MySQL…table: mysql…
Post: Logging MySQL queries from the client instead of the server
February 2, 2011 By 2 Comments
…slow query log” is the single most valuable way to examine query execution on your MySQL server. Queries are logged with… that nobody could get into … the potentially large and hard…table and then use SQL to analyze the queries; but this is quite a bit harder, because similar queries need to be…
Post: Fighting MySQL Replication Lag
September 22, 2008 By 7 Comments
… updates instead of one large update to help MySQL replication lag it…table scan in MySQL 5.0 (even if there are no spam posts) which will load slave significantly. You can replace it with… (list of ids) If there could be many ids matched on the … simply space it out and slow down your batch job (such …
Post: MySQL Session variables and Hints
December 28, 2006 By 2 Comments
… even though it also can be quite helpful and I believe …some complex way) – adding extra MySQL calls with possibly their own error control is… could do something like: SELECT SQL_SORT_BUFFER_SIZE=50000000 NAME FROM LARGE_TABLE …log (ie slow queries log) and SHOW PROCESSLIST so once could take it …
Post: Long PRIMARY KEY for Innodb tables
October 3, 2006 By 8 Comments
… with 1 IO not with 2 IOs as with non-clustered tables. The…large MyISAM tables in case of MySQL/System crash is painful and great to be …table scan for this table would also be slow as it is quite fragmented. Table however is not getting any table… ? In this case we could have multiple thumbnail sizes…
Post: The perils of InnoDB with Debian and startup scripts
January 28, 2009 By 13 Comments
…as large … be extremely slow…We could …with everything else going on. Look what happens: mysql> show processlist; +——+——————+—————-+————- | Id | User | State | Info +——+——————+—————-+————- | 7 | debian-sys-maint | NULL | CHECK TABLE…
Post: What do we optimize with mk-query-digest ?
December 15, 2009 By 2 Comments
… – general system overload, row level locks, table locks all could cause query response time to be unreasonable. If Slowest query is not interactive… perfectly possible to get bad performance with MySQL responsible for large portion of response time without any slow queries. We’ve seen pages which…
