… by aggregating query log with mk-query-digest. When I filtered out only queries of this pattern and got a simplified…_next,QUICK_RANGE_SELECT::get _next,rr_quick,sub_select,do_select,JOIN::exec,mysql_select,handle_select,execute_sqlcom_select,mysql_execute_command,my sql_parse,dispatch_command…
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…filtering…
Post: A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
… the view and we add a filter condition on c1, the view is accessed quicky: mysql> select c1, count(*) from v1 where c1… view using a filter on c1, performance is not good. MySQL is scanning the entire table to produce the result: mysql> select * from v2…) In review, I like views for their convenient encapsulation of SQL logic that would usually have to be repeated in…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
…sql/filesort.cc patching file sql/log.cc patching file sql/log_event.cc patching file sql/my_time.c patching file sql/mysql…sql/sql_cache.cc patching file sql/sql_class.cc patching file sql/sql_class.h patching file sql/sql_parse.cc patching file sql/sql_select.cc patching file sql/sql…
Post: Filtered MySQL Replication
November 7, 2007 By 8 Comments
…filtered or partial MySQL Replication (as of version MySQL 5.0) – there is enough gotchas with replication itself and getting things right with filtering…filtering being broken by developer forgetting this restriction and running one time update query without selecting…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
… only 29 air carriers in the table: mysql> select count(*), count(distinct UniqueCarrier) from dim_flightG *************************** 1…This VM was rebooted between tests. A SQL script was fed to the run_… performance continues to improve when grouping and filtering is used. Again, notice Q9. It …
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…, all in parallel. All joins, aggregation and filtering is done at the storage node level…. of compute resource which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl…2009) GROUP BY 1 ORDER BY NULL ) — AGGREGATION SQL: SELECT `origin_airport_id`, SUM(`count(*)`) AS `count(*)`,…
Post: MySQL Slow query log in the table
May 31, 2007 By 1 Comment
…MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file…SQL as it easy to filter all queries which happened within certain time interval (ie after I’ve done some changes) or filter…new queries in the end you can do SELECT * FROM (SELECT * FROM slow_log ORDER BY start_time…
Post: MySQL extensions for hosting
April 24, 2008 By 11 Comments
…customers simply because their skills in SQL are limited. The real life …with some strategic decisions. Sample outputs: mysql> SHOW USER_STATISTICS LIKE ‘hosting2′\G *************************** 1. …schema support to allow SELECT query transformations, joins and better filtering for the statistics…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…SQL used for this test together with its EXPLAIN output as returned by MySQL 5.5 is as follows: SELECT…| select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra | …
