June 18, 2013

Post: Checking for a live database connection considered harmful

May 5, 2010 By 38 Comments

…database(connection, sql, retries=1) while true try result=connection.execute(sql) return result catch InactiveConnectionException…to use the same code that fixes the race condition. Again, if the connection is down, you’ll find out when you try to… it’d be a big help to apps when they grow. It’s…

Filed Under: Insight for Developers, MySQL

Post: InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By 1 Comment

… a very big fan of MyISAM; I would argue that in most situations, any possible advantages to using MyISAM…is syntactically identical to MyISAM full-text search, in the sense that the SQL required to run a MATCH …..when I run an FTS query against both MyISAM and InnoDB I will get back the same results;…

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,

Comment: How to find wrong indexing with glance view

March 8, 2010 By 27 Comments

…result in 1 row matching. So to circumvent that you need to help it out with optimizer hints like straight_join to…using version 5.0.45 btw). This great fun when you’re using an ORM like SQL Alchemy and want to avoid writing sql… if we did it would be a big deal – requiring system down time etc. New…

Filed Under: Insight for DBAs Tagged With:

Post: Quickly finding unused indexes (and estimating their size)

December 5, 2012 By 2 Comments

…indexes. To accomplish merging multiple result sets, …use some clever SQL to generate the precise ALTER TABLE statements to drop these indexes, an exercise left to… need to update our droppable_indexes view to use that …big each index is if we dropped it (not big… story when it comes to reclaiming disk …

Filed Under: Insight for DBAs, MySQL, Percona Software

Comment: HandlerSocket on SSD

November 3, 2010 By 9 Comments

…, he reported a result of 750K qps. In your benchmark the performance (when data set fit in…between 750K qps and 10K qps is pretty big. Both you and Yoshinori benchmarked lookup by PK…to regular SQL, what type of performance would you get? Seems like 10K qps is very achievable even using regular SQL…

Filed Under: Benchmarks

Post: Why MySQL could be slow with large tables ?

June 9, 2006 By 141 Comments

…,MS SQL, PostgreSQL …to take into account is the fact – situation when data fits in memory and when…-server partitioning to use combined …big scans. This will reduce the gap but I doubt it will be closed. Joins Joins are used to…to manually split query into several, run in parallel and aggregate result…

Filed Under: Insight for DBAs Tagged With: ,

Post: The two even more fundamental performance metrics

May 5, 2011 By 6 Comments

…useful, but it certainly is, because it can make it obvious when something is really an aberration and you need to…database servers. As a result, completion times shouldn’t…to some lock, the outbound packets would have actually dropped off sharply, leaving a big…of the SQL in hand, we might be able to …

Filed Under: MySQL

Post: MySQL 5.5 and MySQL 5.6 default variable values differences

February 21, 2013 By 8 Comments

… results I’ve been looking at changes to default variable values. To…too small to be practical if someone tries to enable it. sql_… increased from 500 to 5000. If you’re using innodb_thread_…by default. This is very big change and is good one…now. The exceptions have been when you have large number …

Filed Under: Insight for DBAs, MySQL Tagged With: , , ,

Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown

March 14, 2013 By 2 Comments

…results. What was happening? Well, in order to understand it I must provide you with more background information. My buffer pool was big…when the condition is very selective and the buffer pool is effective. There is no workaround, using…

Filed Under: Events and Announcements, Insight for Developers, MySQL Tagged With: , ,

Post: Power of MySQL Storage Engines

March 5, 2007 By 3 Comments

… leads to customer winning. When Falcon looses to Innodb in certain cases it makes Jim to …SQL layer is kind of fixed same for all. This dramatically limits what you can do. Such limit is not a big…to checking number of rows in result set and LIMIT implementation – these can optimized but not by use…

Filed Under: Insight for DBAs Tagged With: , , ,
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