June 20, 2013

Post: MySQL Query Cache

July 27, 2006 By 70 Comments

…of usable memory – Queries are constantly being invalidated from query cache by table updates, this means number of queries in…to be cached. Counting query cache efficiency There are few ways you can look at query_cache efficiency. First looking at number of…

Filed Under: Insight for DBAs Tagged With:

Post: Advanced index analysis with mk-index-usage

November 11, 2010 By 2 Comments

…tables in a database, so you can query them with SQL. I logged all queries to the blog for a little while, and then secure-copied the query…query these tables any way you want. The documentation includes a number of other canned queries…

Filed Under: Insight for DBAs, MySQL

Post: Sphinx search performance optimization: multi-threaded search

January 16, 2013 By 10 Comments

…to check – look at your Sphinx query log and look at the number of results matched per query…to split data, you may want these to be ranges by using a helper table in MySQL to define those ranges, mixing it with sql_query…

Filed Under: MySQL Tagged With: , , ,

Post: Sphinx: Going Beyond full text search

July 23, 2007 By 18 Comments

…to mention counting number of links (and number number of distinct forum sites) pointing to the given URL or graphs showing number of links per day. To…SQL databases rather than full text search applications. Group By was added to Sphinx so we could search number of matches per day, or number of…

Filed Under: Insight for Developers Tagged With: ,

Post: Is VoltDB really as scalable as they claim?

February 28, 2011 By 3 Comments

…in the cluster; high availability is ensured by keeping more copies of each partition. You query VoltDB with stored procedures, not with arbitrary SQL queries…count from 1 to 12, for k-factors of 0, 1, and 2. The k-factor is the number of redundant copies of…

Filed Under: Benchmarks, MySQL

Post: The new cool MySQL patch has landed! Check your queries performance!

October 31, 2007 By 16 Comments

…in seconds) query spent either waiting to enter the InnoDB queue or inside that queue waiting for execution. InnoDB_pages_distinct tells the number of…table: No Disk_tmp_table: No # Filesort: No Disk_filesort: No Merge_passes: 0 # No InnoDB statistics available for this query SELECT COUNT…

Filed Under: Percona Software Tagged With: , ,

Post: Are you designing IO bound or CPU bound application ?

December 20, 2006 By 10 Comments

…query and these rows are “random access” to large tables (so chances they would require physical IO are high) I would highlight this query…number of messages in the mailbox at least to draw “pager”. Easy solution is to do select count(*) from messages where user_id=134 or use SQL…

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Post: Speeding up GROUP BY if you want aproximate results

March 7, 2008 By 24 Comments

…to count how many hits come to the pages which get more than couple of visits per day. We had SQL logs in the database…to share which I use a lot when I want to analyze data distribution but table is to large is to just limit it to first number of…

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Post: Analyzing air traffic performance with InfoBright and MonetDB

October 2, 2009 By 50 Comments

…to analyze a bigger dataset and I took public available data http://www.transtats.bts.gov/DL_SelectFields.asp?Table…of RAM and Dual Intel(R) Xeon(TM) CPU 3.40GHz. InfoBright (ICE) version: 5.1.14-log build number…in different queries. First favorite query for any database benchmarker is SELECT count…

Filed Under: Benchmarks, MySQL Tagged With: , , ,

Post: MySQL caching methods and tips

April 4, 2011 By 5 Comments

…of change in the database tables. This results in unpredictable and therefore, undesirable, performance. The other big problem with the query…of pages is a good way to reduce the number of round trips to the cache. Summary tables Queries that access a lot of…

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