…from the other side, things start to degrade. If you’re just setting up a test environment to get… TCP packets can actually result in performance that’s worse than a single NIC.] The other …query, but it’s always possible to build something more involved if that’s what you need. Q: What MySQL…
Post: Is your MySQL buffer pool warm? Make it sweat!
April 16, 2013 By 6 Comments
…mysql-host 127.0.0.1 –mysql-username playback –mysql-password PaSSwOrd –mysql-schema schema_name –query… 0.6 or later to get these features. Be aware …stream of queries. Benchmarks We benchmarked with slow query logs captured from our…chunk 3. The result is similar for every single graph, each …
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 64 Comments
… in MySQL 4.0 Query Cache was designed to work with single core… to get query result which is up to 60 stable. We can also get query…MySQL Query Cache is most useful for complex expensive queries, for which tracking exact rows used from query syntax may be hard. Query Cache Storage Engines MySQL Query…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
… get it. Most distributed engines work with rows. They break the queries…from all the nodes. A single temporary table is used to store the results from all the nodes. Since we are projecting results…MySQL storage nodes are supported. Amdahl’s law applies to the distributed processing. The results from…
Post: Upgrading MySQL
January 5, 2010 By 24 Comments
… MySQL 4.1 or changing JOIN evaluation in 5.0 (which could both cause different result set or make query not runnable in MySQL… like SELECT name FROM users WHERE id=5 you can probably go to the earliest MySQL version and still get same result. The more… Running single stream of queries with good speed is not enough. You also need to perform stress testing to ensure both MySQL does…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…query could return different results if executed twice and if a DDL was executed between the query…mysql.com/bug.php?id=67647 Metadata locking behaves differently for queries that are serviced from the Query…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
…query log with mk-query-digest. When I filtered out only queries…from 24 core system. For comparison you can checkSysbench Results which Vadim published. For read only workload we get 17x gain from…get_clust_rec_for_mysql,row_search_for_mysql…
Post: Is MySQL 5.6 slower than MySQL 5.5?
February 18, 2013 By 23 Comments
…get more repeatable results…single thread MySQL 5.5 is 11% faster than MySQL 5.6. If you disable Performance Schema in MySQL…MySQL 5.6 had more reasonable defaults as its goal ? Summary: Well, to be frank I expected more from MySQL…
Post: How to use tcpdump on very busy hosts
April 18, 2011 By 17 Comments
… even so they can skew results dramatically. Imagine a situation where a single connection sends two queries and gets two responses, with a response… response and second request are dropped by the kernel, the result – from mk-query-digest’s perspective – is that the database took 2R…
Post: MySQL VIEW as performance troublemaker
August 12, 2007 By 57 Comments
… table which just gets single row from the table by the key we think this is simple query, while can …query which just joined 2 tables… I ran EXPLAIN for it and got 200 of rows in the result…(*) cnt from comments group by user_id; Query OK, 0 rows affected (0.00 sec) mysql> select * from user_counts…
