…SELECT query executed against the wp_options table. Another thing to note is the last line in the output the # MISC part, it tells you how…The first row in the table above shows the Count of number of times this query was executed. Now let’s take a look at the values in the…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
Post: Recovering Innodb table Corruption
July 4, 2008 By 19 Comments
…In second case I’m running with innodb_force_recovery=1 and as you can see even though I get the message in the…in the table and we need to somehow skip over it. To do it we would need to find max…
Post: When should you store serialized objects in the database?
January 21, 2010 By 42 Comments
…to store the settings that differ from the default values. The second situation where I can see this technique making sense, is that when you update the…to know that SELECT * is bad. This creates a pattern where SELECT * is not optional. In practical terms I would expect this increases the…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…the query and the information mysqlsla outputs about it (execution times, etc), the EXPLAIN plan, and the desired modifications to the query or the table. We explain how to…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
…tables once) Same as with select case I could not see any measurable difference between two tested innodb_open_files values…in the list. I guess Heikki knows how to implement LRU in the…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
…in set (0.00 sec) The table contains 1.000.000 rows with mostly unique “c” column. mysql> explain select…second to do, but it is not how it happens in practice. mysql> show global status like “key%”; +————————+———+ | Variable_name | Value…set global max_heap_table_size=1000000000…
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
…in Innodb row level locks are implemented by having special lock table, located in the…to the pages (column j was populated by md5(rand()) values) : mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…in the system. To get an even distribution, the test data was hashed over the values in the date_id column. There will be another blog post about the…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
…VALUES (RAND()); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO t(c) SELECT…in the table makes any difference: mysql> SET expand_fast_index_creation=OFF; Query OK, 0 rows affected (0.00 sec) mysql> ALTER TABLE…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…how to use this info to improve MySQL Performance. To…values are per second. If you’re planning to use these values make sure they are sampled over decent period of time. In the…tables in use 1, locked 0 MySQL thread id 8079, query id 728899 localhost root Sending data select…
