June 19, 2013

Post: A recovery trivia or how to recover from a lost ibdata1 file

June 3, 2011 By 8 Comments

…column. With a modified schema, the recovery completed. The customer was able to download the tables in MyISAM format and then he just convert…

Filed Under: MySQL

Post: MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By 4 Comments

…to convert sort to the union for small ranges. Q: In the case of a junction table…how mysql use index for group by? A: If you have Index on the column MySQL can avoid temporary table…

Filed Under: Insight for DBAs, MySQL

Post: How to recover deleted rows from an InnoDB Tablespace

February 20, 2012 By 4 Comments

…to the error log. mysql (employees) > CREATE TABLE innodb_table_monitor (id int) ENGINE=InnoDB; TABLE: name employees/salaries, id 18, flags 1, columns…table_defs.h so it will be necessary to recompile the tool. To help us in the task of converting the schema definition to…

Filed Under: Insight for DBAs, MySQL

Post: TMP_TABLE_SIZE and MAX_HEAP_TABLE_SIZE

January 19, 2007 By 17 Comments

…to it you should increase tmp_table_size to appropriate value and avoid using blob/text columns which force table…table after which it will be converted to MyISAM. To make things more confusing this is not what you would read in MySQL…

Filed Under: Insight for DBAs Tagged With: ,

Post: Flexviews - part 3 - improving query performance using materialized views

April 4, 2011 By 20 Comments

…to convert SQL to the Flexviews API (see convert.php below) Refresh methods The incremental refresh method The incremental refresh method uses table…how you can use this summary to calculate the number of lines in the order_lines table, three orders of magnitude more quickly than COUNT(*). mysql…

Filed Under: Insight for DBAs, MySQL

Comment: Database problems in MySQL/PHP Applications

August 11, 2006 By 13 Comments

…to do row lookups by multiple columns of varchars is likely. Don’t do it. I can think of…of MySQL. If nothing else, it makes replicating a subset of the data much easier. > Regarding if you use many tables…of converting your varchars to chars for example), then having to…

Filed Under: Insight for Developers Tagged With: , ,

Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

…to create an *InnoDB* table with a single VARCHAR column named “value”. OK, sounds easy enough: mysql: SHOW CREATE TABLE innodb_myisam_stopword\G *************************** 1. row *************************** Table…to take the MyISAM full-text parser code, convert it to…

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

Post: Innodb row size limitation

April 7, 2011 By 12 Comments

…mysql…converting from a native language character set to…table definition, but at row insertion. You may just have a table with 50 variable length columns…columns aren’t requested as part of a row-read, they don’t have to be touched at all. Of…

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

Post: Timezone and pt-table-checksum

September 25, 2012 By 1 Comment

… to a default value of CURRENT_TIMESTAMP.  From the manual, here is how MySQL handles timezone locality with timestamp fields: Values for TIMESTAMP columns are converted… to get the actual rows in need of syncing, it will not find those rows even though pt-table-checksum reported the chunk as out of…

Filed Under: Insight for DBAs, MySQL, Percona Software

Post: Lost innodb tables, xfs and binary grep

November 9, 2010 By 12 Comments

…how data was lost: MySQL had a dedicated partition on XFS file system Server was running innodb_file_per_table…to have a lot of data to scan and you have to…of percona recovery toolset, with some additional converters so we can match against various date/time columns…

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