June 20, 2013

Post: Percona Server 5.1.69-14.7 now available: A drop in replacement for MySQL

June 10, 2013 By 3 Comments

…in replacement for MySQL, downloads are available  here and from the Percona Software Repositories. Based on MySQL…records are overwritten by the new log data. In some corner cases this could lead to assertion errors in…tables in INFORMATION_SCHEMA (CLIENT_STATISTICS, INDEX_STATISTICS, TABLE…, deleting…

Filed Under: MySQL, Percona Server, Percona Software Tagged With:

Post: MySQL Query Patterns, Optimized - Webinar questions followup

June 3, 2013 By 2 Comments

…MySQL Query Patterns, Optimized” for Percona MySQL Webinars.  If you missed it, you can still register to view the recording… certain insert/update/delete operations.  If you …in this case to force MySQL to scan the `title` table first, grouping by kind_id in index order.  This made the first table in…

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

Comment: MySQL Partitioning - can save you or kill you

April 30, 2013 By 45 Comments

… _no_ parallel queries (within a single connection) anywhere in any ‘free’ variant of MySQL. PARTITIONs are scanned one at a time. (Please… “delete records from this table, those will be quicker, as they will come out of the partition, not the whole table“: * If the DELETE is… one record. PARTITIONing makes very little difference. * If it cannot prune, then partitioned would be slower, since it would attempt the DELETE in…

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

Comment: MySQL Partitioning - can save you or kill you

April 30, 2013 By 45 Comments

… single table, where probably only recently read records will be cached, resulting in more disc reads. 2. If you need to delete records from this table, those will be quicker, as they will come out of the partition, not the whole table. 3… on a partitioned table, as Mysql can fire off one thread per partition (at least I have seen this happen in a MyIsam…

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

Post: How to debug long-running transactions in MySQL

March 8, 2011 By 6 Comments

…query log, and examine the log. In MySQL 5.1 and newer with the…some INFORMATION_SCHEMA tables that make this simple. Just query the tables, and if…the disk. #!/bin/bash # Begin by deleting things more than 7 days old find…transaction can possibly have undo log records! The greater moral of this story …

Filed Under: Insight for DBAs, MySQL

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

February 26, 2013 By 1 Comment

…table_name | | | use_stopword | 1 | | table_state | 0 | +—————————+———+ 10 rows in set (0.00 sec) mysql> delete…

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

Post: How to recover deleted rows from an InnoDB Tablespace

February 20, 2012 By 4 Comments

… need to delete the records of the employee 10008 from the table “salaries”. After the “accidental” deletion of rows you should stop MySQL, take a… directory with some subdirectories inside, one for every single index in the table: ~/recovery-tool# ls pages-1329221407/FIL_PAGE_INDEX/ 0…

Filed Under: Insight for DBAs, MySQL

Post: MySQL Slow query log in the table

May 31, 2007 By 1 Comment

As of MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file as you had in previous versions… sort records by physical position quickly without need to have indexes would be quite handy I also should tell log table implementation in MySQL… of in regards to avoiding trouble. For example you can’t ALTER log table while query is running, neither you can delete rows…

Filed Under: Insight for DBAs Tagged With:

Post: Concatenating MyISAM files

November 19, 2012 By 5 Comments

… – check record delete-chain – recovering (with sort) MyISAM-table ‘test_concat’ Data records: 3 – Fixing index 1 Data records: 6 And then, back in mysql: mysql> use test Database changed mysql> flush tables; Query…

Filed Under: MySQL

Post: Using Flexviews - part two, change data capture

March 25, 2011 By 26 Comments

… an appropriate name. The Binary Log is the MySQL log which records changes to tables in the database. FlexCDC reads the binary log to… in a moment. Lets create a table, insert some rows, add a change log, delete rows and then insert some more of them: mysql… rows affected (0.00 sec) Records: 2 Duplicates: 0 Warnings: 0 And delete data in a second transaction: mysql> delete from test.demo where c1…

Filed Under: Insight for DBAs, Insight for Developers, MySQL
« Older Posts