… remember at that time MySQL only had ISAM tables with table locks and no transactions support. Of …set it to replace multiple values at the same time just as you have multiple value INSERT. As…was – many people tried to use it like update accessing previous column value, for example doing something…
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 13 Comments
… so. > Using multiple tables gives some very important benefits – your data > becomes managable, your ALTER TABLE or OPTIMIZE TABLE > now locks small table for few… indexes. Foreign key references may add processing time to inserts, updates, and deletes but there are other benefits. Also – if you…
Post: Differences between READ-COMMITTED and REPEATABLE-READ transaction isolation levels
August 28, 2012 By 3 Comments
… resultset that you saw at 5AM. This is called MVCC (multiple version concurrency control) and it is accomplished using row versioning… SELECT … FOR UPDATE is run at 5AM, and an UPDATE is run at 5PM (“UPDATE some_table where id > 100″) then the UPDATE will change the same rows that SELECT FOR UPDATE locked…
Post: Multiple purge threads in Percona Server 5.1.56 and MySQL 5.6.2
May 3, 2011 By 13 Comments
…2 one can have multiple dedicated purge threads. Percona Server 5.1 supports multiple purge threads too, …innodb_file_format=barracuda innodb_file_per_table max_connections=2000 table_cache=2000 Percona Server 5….the scripts and results) and here are the updated 5.6.2 results. The difference against …
Post: Efficient Boolean value storage for Innodb Tables
April 23, 2008 By 6 Comments
… have the task of storing multiple of boolean values (yes/now or something similar) in the table and if you get many…_increment: NULL Create_time: 2008-04-24 00:54:18 Update_time: NULL Check_time: NULL Collation: latin1_swedish_ci Checksum…_increment: NULL Create_time: 2008-04-24 00:37:48 Update_time: NULL Check_time: NULL Collation: latin1_swedish_ci Checksum…
Post: Long PRIMARY KEY for Innodb tables
October 3, 2006 By 8 Comments
… default ’0′, `ts` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP, PRIMARY KEY (`url`,`thumb_width`,`thumb_height`) ) ENGINE… 2 IOs as with non-clustered tables. The other benefit – it is typical to show multiple thumbnails from the same album/domain… are doing in index ? In this case we could have multiple thumbnail sizes for the same image which is why they…
Post: MySQL 5.6: Improvements in the Nutshell
January 27, 2013 By 16 Comments
… Fragmentation – Reduced Locking for Partitioned tables – Reduced Contention for LOCK_open – Support for multiple table_open_cache instances – Large … – Improved File I/O Instrumentation – Improved EXPLAIN – - Explain for UPDATE/DELETE queries – - JSON output with more information – Optimizer Tracing…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
For a couple of months there have been no updates to our msl patch, however recently I managed some time … execution plan. Multiple flags allowed in a comma-separated string. [qc_miss, full_scan, full_join, tmp_table, tmp_table_on_disk, filesort… how verbose the messages to your slow log will be. Multiple flags allowed in a comma-separated string. [microtime, query_plan…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
… data for date range for multiple of groups (these can be devices, pages, users …. etc) CREATE TABLE `info` ( `id` int(10) unsigned… retrieve the rows from original table: mysql> show create table dl \G *************************** 1. row *************************** Table: dl Create Table: CREATE TABLE `dl` ( `myday` date NOT NULL… yet another table though why it does not work for multiple group remains question to check with MySQL Optimizer team 
UPDATE: I just…
Post: Using MMM to ALTER huge tables
March 27, 2008 By 11 Comments
… INTO table VALUES (id,value1,value2,..)”; good e.g. “INSERT INTO tables (id,col1,col2,..) VALUES (id,value1,value2,..)”), deletes or updates of… is to ensure replication has caught up. If you have multiple pairs doing some changes in parallel and you want to…; db1 will receive the updates that were executed by changes.sql or some other script and rebuild its tables. When replication on…
