Home |  MySQL Buzz |  FAQ |  Feeds |  Submit your blog feed |  Feedback |  Archive |  Aggregate feed RSS 2.0 English Deutsch Español Français Italiano 日本語 Русский Português 中文
Showing entries 1 to 2

Displaying posts with tag: WAITING for table (reset)

Alter waiting on Select statement to complete
+1 Vote Up -0Vote Down

A few days ago, we faced an interesting problem on one of our customer’s slave mysqld servers.  An Alter for adding a new column was run on master server took 542 seconds where as it took few hours on the slave server to complete due to a SELECT blocking the Alter was not allowed to complete.

Here is the the select on the master server and it’s execution time from the binary logs.

# at 825737566
#110720 19:55:21 server id 31415  end_log_pos 825737730         Query   thread_id=83250629      exec_time=542   error_code=0
use collect/*!*/;
SET TIMESTAMP=1311216921/*!*/;
/*!\C latin1 *//*!*/;
SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8/*!*/;
ALTER TABLE `track` ADD `source_track_id` int(10) UNSIGNED NULL DEFAULT NULL  AFTER `vendor_track_id`
/*!*/;

Alter statement completed well on the



  [Read more...]
Create Table Like Scalability Issues
+4 Vote Up -0Vote Down

When we wanted to quickly process intermediate data by using temporary or heap tables; then its normal tendency to create a table like its source table; so people will simply opt for CREATE TEMPORARY TABLE temp_table LIKE source_table.

This is an easy and convenient way. But the problem is if you have a simple stored procedure or code module that gets executed frequently, then you might indirectly experience a slow-down in the performance if your source_table is large enough and highly contended. Things will be really worst if concurrent threads starts using the source_table or in combination of source_table and CREATE LIKE.. statements and can lead to disaster scalability issues. The main reason for the post is; I noticed from SHOW PROCESSLIST from random servers where X

  [Read more...]
Showing entries 1 to 2

Planet MySQL © 1995, 2014, Oracle Corporation and/or its affiliates   Legal Policies | Your Privacy Rights | Terms of Use

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.