… complete answers: Q: Can you compare the use of subqueries/multiple joins vs. multiple queries (e.g. temp tables)? For performance, it’s… another column, and reinitializing the sequence after making certain insert/update/delete operations. If you have a dataset that changes infrequently…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… also updates groups with some metadata: BEGIN; INSERT INTO users_groups (user_id, group_id) VALUES (100, 1); UPDATE groups SET last_joined=NOW(), last_user_id=100 WHERE id=1; COMMIT; How often might multiple users join the same…, how above moving the ‘joined‘ column to the users_groups table so we don’t need to update the parent group row…
Post: The Doom of Multiple Storage Engines
May 8, 2010 By 22 Comments
… file when all transaction engines have their own ! Quality Assurance Multiple storage engines are much more complicated to test. And I… using multiple storage engines in the query you need to test all kinds of combination such as running multi-table update joining PBXT… enough. In fact people already do not love to mix multiple storage engines very actively because of potential complications involved. Now…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
…way of using Multiple Tables to solve Table Locks problem you can also use multiple Key Caches …use activity. I just summed rows modified and updated but you can surely use different formula …4000000000)),”;”) cmd from information_schema.table_statistics ts join information_schema.tables t on t.table_…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
… matching range from some pre-generated table and use the join to retrieve the rows from original table: mysql> show create… get better performance by joining data to yet another table though why it does not work for multiple group remains question to check with MySQL Optimizer team 
UPDATE: I just heard back from…
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
… As you can see in this case the query self joins the table so we observe 2 table instances (note – same… 53173, OS thread handle 0x7ff75963b700, query id 3929840 localhost root Updating update sbtest set c=concat(c,’c') TABLE LOCK table `sbtest… because update needs to lock the rows in exclusive mode. Similar to IS lock IX is rather lose – I can have multiple update…
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 … followed certain execution plan. Multiple flags allowed in a comma-separated string. [qc_miss, full_scan, full_join, tmp_table, tmp_table… how verbose the messages to your slow log will be. Multiple flags allowed in a comma-separated string. [microtime, query_plan…
Comment: Using Flexviews - part one, introduction to materialized views
December 19, 2012 By 3 Comments
… a MV. The problem is these kinds of queries have multiple LEFT-JOINS (About 5-10 at any given time). I’ve… referenced JOINS is altered,ie.. If i have a MV on books and change the autor name the MV is updated, but…
Post: Using Flexviews - part one, introduction to materialized views
March 23, 2011 By 3 Comments
… contents of the result set are updated periodically, not each time the view is accessed. If multiple statements access the same view… joined together and pre-aggregated, CPU and memory usage may be reduced compared to computing the results. You can often generate multiple…. And some drawbacks: Not all SQL syntax supported (no outer join), no non-deterministic functions, etc. There is overhead for change…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…the changelogs collected by FlexCDC to update the snapshot to reflect the … The refresh algorithm computes changes in multiple transactions. After each transaction it … mview_table_alias: o mview_join_condition: NULL mview_join_order: 999 *************************** 2. row ***************************…
