…SQL query optimizer and see how easy it is? ;-) Generative …to add a column to the table, and populate the rows you want to choose (movies, in this case) with values known to…columns in a compound index, then the order would matter, and it would have to match the order of columns in the index…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… a single row (well, the PRIMARY KEY index entry for that row). This means typically … above, how above moving the ‘joined’ column to the users_groups table so we don’t need to update … Choosing a system to replicate your data to a distributed system requires tradeoffs. Most of us are used to …
Post: Air traffic queries in MyISAM and Tokutek (TokuDB)
November 5, 2009 By 26 Comments
… base point to see how column-oriented-analytic engines are better here. However, take into account, that for MyISAM we need to choose proper indexes to execute queries effectively, and there is pain coming with indexes: – load of data is getting slower; – to design proper indexes is…
Post: Choosing innodb_buffer_pool_size
November 3, 2007 By 39 Comments
…You also may choose to set buffer …step would be to decide How Much …to adaptive hash indexes, ability to buffer writes and number of other factors so you just want to make your OS to give a way to…to get them in the swap. Make sure however the swapping is not happening ie your VMSTAT “si/so” columns…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…choose your aggregation to match the order of your common queries and b) choose your primary key correctly. Let’s go back to… you still have to think about how to avoid enormous tables that are hard to maintain, back up,…a set of primary key columns. And not only will every index be a little narrower,…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… that traditional index lookup (for non-index-only columns) involves, reading an index record, and then using the PK column value in the index record to make… in how counter is calculated inside MariaDB? Other Observations Sometimes both for MariaDB 5.5 and MySQL 5.6, the optimizer chooses…
Post: The MySQL optimizer, the OS cache, and sequential versus random I/O
April 28, 2008 By 17 Comments
…all the dimension columns are indexed on every table, and there’s a separate index on every column in the WHERE …No one ever let it finish to see how long it would run. How do I know it will run… table, and do index lookups in the two dimension tables. MySQL doesn’t want to choose this join order, …
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…what the Hash Join is, how it works and for …to do an index range scan on the secondary key o_orderdate which results in random scans of the PK to fetch the columns…to manually enable and disable the join algorithms for the optimizer to choose from. In MariaDB, every algorithm has a number given to…
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
… can use index to filter records before fetching any rows. How much it will…(City, Gender, Age, Available). So mysql can choose between two which is more selective…columns, it’s up to you decide what to do. 1. http://www.mysqlperformanceblog.com/2006/08/10/using-union-to-implement-loose-index-scan-to…
Post: Full Text Search Webinar Questions Followup
August 24, 2012 By 5 Comments
…to memory was that when I tried to create an InnoDB FT index before declaring the `FTS_DOC_ID` primary key column…how to use one technology or the other, and some may compare one technology to…
