June 18, 2013

Post: MySQL Query Patterns, Optimized - Webinar questions followup

June 3, 2013 By 2 Comments

…the query optimizer take care the execution decisions? Since they are all logically the same, I believe it should all translate to the same…values against multiple columns in a compound index, then the order would matter, and it would have to match the order of columns in the…

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

Post: Implementing SchemaSpy in your MySQL environment

June 4, 2013 By 2 Comments

…the impression that this is the only component of the tool.  There are additional tabs: Tables – Names, number of children, parents, count of columns, row…column tables, incrementing column names in tables, and tables with the string NULL instead of the actual SQL NULL value…

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

Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

…the word ‘arizona’ appears in over 6900 of the 7150 rows, and the word ‘records’ appears in 7082 of…the “value” column the PK, but neither of those worked. Also, trying to set innodb_ft_user_stopword_table produced the same…

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

Post: A case for MariaDB's Hash Joins

May 31, 2012 By Leave a Comment

…scanning the right operand and for each row scanned performing a lookup in the hash table by using values of the columns participating in the equijoin condition. The … as compared to doing batched index lookups (BKA). However, in Test C the cost of hash join remains the same but the cost of BKA …

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

Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

March 21, 2012 By 10 Comments

…the values returned from Step 1 are sorted by the secondary key column ‘key_column‘, and then for each value of ‘pk_column‘ which is a part of the…the counters behave with MRR, but the value for counter Handler_read_key is more or less the same for MariaDB 5.5 when compared…

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

Post: Multi Column indexes vs Index Merge

September 19, 2009 By 31 Comments

…the query takes 360ms Note also the estimated values of “rows” is very wrong here. This happens because Optimizer assumes columns…of rows it will find using both indexes and as they are about the same it picks smaller index. The…

Filed Under: Insight for DBAs, MySQL Tagged With:

Post: To pack or not to pack - MyISAM Key compression

May 13, 2006 By 4 Comments

…the block boundaries – first index value is stored fully while for following value index will contain value of the bytes sames as in previous cases + the… the biggest reason joins using string keys is so much slower compared … of benchmarks now. I’ve created simple table with 100.000 rows with columns…

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Post: Data compression in InnoDB for text and blob fields

May 30, 2012 By 2 Comments

… FROM `t1` WHERE `id` < 1000 compare this to: SELECT AVG(LENGTH(COMPRESS…the choice of ROW_FORMAT=COMPACT and ROW_FORMAT=REDUNDANT where InnoDB stored the first 768 bytes of variable length columns (BLOB, VARCHAR, TEXT) in the… that is the same value of the InnoDB page size of 16KB?  As the fine MySQL…

Filed Under: Insight for DBAs, Insight for Developers, MySQL, Percona Software

Post: Using Flexviews - part two, change data capture

March 25, 2011 By 26 Comments

…the transaction order and the source of the changes, respectively. Finally, note that the two insertions happened inside of the same transaction, and that the insertions happened before the…

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

Post: Dynamic row format for MEMORY tables

September 6, 2011 By 5 Comments

…the same for both row formats. (Speaking very strictly, the VM Peak value is not comparable due to slightly different number of rows inserted). In the…

Filed Under: MySQL, Percona Software
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