…row in set (1.70 sec) Here is explain if someone curious, it did not really change beside key lengths: mysql…rows: 26 Extra: 2 rows in set (0.00 sec) So what about Innodb ? Innodb executed the same query in 2…. Char columns completes in 4.5 seconds on Innodb which is about 50% slower compared to …
Comment: Innodb vs MySQL index counts
November 30, 2011 By 6 Comments
…column missing): > select * from test; +—-+——-+———-+ | id | data | foo | +—-+——-+———-+ | 1 | 49999 | NULL | | 2 | 1000 | some foo | +—-+——-+———-+ 2 rows in…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 30 Comments
…columns. In practice you can also often use 4th variant which is not comparable…row MySQL will have to perform OS system call to read the row…rows: 225690 Extra: 2 rows in set (0.10 sec) Because we refer state by name, which is unique,it is pre-read and query…
Post: Quickly finding unused indexes (and estimating their size)
December 5, 2012 By 2 Comments
…. In either case, you may want to compare or…query this view to see my indexes: mysql> select * from all_indexes limit 1 \G *************************** 1. row… 1 COLUMN_CNT: 1 COLUMN_NAMES: last_name 1 row in set …total_size / ( 1024 * 1024 ), 2) as index_size_…disk are still the same old size. If you…
Post: The story of one MySQL Upgrade
October 8, 2010 By 8 Comments
…in sync. mk-table-checksum can use replication to check consistency but comparing 2…MySQL to see what is different in the tables. It turned out one of the float columns stored “-0″ in MySQL…same position again and used tcpdump and mk-query…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…compared to doing batched index lookups (BKA). However, in Test C the cost of hash join remains the same…query would be reading 1/3 the number of rows in the table orders (left operand), and so MySQL…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…the number of rows that match the condition ‘key_column=x’. You… buffer is small and there were 2 MRR range scans needed. …less the same for MariaDB 5.5 when compared to MySQL 5.5,…in-memory, in fact MRR adds extra sorting overhead which means that the queries are just a bit slower as compared to MySQL…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
…rows in set (0.00 sec) The table contains 1.000.000 rows with mostly unique “c” column. mysql…
Post: COUNT(*) vs COUNT(col)
April 10, 2007 By 45 Comments
… | +———-+ 1 row in set (0.00 sec) mysql> select count(val) from fact; +————+ | count(val) | +————+ | 7216582 | +————+ 1 row in set (1.17 sec) mysql> select count… table MySQL has cached number of rows in this table. This is why it is able to instantly answer COUNT(*) and COUNT(val2) queries… in this case doing full table scan only if it is needed because column can be NULL. Now lets try few more queries: mysql…
Post: PBXT benchmarks
April 8, 2007 By 14 Comments
…2 cpu MHz : 1800.163 cache size : 1024 KB 4GB of RAM MySQL version We used MySQL…column is stored in key. Interesting InnoDB scalability is pretty bad for this query…rows. General notes In general PBXT looks pretty good. To be honest I did not expect such results. The one problem comparing…
