…MySQL 5.6 code? As MRR was used in both MySQL 5.6 and MariaDB 5.5. Handler_mrr_rowid_refills counts…value for counter Handler_read_key is more or less the same for MariaDB 5.5 when compared to MySQL…
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
…procfs for MySQL process: root@ubuntu:/var/log/mysql# cat … can get the value from User Statistics *************************** 1. …avg 95% stddev median # ============ === ======= ======= ======= ======= ======= ======= ======= # Count 98 1753697 # Exec… (less than 10 ms) or needed more than that….
Post: Shard-Query adds parallelism to queries
November 15, 2010 By 16 Comments
…InnoDB, PARTITION p3 VALUES LESS THAN (’1988-02-01′) ENGINE = InnoDB, … PARTITION p253 VALUES LESS THAN (’2008-12-01′) ENGINE = InnoDB, PARTITION p254 VALUES LESS THAN (MAXVALUE) ENGINE … aggregation (count(*)) on a range of records. This table is partitioned by month which means that MySQL can …
Post: When EXPLAIN estimates can go wrong!
October 13, 2011 By 7 Comments
…count of rows: mysql [localhost] {msandbox} (foo2) > select count(*) from test_estimate where type=6 \G *************************** 1. row *************************** count…concentrated against a key value and that key value happens to be…per page. If there are less than 10 intermediate pages then all…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… of rows matches to particular index value or range. What is often forgotten …mysql> select count(pad) from large; +————+ | count(pad) | +————+ | 31457280 | +————+ 1 row in set (4 min 58.63 sec) mysql> select count… (12GB) table was scanned in less than 5 minutes. Now if we …
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… just for new connections as in MySQL. This is very helpful for …to set it back to a value greater than 0, because otherwise you …Count of number of times this query was executed. Now let’s take a look at the values… even compress the values stored in the option_value column so that less data is…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…SQL, but right now only MySQL storage nodes are supported. …is not required — 2 items is less than the inlist-merge-threshold of …VALUES(`origin_airport_id`), `count(*)`=`count(*)` + VALUES(`count(*)`), `sum(AirTime)`=`sum(AirTime)` + VALUES(`sum(AirTime)`), `sum(DepDelay)`=`sum(DepDelay)` + VALUES…
Post: Efficient Boolean value storage for Innodb Tables
April 23, 2008 By 6 Comments
… can see for MyISAM 10 columns take just 7 bytes – less than a byte per column. This is just minimum row length… of flag values means you can’t use normal “=” comparison operator with them: mysql> select count(*) from cbool where c1=NULL; +———-+ | count(*) | +———-+ | 0 | +———-+ 1…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… read_buffer_size selection may be less than obvious. What do we generally hear … high value. Sample my.cnf values on large memory sizes recommend 1M settings and MySQL…MySQL 5.1.21-beta was used for tests. mysql> select count(*) from dt2 where slack like “a%”; +———-+ | count(*) | +———-+ |…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
…with simple queries memory consumption is often less than 1MB per thread with default buffers, …of rarely considered MySQL Server Memory Requirements Thread buffers can be allocated more than once for…t relay on global values if developers may use their local values to run some … you might have counted…
