… NOT NULL can shift all values by a byte and thus will…to find indexes of the table. mysql> select * from SYS_TABLES WHERE NAME=’sakila/actor’; +————–+—–+——–+——+——–+———+————–+——-+ | … 2. Split ibdata1 with page_parser ./page_parser -f /var/lib/mysql/ibdata1…
Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
…=true: When the quorum algorithm fails to select a Primary Component, we have then a split-brain condition. In our 2 nodes… is gone: percona1 mysql> insert into percona values (0,’percona1′,’jaime’); Query OK, 1 row affected (0.02 sec) percona1 mysql> select * from percona….00 sec) percona2 mysql> insert into percona values (0,’percona2′,’daniel’); Query OK, 1 row affected (0.02 sec) percona2 mysql> select * from percona…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…onto the hot area, defeating the split. In order to prevent this from …mysql> select * from information_schema.global_status where variable_name like ‘%innodb%read%’; +—————————————+—————-+ | VARIABLE_NAME | VARIABLE_VALUE | …
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… this variable to some high value. Sample my.cnf values on large memory sizes recommend 1M settings and MySQL built-in default is…, with 3 runs and averaged results. MySQL 5.1.21-beta was used for tests. mysql> select count(*) from dt2 where slack like… – 128K and 32M is again the worst value. This means it can’t be request split issues, at least not just that…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
…be taken into account. I start by splitting our document into a list of words:…as run by the native database interface (MySQL): mysql> select word, md5(word), md5(reverse(word)), count… KEY UPDATE `word`=VALUES(`word`), `md5(word)`=VALUES(`md5(word)`), `count(*)`=`count(*)` + VALUES(`count(*)`) All …
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… value, so range 1..100 selects about 1% of the table. The times for full table scan vs range scan by index: mysql> select count(pad) from large; +————+ | count(pad) | +————+ | 31457280 | +————+ 1 row in set (4 min 58.63 sec) mysql> select count(pad… will not help. Sometimes it is good idea to manually split query into several, run in parallel and aggregate result sets…
Post: Read/Write Splitting with PHP Webinar Questions Followup
January 23, 2013 By 4 Comments
… store such as Memcached or APC. Store in $_SESSION only values that are ephemeral and easily recreated. Anything that needs to…. Q: What about write splitting (updates,inserts) on multiple MySQL servers? Or is it possible to split only read queries (select etc.)? A: You can set up a pair of MySQL instances…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…relational algebra to its logical maximum conclusion, splitting a problem up into many small problems…which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s … flight_delayed` + VALUES(`sum(DepDelay >= 0) flight_delayed`) — SQL TO SEND TO SHARDS Array ( [0] => SELECT origin…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
… bit instances. MySQL will fail to start on a micro instance, simply decrease the values in …test machine. It is possible to distribute splitting and/or loading among multiple nodes as … exec time, the third parse time). $ echo “select count(*) from ontime_fact;” | ./run_query Array ( [count(*)] =>…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…how to do read-write splitting without breaking the user …in mysql> show global variables like ‘%table_size%’; +———————+———–+ | Variable_name | Value | +———————+———–+ | max_heap_table_… EXPLAIN if possible (rewriting non-SELECT queries if needed, and …
