June 19, 2013

Post: How to find MySQL queries worth optimizing ?

… analyses as there are many possible ways query can be optimized. There is however one extremely helpful metric which you can… count(*) from sbtest group by k; This only sends 2 rows while scanning 10 million, while we can’t really optimize this… or no” answer but rather helps to understand how much optimization is possible. For example I might have query which uses…

Post: Four ways to optimize paginated displays

…) or b) execute a separate SELECT to count the rows. There are ways to optimize so you don’t have to do… we work on. Beyond indexing, re-organizing data, or query optimizations, there are two big things you can do. One is… list. With that in mind, here are four suggestions for optimizing paginated displays that can give significantly better performance. On the…

Post: Database access Optimization in Web Applications.

This is pretty simple approach I often use called to optimize web application performance if problem happens with few pages. If… remember avoiding accessing database is the best way you can optimize database access. This applies to anything else – if you can… of rows are analyzed by the query. For example SELECT COUNT(*) FROM links WHERE domain = ‘mysql.com’; will return only one…

Post: Getting around optimizer limitations with an IN() list

…Using where | +—-+————-+————-+——-+—————+———–+———+——+——+————-+ 1 row in set (0.01 sec) SELECT count(*) FROM coordinates FORCE INDEX (x_y_col_a) WHERE…this is simply a missing feature of the MySQL optimizer – and it has to do with using x …

Post: MySQL: what read_buffer_size value is optimal ?

The more I work with MySQL Performance Optimization and Optimization for other applications the better I understand I have to …-beta was used for tests. mysql> select count(*) from dt2 where slack like “a%”; +———-+ | count(*) | +———-+ | 4705992 | +———-+ 1 row in set (51.77…

Post: Why do you need many apache children ?

… to become serious problem. Depending on application and hardware this “optimal” number can be different and it is best to find…_CPUs+Num_disks), sometimes less sometimes more. With optimal concurrency you get optimal throughput, which is number of transactions per second. In…. Sometimes I see people to use the following formula to count optimal number of children – I have Page generated in 1.0…

Post: Optimizing slow web pages with mk-query-digest

…45 # Attribute pct total min max avg 95% stddev median # ============ === ======= ======= ======= ======= ======= ======= ======= # Count 0 519 # Exec time 2 148s 11us 33s 285ms 53ms…then even better than that would be if it would optimize the queries all together! Unfortunately mk-query-digest won’t…

Post: Sphinx search performance optimization: multi-threaded search

… some CPU-intensive operations such as ranking, ordering or even COUNT with GROUP BY and if data nodes return large amounts…

Post: Finding an optimal balance of I/O, CPU, and RAM for MySQL

… recently benchmarked the effects of increasing memory and CPU core count. He looked for a balance between utilizing the hardware as…

Post: Distributed Set Processing with Shard-Query

… node result set merge optimization enabled: ON DUPLICATE KEY UPDATE `origin_airport_id`=VALUES(`origin_airport_id`), `count(*)`=`count(*)` + VALUES(`count(*)`), `sum(AirTime)`=`sum… BY NULL ) — AGGREGATION SQL: SELECT `origin_airport_id`, SUM(`count(*)`) AS `count(*)`, SUM(`sum(AirTime)`) AS `sum(AirTime)`, SUM(`sum(DepDelay)`) AS…