… 0 | | Handler_delete | 0 | | Handler_discover | 0 | | Handler_prepare | 0 | | Handler_read_first | 0 | | Handler_read_key | 1 | | Handler_read_next | 42250 | | Handler_read_prev | 0 | | Handler_read_rnd | 0 | | Handler_read_rnd_next | 0 | | Handler_rollback | 0 | | Handler_savepoint | 0 | | Handler…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
Comment: What does Handler_read_rnd mean?
June 25, 2010 By 15 Comments
…) mysql> show status like ‘Handler_read_rnd_next‘ ; +———————–+——-+ | Variable_name | Value | +———————–+——-+ | Handler_read_rnd_next | 4 | +———————–+——-+ 1 row in set (0.00 sec) Handler_read_rnd_next was not incremented the second…
Post: What does Handler_read_rnd mean?
June 15, 2010 By 15 Comments
… often confusing and result in “what does that mean?” questions: Handler_read_rnd Handler_read_rnd_next As I understand it, there is some historical context to… read a row based on a primary key value. Handler_read_rnd_next is incremented when handler::rnd_next() is called. This is basically a cursor operation: read the “next…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… 0 Handler_read_key 508833 623738 622184 508913 507516 Handler_read_next 574320 574320 572889 574320 572889 Handler_read_rnd_next 136077 136094 136366 136163 136435 Innodb_buffer_pool_read_ahead 0 20920 23669 20920 23734 Innodb_buffer_pool_read_requests…
Post: Joining on range? Wrong!
May 17, 2010 By 10 Comments
… detail: SHOW STATUS LIKE ‘Handler_read%’; +———————–+——–+ | Variable_name | Value | +———————–+——–+ | Handler_read_first | 0 | | Handler_read_key | 3 | | Handler_read_next | 118181 | | Handler_read_prev | 0 | | Handler_read_rnd | 0 | | Handler_read_rnd_next | 0…
Comment: What does Handler_read_rnd mean?
June 26, 2010 By 15 Comments
… SELECT. Scanning the copy the second time does not increment Handler_read_rnd_next. However, scanning the original mysql.user does. So it is… mystery that I do not understand, though, is how incrementing Handler_read_rnd_next is avoided on a MyISAM table without the query cache…
Comment: What does Handler_read_rnd mean?
June 23, 2010 By 15 Comments
…: | Handler_read_rnd | 5000 | | Handler_read_rnd_next | 10002 | | Handler_write | 5014 | So, essentially “scan 5000 rows, insert 5000 rows into temp table, sort them with a scan, read… extra 14 rows in Handler_write should be due to SHOW STATUS. SELECT user FROM user gives | Handler_read_rnd_next | 5001 | SELECT 1 FROM…
Comment: How to estimate query completion time in MySQL
April 22, 2008 By 16 Comments
… value of Handler_read_rnd_next and divide it by number of total threads connected (ever?) will that give us a reasonable row reads per second? When I ran “mysqladmin extended -r -i 10 | grep Handler_read_rnd_next” I got a value… good row reads per second or I am misled by the data. What should I read into when the value of Handler_read_rnd_next is…
Post: How to estimate query completion time in MySQL
April 22, 2008 By 16 Comments
… scan of the fact table. This is shown by the Handler_read_rnd_next status variable. Here’s an easy way to watch it… -r -i 10 | grep Handler_read_rnd_next — ignore the first line of output… | Handler_read_rnd_next | 429224 | So the server was reading roughly 43K rows per second…
Comment: How much memory can MySQL use in the worst case?
February 19, 2009 By 17 Comments
… few: Innodb_buffer_pool_reads 12 Handler_read_rnd 2,448 k(this increases steady as the server runs) Handler_read_rnd_next 105 M(this increases steady…
