…: sql/log.cc, MYSQL_QUERY_LOG::write(): 1945 /* For slow query log */ 1946 sprintf(query_time_buff, “%.6f”, ulonglong2double(query_utime)/1000000.0); 1947 sprintf… most frequent queries, even if the response time is so imprecise. But pt-query-digest and similar tools don’t read the query log…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
… tried to improve the response time of their top slow query according to pt-query-digest’s report. This query was run very frequently and… | | freeing items | 0.000035 | | logging slow query | 0.000004 | | cleaning up | 0.000005 | +———————-+———-+ So the unstable response times did not come from a…
Post: Optimizing slow web pages with mk-query-digest
April 7, 2011 By 14 Comments
… – I had a slow query log (captured with long_query_time=0 and all the eXtra benefits from Percona slow query log patch), I knew… impact to this page response time. I can also convert that into a slow query log that lists all the queries that were executed during this session in the order they were executed: mk-query-digest…
Post: What do we optimize with mk-query-digest ?
December 15, 2009 By 2 Comments
… to query itself – general system overload, row level locks, table locks all could cause query response time to be unreasonable. If Slowest query is not interactive query, for example part of a… responsible for large portion of response time without any slow queries. We’ve seen pages which take 10.000, 20.000 and even more queries…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… have enabled slow query logging and set a low enough value for long_query_time. We normally use a value of long_query_time… pt-query-digest Using pt-query-digest is pretty straight forward: pt-query-digest /path/to/slow-query.log Note that executing pt-query-digest can… next part of the output produced by pt-query-digest. # Profile # Rank Query ID Response time Calls R/Call Apdx V/M Item…
Post: Gathering queries from a server with Maatkit and tcpdump
July 1, 2009 By 23 Comments
… of the protocol. This lets us gather queries from servers that don’t have a slow query log enabled, at very high time resolution. With this new functionality, it becomes possible for mk-query-digest to… it. Let’s see: mk-query-digest –type=tcpdump –report-format=profile tcpdump.out # Rank Query ID Response time Calls R/Call Item…
Post: On Good Instrumentation
May 31, 2010 By 1 Comment
… of queries or their performance. If I see 2 queries taking 30 seconds it is clearly slow queries. If it is 10.000 queries executed and total response time is 4… increased response time for given kind of request. I see response time is coming from MySQL. I check the number of MySQL Queries…
Post: How to use tcpdump on very busy hosts
April 18, 2011 By 17 Comments
… a situation where a single connection sends two queries and gets two responses, with a response time of R for each request, and… mk-query-digest output was obviously bogus when compared to the host’s slow-query-log (for example, none of the top 5 slow queries reported by mkqd appeared in the actual slow log file…
Post: Percona Server 5.1.53-12.4
December 29, 2010 By Leave a Comment
… variable have_response_time_distribution and compile option –without-response_time_distribution in Response Time Distribution. (Oleg Tsarev) Bugs Fixed Bug #643149 – Slow query log… crash or undefined behavior: log_slow_timestamp_every, log_slow_sp_statements, slow_query_log_microseconds_timestamp, use_global_long_query_time. (Oleg Tsarev) Bug…
Post: Percona Server with XtraDB Case Study, Behind the Scenes
October 21, 2010 By 13 Comments
… of slow queries I found was caused by different things. Sometimes GDB stack traces showed InnoDB mutex contention, sometimes oprofile showed the query… response times were from data I gathered with tcprstat. I also used the data from tcprstat to analyze the variation in query response… ad-hoc slow-query-log analysis with awk and other tools to discover and investigate unusual patterns, and figure out whether queries were…
