…: Make the master read-only so that the slaves can execute all events and be in sync with the master Change… time, replication on slave #1 will stop: 2013-05-17 13:32:08 2563 [ERROR] Slave I/O: The slave IO thread… test.t (id int not null auto_increment primary key); Executing SHOW TABLES FROM test on both slaves shows that the…
Post: Why MySQL Performance at Low Concurrency is Important
March 27, 2013 By 8 Comments
… the best response times (MySQL server does not use multiple threads to execute query in parallel at this point). Response times at the variety… single-thread execution is what is going to happen — many batch jobs are written to be single-threaded. MySQL replication is single-thread too…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
…(aka QPS sysbench mode); same MySQL queries executed inside single-statement transactions (TPS mode, see… cpu threads) Cisco UCS C250 (12cores/24 cpu threads) Dell PowerEdge R720 (16 cores/32 cpu threads)… –rand-type=uniform –forced-shutdown=1 –max-time=120 –max-requests=0 –percentile=99 –mysql-…
Post: High-load problems? Investigate them with 'pt-query-digest'
April 23, 2013 By 2 Comments
…set up pt-stalk to trigger a capture if Threads_running went above a known ‘good’ value for …capture (under normal circumstances, this file will have –run-time snapshots separated by timestamps) and ran that by… query that ended up having a much better execution plan, but that is beyond the scope of …
Post: Galera Flow Control in Percona XtraDB Cluster for MySQL
May 2, 2013 By 5 Comments
…of some large transaction briefly stalling an applier thread. However, it is possible to halt queue …more expensive replication conflicts more likely and therefore time-consuming to the application. How to tell … I can easily see flow control if I execute a FLUSH TABLES WITH READ LOCK on node3:…
Post: Follow these basics when migrating to Percona XtraDB Cluster for MySQL
May 1, 2013 By 10 Comments
… data will remain consistent within the cluster. Also, at the time of this writing, from async stream, MyISAM is not being… If you still have tables without PRIMARY KEYs, then its time to make one for them. Galera does not work well… has an additional overhead, this means the SQL_THREAD will not be able to execute events as fast, on top of that…
Post: Query Response time histogram - new feature in Percona Server
July 11, 2010 By 11 Comments
… and which basically means that there were 7040 queries with execution time less than 1 sec and more than 0.1 sec… affects response time. There are histograms and pie charts for sysbench oltp runs for 1, 32 and 128 concurrent threads 1 thread time count… were executed with execution time in interval (0.1ms, 1 ms] and 86% queries had execution time in interval (0.01ms, 0.1ms] 32 threads time count…
Post: How to obtain the "LES" (Last Executed Statement) from an Optimized Core Dump?
September 9, 2012 By 9 Comments
…were testing a C program with three threads executing highly concurrent DML statements (where each thread executes one particular type of statement) and you…was at compilation time) First we inspect the mysql_execute_command frame: (gdb) frame 21 #21 0x00000000005a30af in mysql_execute_command (thd=…
Post: What time 18446744073709550.000 means
May 17, 2009 By 25 Comments
… and I noticed sysbench getting crazy showing query execution time 18446744073709550.000 or like this. Obviously this is …start_time = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &tp); … query_execution … end_time = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &tp); total_time = end_time – start_time…
Post: What is exec_time in binary logs?
January 31, 2011 By 2 Comments
… in the output: “exec_time=0″ What is the exec_time? It seems to be the query’s execution time, but it is not. In most cases, the exec_time will be similar to the query execution time on the… log_slave_updates on the replica. When the statement executes in the replication thread, it will be logged to the replica’s…
