…. Not only such connection related allocations are invisible but many global allocations are poorly visible too. Sure, we know how much…” etc. For global pools we need just global accounting, for connection basics accounting should be done per connection but aggregated globally. This way… performance bottleneck such profiling will help to find a lot of wasteful memory allocation and help to get MySQL on the memory…
Post: Announcing Percona Server 5.5.25a-27.1
July 21, 2012 By Leave a Comment
…profiling. This was implemented because with process based profiling, threads on the server, other than the one being profiled, can affect the profiling… (Ignacio Nin). Querying I_S.GLOBAL_TEMPORARY_TABLES or TEMPORARY_TABLES… #988383 (Stewart Smith). Fixed upstream mysql bug #60743, typo in cmake…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… disk versus how many page requests their were: mysql> select * from information_schema.global_status where variable_name like ‘%innodb%read%’; +—————————————+—————-+ | VARIABLE…_blocks_time=0; mysql> set global innodb_old_blocks_time=0; Query OK, 0 rows affected (0.00 sec) mysql> select straight_join… row in set (0.00 sec) Finally, I collected SHOW PROFILES information for the faster join direction (fact -> dimension) select p1…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
… how you can profile queries to see what exactly happens during query execution – very helpful for MySQL Performance optimization: mysql> flush status; Query OK, 0 rows affected (0.00 sec) mysql> SELECT sql_no_cache… will show per session counter increments and to get global counters SHOW GLOBAL STATUS needs to be used. Let us look at…
Post: Wanted: Better memory profiling for MySQL
May 18, 2008 By 4 Comments
… memory. It was long spoken about global resource management for MySQL, ie so I could restrict global temporary space for temporary tables or… of memory allocated for current thread in addition to global memory allocation. As MySQL is progressing the problem of memory allocation transparency…
Comment: Solving INFORMATION_SCHEMA slowness
December 25, 2011 By 25 Comments
…) mysql> set global innodb_stats_on_metadata=0; Query OK, 0 rows affected (0.00 sec) mysql… | 276 rows in set (0.00 sec) mysql> show profile for query 14; +———————-+———-+ +———————-+———-+ +———————-+———-+ | Status | Duration | | removing …
Post: Query Profiling with MySQL: Bypassing caches
September 12, 2007 By 6 Comments
… engines have similar buffers. There is also table_cache both MySQL side and Internal Innodb one which can affect query execution…. So How can you bypass these caches? For MySQL Caches you can restart MySQL and this is the only way to clean… clean MySQL table cache (but not Innodb table meta data) or you can do “set global key_buffer_size=0; set global key…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…and Created_disk_tmp_tables, I’ll paste in mysql> show global variables like ‘%table_size%’; +———————+———–+ | Variable_name | Value | +———————+———–+ | …be really significant, and can completely change the performance profile and workload of a server, so it’s …
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
… you can get from SHOW GLOBAL STATUS. I’ll start out by copying and pasting from the MySQL manual: Key_read_requestsThe… slow and is a problem for my application. I have profiled it with SHOW STATUS and I know it causes a… and compare the results to your IO system’s capabilities. MySQL doesn’t have good instrumentation for scientifically choosing a key…
Post: Read Buffers, mmap, malloc and MySQL Performance
September 12, 2007 By 8 Comments
… not something you would expect right ? me too. Not only global user data is expected to be cached on startup but… see from this post is – o_profile (often together with strace) are great tools for MySQL Performance analyses. Too many people end… you could just grab one having allocation very quick. Also MySQL should get smarter in terms of which buffer size should…
