… | 1…many…big tables with no WHERE clause, or a WHERE clause on a non-indexed column. They also provide big improvement in query…or BKA when you are joining a really small…
Post: Shard-Query adds parallelism to queries
November 15, 2010 By 18 Comments
… a workload consisting of a small number of concurrent queries (or only one) to demonstrate…workerNo Shard-Query16 worker24 worker32 worker.1 year4.5481.0440.8540.8524.5484452247621…query into something more like OLTP. Instead of getting one big chunk of data in one query, it runs many smaller queries…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
… | 1.2.10 | | INNODB_BUFFER_POOL_INSTANCES | 1 | 8 | | QUERY_CACHE_SIZE | 0 | 1048576 | | SLOW_QUERY_… 2M. This change should help many small sorts for which allocation of …big change and is good one. We have been running innodb_file_per_table=1… large number of tables or if you do many create/drop of …
Post: How to load large files safely into InnoDB with LOAD DATA INFILE
July 3, 2008 By 29 Comments
… were many small files, which avoided splitting the file and let us load with many …gets bloated and slow. Even simple SELECT queries might have to scan through lots … it in one big 4.1GB transaction, then I did it 1 million rows at …). The single-file load showed about 1 or 2 percent higher I/O wait,…
Post: Fighting MySQL Replication Lag
September 22, 2008 By 7 Comments
…long running write query it clogs replication stream and small and …one big chunk which can’t be interleaved by any other query…1 WHERE id IN (list of ids) If there could be many ids matched on the first place you should also use query… save massive hardware purchases or development efforts based on …
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
…_at_trx_commit = 1 innodb_lock_wait_timeout …small sorts it is indeed better to have smaller sort buffer because allocating it will likely be faster. query_cache_size = 0M – query cache disabled. Not a big… a bit slower or faster but it…slower – it has many nice features …
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… you upgraded from MySQL 5.1 to Percona Server 5.5 and instead of …complicated test which runs this query concurrently many times or even workload consisting of several query types. Though it is…using hints such as STRAIGHT_JOIN, FORCE INDEX, BIG_RESULT/SMALL_RESULT. Check whatever stats are the same …
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… at databases Many people assume their application is difficult or somehow different,…commands. For example, ‘top -n 1‘ and ‘uptime’. That shows me … be fixed and bring big gains. Schema, query, and index optimization Analyzing…, frequent feedback lets us make small adjustments to the direction we’…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
… variance in the load and many things can be happening concurrently. … when some heavy queries are ran in background or backup is done with …small.PRIMARY 216.31397057 test.md_cache_test_small.k 2.66948509 test.md_cache_test_big…=1000 which will correspond to 1 sec. Separate Sysbench gives about …
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
…should be as low as possible, no more than 1:100″ or “your key cache hit ratio should be …are so small. The second server has been online practically forever, and that’s why its counters are big. Let…know it causes a great many Key_reads to occur. How much of this query‘s execution time is consumed…
