…the table, but how long will this take? Is there a facility we can run to show any table / index fragmentation, without having to run the OPTIMIZE? HT: Since OPTIMIZE rebuilds the whole table, it may last way too long for your 150 GB table! If…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
…the query cache as it was enabled. Contention on the query cache mutex when checking if the result set can be served from the…the fragmentation of the cache and degrade performance for other queries. The best solution was simply to turn off the query cache. Conclusions: Once again, the…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
…The fragmentation we speak in this article is filesystem fragmentation or internal table fragmentation which affects performance of full table scan. Not all queries are going to…tables we had just 1000 of 4K rows in the table which caused too much space allocated as single pages. I expect if…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
…if having more secondary indexes in the table…fragmentation. Fast index creation results in much less fragmented indexes because records are inserted in the…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
…if it is really best strategy: To check things out I’ve created table with simple structure: mysql> show create table dt2 \G *************************** 1. row *************************** Table…
Post: InnoDB: look after fragmentation
November 5, 2009 By 12 Comments
…to figure out what’s going on. So let me introduce problem at first. The table is CREATE TABLE…The problem is that after restoring table from mysqldump, the query that scans data by primary key was slow. How slow ? Let me show. The…secondary key To check if you query affected by fragmentation you can …
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…to retrieve data from table. Avoid comment (and space) in the start of the query – Query Cache does simple optimization to check if…to identify if you have enough memory for query cache. Note however due to fragmentation lowmem_prunes can be triggered even if…
Post: Falcon Storage Engine Design Review
January 12, 2007 By 19 Comments
…the release we tested it is hard to see how small indexes really are. [-] No “using index” Falcon always have to check the row data even if… can help a lot if you traverse significant portion of the table (or data …regarding handling fragmentation – what happens on row updates, are they stored in the …
Page: Tools
May 30, 2008 By 31 Comments
…tables. Very nice to watch what happens to server in the real time. filefrag filefrag is the fool to check fragmentation of the file. Ever wondered how fragmented your tablespace or table…
Post: Make your file system error resilient
August 24, 2011 By 8 Comments
…Fragment size: 4096 Reserved GDT blocks: 316 Blocks per group: 32768 Fragments…to check file systems. I believe it is much better to disable both these auto check functions for your data partition and just check…
