… + 234M * (12 + 7) * 1.5 for fragmented secondary index + 234M * (12 + 20) * 1.5 for fragmented sbtest_r10 I assume: * 20 bytes… * 7 bytes per-row metadata overhead for secondary index entries * fragmented pages are 2/3 full So my guess is: * 50G…
Post: Keynotes, BOFs, and the Community Networking Reception at Percona Live MySQL Conference and Expo
April 15, 2013 By 1 Comment
… to accelerate that trend. The MySQL ecosystem is far from fragmenting, but 451 Research’s updated survey of database users indicates…
Post: Memory allocators: MySQL performance improvements in Percona Server 5.5.30-30.2
April 15, 2013 By
… creates requested block(s) there. That optimization helps to avoid fragmentation in case of many small allocations and allows to free…
Post: Learning about MySQL Table Fragmentation
May 1, 2008 By 20 Comments
… poor sequential scan performance even if table is not logically fragmented and Innodb is reading data in large blocks – this can… 300MB/sec which confirmed file fragmentation is also the issue. Interesting enough the “cure” for both fragmentation issues is the same – OPTIMIZE… would be cool to get Innodb objects (data and Index) fragmentation statistics which actually should not be that hard to implement.
Post: InnoDB: look after fragmentation
November 5, 2009 By 12 Comments
… dump in primary key order. So notes to highlight: InnoDB fragmentation may hurt your query significantly, especially when data is not in buffer_pool and execution goes to read from disk Fragmentation by secondary key is much more likely than by primary… by secondary key To check if you query affected by fragmentation you can use Innodb_scan_pages_contiguous ; Innodb_scan_pages…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
… is what I found: The fragmentation we speak in this article is filesystem fragmentation or internal table fragmentation which affects performance of full… from these results – Concurrent growth of many tables causes data fragmentation and affects table scan performance nadly – MyISAM suffers worse than…
Post: Working with many files and file system fragmentation
March 18, 2008 By 11 Comments
… like it does not do very good job preventing file fragmentation for large amount of growing files. It would be interesting… tables in some chunks (say 1MB) so its gets less fragmentation. Though it would be interesting to benchmark how much such approach would generally help. Until we have this feature – reduced fragmentation is one more benefit we get with batching. For example…
Post: Pretty-formatted index fragmentation with xtrabackup
March 15, 2011 By 4 Comments
… formats the stats output nicely to give an overview of fragmentation. It’s an initial draft, and if you find issues…
Comment: Air traffic queries in MyISAM and Tokutek (TokuDB)
November 6, 2009 By 26 Comments
… MyISAM runs, the worse the fragmentation becomes. In contrast, trickle-loaded TokuDB indexes exhibit no more fragmentation than bulk-loaded indexes. I…, incremental insertions are slow and produce fragmented indexes. TokuDB can handle the worst-case insertions without fragmentation or aging. Saying that B…
Comment: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
Siddhartha, one of the reasons for external fragmentation (file system fragmentation, which you can check with filefrag on ext2/3(/4)? … writing other files in the same partition). As for internal fragmentation, if you are modifying variable length data and/or there’s a decent rate of deletes and inserts, fragmentation is bound to occur regardless of the column type as…
