… + 20) for PK index + 234M * (12 + 7) * 1.5 for fragmented secondary index + 234M * (12 + 20) * 1.5 for fragmented sbtest_r10 I assume… index pages are 15/16 full as they are loaded in order * 7 bytes per-row metadata overhead for secondary index entries * fragmented pages are 2/3 full So my guess is: * 50G for PK index * 6G for secondary index on base…
Post: Learning about MySQL Table Fragmentation
May 1, 2008 By 20 Comments
… clause may pick to scan some small index instead. If your table is not fragmented one of two things should happen – either… 300MB/sec which confirmed file fragmentation is also the issue. Interesting enough the “cure” for both fragmentation issues is the same – OPTIMIZE… key but not the index. P.S It would be cool to get Innodb objects (data and Index) fragmentation statistics which actually should…
Post: Pretty-formatted index fragmentation with xtrabackup
March 15, 2011 By 4 Comments
…) has support for printing out stats on InnoDB tables and indexes. This can be useful to examine whether you’d benefit… formats the stats output nicely to give an overview of fragmentation. It’s an initial draft, and if you find issues… of the code listing. The output looks like this: TABLE INDEX TOT_PAGES FREE_PAGES PCT_FULL art.link_out104 832383…
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… FAST INDEX creation) so be careful with queries scan many records by secondary key To check if you query affected by fragmentation…
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… contrary to my expectation this filesystem was created without dir_index option which should add significant overhead for insert with many…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
… the execution time is proportional to the number of indexes, with fast index creation the time required to copy the data to… the indexes will obviously take longer. Another important thing that is worth mentioning is fragmentation. Fast index creation results in much less fragmented indexes because…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… there a facility we can run to show any table / index fragmentation, without having to run the OPTIMIZE? HT: Since OPTIMIZE rebuilds… table scan would be fast. Maybe the table has become fragmented? Or maybe you have not inserted in the ascending order…, primary key equality searches should work through the adaptive hash index! What is your database like? Do you have a big…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
… one have optimized indexes and sorting in such a scenario, since inequality ends index usage. Actually in this case index on (A,B… can slow down your inserts and make primary key significantly fragmented. I also would note there are some MySQL optimizer restrictions…: We have a database that has about 400GB of indexes. The indexes can’t fit in memory anymore. How does this affect…
Comment: Heikki Tuuri to answer your in depth Innodb questions
October 2, 2007 By 51 Comments
… there a facility we can run to show any table / index fragmentation, without having to run the OPTIMIZE?
Comment: Air traffic queries in MyISAM and Tokutek (TokuDB)
November 6, 2009 By 26 Comments
… bulk load, the MyISAM indexes are not fragmented. That makes the MyISAM indexes nearly as good as the TokuDB indexes. If you were to… runs, the worse the fragmentation becomes. In contrast, trickle-loaded TokuDB indexes exhibit no more fragmentation than bulk-loaded indexes. I haven’t seen…
