…too much as there are few completely uncached workloads but 100+ times difference is quite frequent. Indexes What everyone knows about indexes is…tables being small it would not slow things down too much. On other hand join of few large tables, which is…
Post: My Innodb Feature wishes
May 4, 2006 By 30 Comments
… Heikki did good presentation about Innodb planned features. I did not …to be much faster as well as ALTER TABLE (expecially together with ability to create index without table rebuilding) Buffer…all and for certain workloads 16K is too much while for some others too little. Being able to specify page…
Post: Full table scan vs full index scan performance
November 23, 2012 By 15 Comments
… full table scan is not good for performance, how much can we expect if we can switch to a full index scan? In other terms, is a full table… when the index is covering. Don’t forget to measure response time when you are trying different execution plans. It is too easy to…
Post: Recovering Innodb table Corruption
July 4, 2008 By 22 Comments
…indexes, in which case simple OPTIMIZE TABLE could be enough to rebuild it, but it is much better compared to table…TABLE says table is OK. This means You Can’t Trust CHECK TABLE in Innodb to be sure your tables are good….tried to skip 30 rows and it was too little while skipping 80 rows was OK. Again…
Post: How (not) to find unused indexes
October 16, 2009 By 2 Comments
…indexes should be removed. This method is flawed – here’s the first reason why: CREATE TABLE…index is woeful, but provided that the application is always only sending query 1 to MySQL it’s actually a pretty good index… time it is searching in is too wide. Side …is not fixed in MySQL and can be a much…
Post: Learning about MySQL Table Fragmentation
May 1, 2008 By 20 Comments
… Innodb table fetched in memory as fast as possible to get good in …table scan – running count(*) without where clause may pick to scan some small index instead. If your table is…table=1) which normally would be much less fragmented because it is written at once. Too bad however it requires table…
Post: Hacking to make ALTER TABLE online for certain changes
October 29, 2007 By 26 Comments
… hours for table rebuild to complete. If you’re unlucky i.e. you have a lot of indexes and not too much RAM – you… tables take time to rebuild. Disclaimer: try this at your own risk. It worked for me, it may work for you too… that auto_increment is removed. I’ve been a bit surprised, that removing value from enum() works as good as adding it…
Comment: When should you store serialized objects in the database?
January 22, 2010 By 47 Comments
… is too much thought into whether the technique is a good or bad one and not focusing on when to use the serialized data in tables… separate database table with one other column indexed to map to another table. For example, have a table of accounts, make another table called account…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…index lookups and number of non-hash index lookups which is indication of hash index efficiency. There is currently not much…is also very good values to monitor and graph – row operations is very good…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…tables in this system. innodb_stats_on_metadata is disabled by default in MySQL 5.6 Welcome to much…is too small to be practical if someone tries to enable it. sql_mode has NO_ENGINE_SUBSTITUTION value by default which is good…
