… in the list, while it could be done only by reading data from the index. MySQL can ether read index only for all rows, in this case you will see “Using Index” in EXPLAIN output or… this point. So MySQL Will not use indexes in all cases when it is technically possible. For multiple key part indexes MySQL will only be…
Post: Descending indexing and loose index scan
May 9, 2006 By 6 Comments
…) to keep index smaller. The good news are Loose index scan implementation is finally on a way. In fact it was even implemented in MySQL 5.0, but only for very narrow case of aggregate queries. In general complete loose index scan implementation…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 12 Comments
…an article about using UNION to implement loose index scan. First I should mention double IN also works same way so … 1 row in set (0.00 sec) So as you see there are really different types of ranges in MySQL. IN range …
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
…, location; integer – age 3) All queries fall into X IN (…) AND Y IN (…) AND … Some conditions fall into X = const – ref access… about index_merge_intersection, we should understand that mysql finds one set using an index, another set and then finds records which exist in…/10/using-union-to-implement-loose-index-scan-to-mysql/#comment-1695 2. http://dev.mysql.com/doc/refman/5.1/en/index-merge-intersection.html
Post: Guidance for MySQL Optimizer Developers
September 20, 2009 By 4 Comments
… full table scan when Index access is better or because MySQL simply does not have execution method to resolve query in optimal way – loose index scan, hash join, sort merge join are all the examples of such. For me it is most important to ensure MySQL has…
Post: Database problems in MySQL/PHP Applications
August 11, 2006 By 12 Comments
…these problems with loosing data etc. Read more in my Why MySQL Could be …in MySQL you might be better of using several queries than doing complicated ones. Of course you would rather use IN…indexing missing which requires queries to do full table scans. Funny enough this is often not the problem in…
Comment: My Innodb Feature wishes
May 9, 2006 By 30 Comments
… descending indexes and about loose index scan, or what Gokhan calls “better range” support. None of these are actially related to Innodb tables in general – these are features MySQL…
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 12 Comments
… problems with loosing data etc. Read more in my > Why MySQL Could …in MySQL you might be > better of using several queries than doing complicated ones. Of > course you would rather use IN…indexing missing which > requires queries to do full table scans. Funny enough this is often > not the problem in…
