[Betternestedset-talk] MySQL performance with large tables
lindsaye at gmail.com
Thu Feb 15 22:32:46 EST 2007
Just joined the list, I checked through the archives & tickets, but
couldn't find anything similar.
I've recently started using better nested set on a project, and found
that the performance was rather horrible on an InnoDB table with ~2.2
million rows (~27 seconds on a self_and_ancestors call, set is about
5 levels deep)
After a bit of digging I discovered that MySQL was ignoring the
indexes I'd set on the lft & rgt columns when using the BETWEEN
According to the MySQL docs, between is equivalent to (min <= expr AND
expr <= max) <http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#operator_between>,
after replacing all the instances with this syntax, the query time
went down to ~0.5sec, quite an improvement :)
This has been working fine for me so far, but it would be great to
hear others opinions on whether this will cause any other problems.
I've attached a patch if anyone wants to check it out for themselves.
I haven't tested this very extensively apart from in my app, just ran
the unit tests & they all passed (after updating the test_sql_for to
use the same syntax).
I've also only tested this with MySQL 5, so I have no idea how these
changes would effect other databases.
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