Hi Ian, The task was mainly to set a value greater than 0. So on the optimizer call it was decided that we can raise it to 200 too. I will do it in a new patch.
On Sat 2 Feb, 2019, 12:36 AM Ian Gilfillan <i...@mariadb.org wrote: > I see the eq_range_index_dive_limit default has been set to 10 in > 10.4.3. I see some different EXPLAIN results in the commit, but I don't > see any notes on why or how 10 was chosen over any other value. MySQL > increased the default to 200 from MySQL 5.7.4, based it seems on some > community feedback that 10 was too low, for example: > > https://www.facebook.com/notes/mysql-at-facebook/eq_range_index_dive_limit-system-variable-in-mysql-56/10151533648715933. > > What was the thinking behind choosing 10 as the new default? > > On 2018/10/12 12:58, Sergey Petrunia wrote: > > Hello, > > > > So, MDEV-16934 introduced eq_range_index_dives_limit into 10.2.8 and > 10.3.0. > > > > The default was set to 0 (which means no limit) in order to not introduce > > optimizer behavior change into stable versions. > > > > The question is: should 10.4 also have 0 by default or we can set it to > some > > finite limit? MySQL's default value is 10. > > > > BR > > Sergei > > > _______________________________________________ > Mailing list: https://launchpad.net/~maria-developers > Post to : maria-developers@lists.launchpad.net > Unsubscribe : https://launchpad.net/~maria-developers > More help : https://help.launchpad.net/ListHelp >
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