Hi, Is there a way to force H2 to use an index > instead of another one (hint?)? >
Currently, there are not many ways to enforce one index is used. One way is to set the selectivity manually before running the query: alter table test alter column id selectivity 4; However, the selectivity will be re-evaluated from time to time (this can be disabled by appending ; ANALYZE_AUTO=0 to the database URL). Another workaround is to ensure the wrong index can't be used: ANALYZE SELECT COUNT(1) FROM endf_sections WHERE mat_key=5159 AND -mf=-3 AND (-mt=-4 OR -mt=-14) Support for hints is quite high on the priority list, I will implement it in one of the next releases. > How exactly is selectivity computed? In the H2 console, if we display > the first 10000 rows of this table, we obtain 139 distinct values > yielding a selectivity of 1 we presume; Is that correct? > Yes. Regards, Thomas -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/h2-database?hl=en.
