Yevgeny Zaspitsky has posted comments on this change. Change subject: db: aggregate qos and storage qos impl ......................................................................
Patch Set 6: (1 comment) Index on qos_type only is a wrong DB design http://gerrit.ovirt.org/#/c/27094/6/packaging/dbscripts/upgrade/03_05_0330_qos_and_storage_impl.sql File packaging/dbscripts/upgrade/03_05_0330_qos_and_storage_impl.sql: Line 27: -- add index on storage_pool_id Line 28: CREATE INDEX IDX_qos_storage_pool_id ON qos (storage_pool_id); Line 29: Line 30: -- add index on qos_type Line 31: CREATE INDEX IDX_qos_type ON qos (qos_type); > I don't even think that the DB will build a index for this table; moreover 1. Kobi, thank you for letting me learning something. 2. Merging 2 range scans isn't an optimization, but a severe performance degradation comparing to accessing a table through a single index composed of 2 columns. 3. I agree with Moti, we should add an index when we know that it would be used by a query, otherwise it will have an impact on insert performance. 4. Index on qos_type only will have very low cardinality and as such won't be effective. 5. "DB will build a index for this table" - it never does that if you don't tell it to do so. -- To view, visit http://gerrit.ovirt.org/27094 To unsubscribe, visit http://gerrit.ovirt.org/settings Gerrit-MessageType: comment Gerrit-Change-Id: I1a9af59277b5055453159f002f19046c0051d63b Gerrit-PatchSet: 6 Gerrit-Project: ovirt-engine Gerrit-Branch: master Gerrit-Owner: Gilad Chaplik <[email protected]> Gerrit-Reviewer: Allon Mureinik <[email protected]> Gerrit-Reviewer: Doron Fediuck <[email protected]> Gerrit-Reviewer: Eli Mesika <[email protected]> Gerrit-Reviewer: Gilad Chaplik <[email protected]> Gerrit-Reviewer: Kobi Ianko <[email protected]> Gerrit-Reviewer: Liron Ar <[email protected]> Gerrit-Reviewer: Yair Zaslavsky <[email protected]> Gerrit-Reviewer: Yevgeny Zaspitsky <[email protected]> Gerrit-Reviewer: [email protected] Gerrit-Reviewer: oVirt Jenkins CI Server Gerrit-HasComments: Yes _______________________________________________ Engine-patches mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/engine-patches
