Wrong typing, it is DML not DDL ~~~😅 guo Maxwell <cclive1...@gmail.com> 于2024年12月23日周一 11:56写道：
> Thanks Caleb for bringing it up. > > When I opened this issue, I originally wanted to propose the following > syntax: > 1、When we want to force the selection of certain indexes: > SELECT ...USE INDEX (ks.idx1, ks.idx2....) ... FROM ...WHERE ... > or > SELECT .../*+ USE INDEX (ks.idx1, ks.idx2....)*/ ... FROM ...WHERE ... > > 2、When we want to ignore the selection of some indexes: > SELECT ...IGNORE INDEX (ks.idx1, ks.idx2....) ... FROM ... WHERE ... > or > SELECT .../*+ IGNORE INDEX (ks.idx1, ks.idx2....) */ ... FROM ... WHERE > ... > > And In fact, what I originally wanted to do was to provide a hint function > <https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html#optimizer-hints-overview> > similar to MySQL, which can push down some rules dynamically. > The work to provide a hint for DDL needs to be accomplished in many steps, > CASSANDRA-18112 for index hint is part of it, maybe the first step. > > > Ekaterina Dimitrova <e.dimitr...@gmail.com> 于2024年12月21日周六 22:27写道： > >> Naming is hard but to me providing what Caleb mentioned through something >> like WITH OPTIONS sounds reasonable. Thanks for bringing it up. >> >> On Sat, 21 Dec 2024 at 2:46, Joel Shepherd <sheph...@amazon.com> wrote: >> >>> WITH INDEX (or something equivalent) seems really useful. >>> >>> Less opinionated on the specific syntax, but I think there is a lot of >>> value in the form of predictable, controllable performance, in giving >>> developers more direct control over query execution, whether that's >>> index selection or even lower-level decisions. If you've experienced the >>> thrill of operating a database with a cost-based planner that abruptly >>> selects a new, sub-optimal plan due to a change in statistics or >>> configuration, you'll appreciate language features that yield some >>> planning control back to you. It does increase the burden on the >>> developer to understand how best to execute the query, but it makes >>> their intent much more obvious, and easier to adjust as the system >>> changes. >>> >>> -- Joel. >>> >>> On 12/20/2024 12:28 PM, Caleb Rackliffe wrote: >>> > Some of your are probably familiar with work in the DS fork to improve >>> > the selection of indexes for SAI queries in >>> > >>> https://github.com/datastax/cassandra/commit/eeb33dd62b9b74ecf818a263fd73dbe6714b0df0#diff-2830028723b7f4af5ec7450fae2c206aeefa5a2c3455eff6f4a0734a85cb5424. >>> >>> > >>> > >>> > While I'm eagerly anticipating working on that in the new year, I'm >>> > also wondering whether we think some simple CQL extensions to manually >>> > control index selection would be helpful. Maxwell proposed this a >>> > while back in CASSANDRA-18112, and I'd like to propose a syntax: >>> > >>> > >>> > ex. Do not use the specified index during the query. >>> > >>> > SELECT ... FROM ... WHERE ... WITHOUT INDEX <ks.idx> >>> > >>> > This could be helpful for intersection queries where one of the >>> > provided clauses is not very selective and could simply be handled via >>> > post-filtering. >>> > >>> > ex. Require the specified index to be used. >>> > >>> > SELECT ... FROM ... WHERE ... WITH INDEX <ks.idx> >>> > >>> > This could be helpful in scenarios where multiple indexes exist on a >>> > column and was the primary motivation for CASSANDRA-18112. >>> > >>> > Thoughts? >>> >>
