Thanks. To try and illustrate a little more - I have users creating ad-hoc SQL that provides the data they want, but may not be written optimally. I'd like to be able to use Calcite in some form to accept a SQL string from them and return an improved / optimised SQL string.
For my use case, calcite can have a live connection to the DBMS to get schema information and and other metadata it needs for optimization purposes. However I would like for it to avoid the normal final step of actually executing the user's query to fetch data. Hopefully that explains the goal / context better, but if not please let me know. Regards Andrew On Thu, 18 Apr 2019, 05:34 Yuzhao Chen, <[email protected]> wrote: > Andrew, I’m not very sure if I got your idea right. > > Do you want a promoted `Sql` compared to the original ? Then you should > transform Calcite’s RelNodes tree to sql, but Calcite do not support this > yet, The SqlNode unparse to sql is actually supported. > > It is not that equivalent for RelNodes tree and sql text, e.g. How to > describe a SemiJoin in sql ? Another question is the pure text to data > source will actually have another planning phrase, we can not make sure > this plan is the best and efficient. > > Best, > Danny Chan > 在 2019年4月18日 +0800 AM5:22，Andrew O <[email protected]>，写道： > > I'm interested in using Calcite in a "no execute" mode that would > > effectively return the optimized SQL but not actually execute it. The > > intention would be to leverage a) the query planning / optimization b) > the > > support for outputting different SQL dialects. > > > > I can see some Tests (e.g. JdbcTest.java) use CalciteAssert and that it > has > > a check "planHasSql" function. This seems to use a Hook to capture the > sql > > as part of the execution flow, so is not quite what I'm trying to do. > > > > I appreciate Calcite attempts to provide abstractions for different > > execution layers to allow cross adaptor function, so in theory a single > SQL > > statement may not always be available. However in my context I know it > > will be executing only against a single JDBC source and not other types. > > > > Is there any suggested / recommended approaches to this, or pointers to > > bits of code to look at? > > > > Thanks in advance > > > > Andrew >
