In fact, parse twice's impact is little, in Apache Kylin, every time we do the transformation to SQL, we re-parse it. What really takes time is validation (use metadata like getting it from HMS) and optimization.
Regards! Aron Tao Juan Pan <panj...@apache.org> 于2020年11月22日周日 下午2:32写道： > Hi community, > > > > > Thanks for your attention. : ) > > > > > Currently, Apache ShardingSphere community plans to leverage Apache > Calcite to implement federated SQL query, > > i.e., the query from different database instances [1]. > > > > > The draft approach is that we consider using the custom adaptor with the > SQL parser of ShardingSphere itself (Antlr involved), > > and transforming the parsed result to the algebra of Calcite. > > Lastly, Calcite will execute the SQLs by means of the custom adaptor. > > > > > Currently, I know the entrance of calling the custom adaptor is to use the > `DriverManager.getConnection(CalciteUrl)`, which will get Calcite's SQL > parsing involved. > > But we want to avoid twice SQL parsing, which means we wish to ignore the > SQL parsing of CalciteN . > > > > > My question is that how we can leverage Calcite adaptor without using > Calcite parser. > > Could you give me some hints? > > > > > Very appreciated your any help and reply. > > > > > Regards, > > Trista > > > > > > > > [1] https://github.com/apache/shardingsphere/issues/8284 > > > > Juan Pan (Trista) > > Senior DBA & PMC of Apache ShardingSphere > E-mail: panj...@apache.org > > > >
