Hi,
I am trying to use calcite as a library/abstraction layer to front several
DB backends and route queries to the backend best suited for the query.
For example for a table in hive if a subset of columns referenced in a
query have been replicated in postgres we will reroute the query to
postgres (and having it execute there)
(Note this is different than having calcite directly connect to postgres
and push down / do stuff in memory) - In our case complete execution is
delegated to the backend engine itself.
My schema is roughly similar to the following
{
"version": "1.0",
"defaultSchema": "hive",
"schemas": [
{
"type": "jdbc",
"name": "hive",
*//hive stuff is here*
},
{
"name":"postgres",
"materializations":[
{
"table":"bar",
"sql":""
}
]
}
]
This helps us route queries of the form select * from hive.table to
--> select * from postgres.bar.
I was reading the code in MaterializationTest.java (unit test), The way
this is currently done is through a jdbc:calcite connection (at connection
time the materializations are defined) and at query execution time the
materialized view gets used and substituted in the relnode tree. However
the code seems tightly coupled to the jdbc calcite call.
Is there any other way to get a relnode from a sql directly , call optimize
on it to do the MV substitution and return the rewritten query (and avoid
the jdbc call altogether)
(I plugged some code using RelToSqlConverter in the main codepath, and I am
able to log the rewritten query but can't think of a good way to return the
rewritten query directly bypassing the jdbc call. In my case the result of
execution of the query is going to be the rewrite of the query itself.
I went through the dev list but wasn't able to locate a way (also checked
out Qubole's Quark which does something similar although in a different
way). Any pointers would be really helpful. Apologies if this is a really
basic question
Thanks
Anupam
