3 Commits (10603ed5d45ad435b3d3122146f67b7de95b4d06)

Author	SHA1	Message	Date
Sait Talha Nisanci	80d2bc2317	normalize some output and sort test result	2020-08-04 15:18:27 +03:00
Nils Dijk	a77ed9cd23	Refactor master query to be planned by postgres' planner (#3326) ... DESCRIPTION: Replace the query planner for the coordinator part with the postgres planner Closes #2761 Citus had a simple rule based planner for the query executed on the query coordinator. This planner grew over time with the addigion of SQL support till it was getting close to the functionality of the postgres planner. Except the code was brittle and its complexity rose which made it hard to add new SQL support. Given its resemblance with the postgres planner it was a long outstanding wish to replace our hand crafted planner with the well supported postgres planner. This patch replaces our planner with a call to postgres' planner. Due to the functionality of the postgres planner we needed to support both projections and filters/quals on the citus custom scan node. When a sort operation is planned above the custom scan it might require fields to be reordered in the custom scan before returning the tuple (projection). The postgres planner assumes every custom scan node implements projections. Because we controlled the plan that was created we prevented reordering in the custom scan and never had implemented it before. A same optimisation applies to having clauses that could have been where clauses. Instead of applying the filter as a having on the aggregate it will push it down into the plan which could reach a custom scan node. For both filters and projections we have implemented them when tuples are read from the tuple store. If no projections or filters are required it will directly return the tuple from the tuple store. Otherwise it will loop tuples from the tuple store through the filter and projection until a tuple is found and returned. Besides filters being pushed down a side effect of having quals that could have been a where clause is that a call to read intermediate result could be called before the first tuple is fetched from the custom scan. This failed because the intermediate result would only be pulled to the coordinator on the first tuple fetch. To overcome this problem we do run the distributed subplans now before we run the postgres executor. This ensures the intermediate result is present on the coordinator in time. We do account for total time instrumentation by removing the instrumentation before handing control to the psotgres executor and update the timings our self. For future SQL support it is enough to create a valid query structure for the part of the query to be executed on the query coordinating node. As a utility we do serialise and print the query at debug level4 for engineers to inspect what kind of query is being planned on the query coordinator.	2020-02-25 14:39:56 +01:00
Jelte Fennema	7abedc38b0	Support subqueries in HAVING (#3098) ... Areas for further optimization: - Don't save subquery results to a local file on the coordinator when the subquery is not in the having clause - Push the the HAVING with subquery to the workers if there's a group by on the distribution column - Don't push down the results to the workers when we don't push down the HAVING clause, only the coordinator needs it Fixes #520 Fixes #756 Closes #2047	2019-10-16 16:40:14 +02:00