Enables use views within distributed queries.
User can create and use a view on distributed tables/queries
as he/she would use with regular queries.
After this change router queries will have full support for views,
insert into select queries will support reading from views, not
writing into. Outer joins would have a limited support, and would
error out at certain cases such as when a view is in the inner side
of the outer join.
Although PostgreSQL supports writing into views under certain circumstances.
We disallowed that for distributed views.
Adds support for PostgreSQL 9.6 by copying in the requisite ruleutils
file and refactoring the out/readfuncs code to flexibly support the
old-style copy/pasted out/readfuncs (prior to 9.6) or use extensible
node APIs (in 9.6 and higher).
Most version-specific code within this change is only needed to set new
fields in the AggRef nodes we build for aggregations. Version-specific
test output files were added in certain cases, though in most they were
not necessary. Each such file begins by e.g. printing the major version
in order to clarify its purpose.
The comment atop citus_nodes.h details how to add support for new nodes
for when that becomes necessary.
This commit completes having support in Citus by adding having support for
real-time and task-tracker executors. Multiple tests are added to regression
tests to cover new supported queries with having support.
In subquery pushdown, we allow outer joins if the join condition is on the
partition columns. WhereClauseList() used to return all join conditions including
outer joins. However, this has been changed with a commit related to outer join
support on regular queries. With this commit, we refactored ExtractFromExpressionWalker()
to return two lists of qualifiers. The first list is for inner join and filter
clauses and the second list is for outer join clauses. Therefore, we can also
use outer join clauses to check subquery pushdown prerequisites.
We can now support richer set of queries in router planner.
This allow us to support CTEs, joins, window function, subqueries
if they are known to be executed at a single worker with a single
task (all tables are filtered down to a single shard and a single
worker contains all table shards referenced in the query).
Fixes : #501
Murat Tuncer
Marco Slot
Andres Freund
Metin Doslu
Jason Petersen
Onder Kalaci