If an update query on a reference table has a returns clause with a
subquery that accesses some other local table, we end-up with an crash.
This commit prevents the crash, but does not prevent other error
messages from happening due to Citus not being able to pushdown the
results of that subquery in a valid SQL command.
Related: #6634
Before, this was the default mode for CustomScan providers.
Now, the default is to assume that they can't project.
This causes performance penalties due to adding unnecessary
Result nodes.
Hence we use the newly added flag, CUSTOMPATH_SUPPORT_PROJECTION
to get it back to how it was.
In PG15 support branch we created explain functions to ignore
the new Result nodes, so we undo that in this commit.
Relevant PG commit:
955b3e0f9269639fb916cee3dea37aee50b82df0
The codebase is updated to use varattnosync and varnosyn and we defined
the macros for older versions. This way we can just remove the macros
when we drop an older version.
The error message when index has opclassopts is improved and the commit
from postgres side is also included for future reference.
Also some minor style related changes are applied.
Hanefi Onaldi
aykut-bozkurt
Naisila Puka
Onder Kalaci
SaitTalhaNisanci
Marco Slot