[release/7.0] Fix to #29667 - Count after Take throws "No column name was specified for column 1 of 't'." #30144
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… for column 1 of 't'." Problem was that in some cases (e.g. count over keyless entity that has been pushed down) we now generate empty projection in the subquery, where before we were projecting some columns. SQL Server doesn't allow unaliased projection in the subquery, so the fix is to simply add an alias to the empty projection that we generate. Fixes #29667
roji
previously approved these changes
Jan 26, 2023
AndriySvyryd
approved these changes
Jan 26, 2023
|
@maumar Make sure to change the PR to target the release/7.0 branch. |
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Ported from #30134
Fixes #29667
Description
Query using keyless entities that also uses Take and Count throws SqlException.
Customer impact
Query using keyless entities that also uses Take and Count throws SqlException. Scenario is not common, but it is a regression and there is no good workaround for it. Only options are to not use keyless entities or perform Count on the client (which can be a significant perf hit)
How found
Customer report on 7.0.
Regression
Yes.
Testing
Added regression tests.
Risk
Low; Fix is very isolated, only affecting empty projection by adding an alias for it. Empty projection by definition can't be referenced in other parts of the query, so there is no risk of name clashes due to new alias. Also quirked.