mirror of https://github.com/citusdata/citus.git
83b25e1fb1
DESCRIPTION: Fixes a bug that causes an unexpected error when executing repartitioned merge. Fixes #8180. This was happening because of a bug in SourceResultPartitionColumnIndex(). And to fix it, this PR avoids using DistributionColumnIndex() in SourceResultPartitionColumnIndex(). Instead, invents FindTargetListEntryWithVarExprAttno(), which finds the index of the target entry in the source query's target list that can be used to repartition the source for a repartitioned merge. In short, to find the source target entry that refences the Var used in ON (..) clause and that references the source rte, we should check the varattno of the underlying expr, which presumably is always a Var for repartitioned merge as we always wrap the source rte with a subquery, where all target entries point to the columns of the original source relation. Using DistributionColumnIndex() prior to 13.0 wasn't causing such an issue because prior to 13.0, the varattno of the underlying expr of the source target entries was almost (*1) always equal to resno of the target entry as we were including all target entries of the source relation. However, starting with #7659, which is merged to main before 13.0, we started using CreateFilteredTargetListForRelation() instead of CreateAllTargetListForRelation() to compute the target entry list for the source rte to fix another bug. So we cannot revert to using CreateAllTargetListForRelation() because otherwise we would re-introduce bug that it helped fixing, so we instead had to find a way to properly deal with the "filtered target list"s, as in this commit. Plus (*1), even before #7659, probably we would still fail when the source relation has dropped attributes or such because that would probably also cause such a mismatch between the varattno of the underlying expr of the target entry and its resno. |
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