b7e2121ab7
When considering nestloop paths for individual partitions within a partitionwise join, if the inner path is parameterized, it is parameterized by the topmost parent of the outer rel, not the corresponding outer rel itself. Therefore, we need to translate the parameterization so that the inner path is parameterized by the corresponding outer rel. Up to now, we did this while generating join paths. However, that's problematic because we must also translate some expressions that are shared across all paths for a relation, such as restriction clauses (kept in the RelOptInfo and/or IndexOptInfo) and TableSampleClauses (kept in the RangeTblEntry). The existing code fails to translate these at all, leading to wrong answers, odd failures such as "variable not found in subplan target list", or executor crashes. But we can't modify them during path generation, because that would break things if we end up choosing some non-partitioned-join path. So this patch postpones reparameterization of the inner path until createplan.c, where it is safe to modify the referenced RangeTblEntry, RelOptInfo or IndexOptInfo, because we have made a final choice of which Path to use. We do still have to check during path generation that the reparameterization will be possible. So we introduce a new function path_is_reparameterizable_by_child() to detect that. The duplication between path_is_reparameterizable_by_child() and reparameterize_path_by_child() is a bit annoying, but there seems no other good answer. A small benefit is that we can avoid building useless reparameterized trees in cases where a non-partitioned join is ultimately chosen. Also, reparameterize_path_by_child() can now be allowed to scribble on the input paths, saving a few cycles. This fix repairs the same problems previously addressed in the back branches by commits 62f120203 et al. Richard Guo, reviewed at various times by Ashutosh Bapat, Andrei Lepikhov, Alena Rybakina, Robert Haas, and myself Discussion: https://postgr.es/m/CAMbWs496+N=UAjOc=rcD3P7B6oJe4rZw08e_TZRUsWbPxZW3Tw@mail.gmail.com
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
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