2f17b57017
The present implementations of adjust_appendrel_attrs_multilevel and its sibling adjust_child_relids_multilevel are very messy, because they work by reconstructing the relids of the child's immediate parent and then seeing if that's bms_equal to the relids of the target parent. Aside from being quite inefficient, this will not work with planned future changes to make joinrels' relid sets contain outer-join relids in addition to baserels. The whole thing can be solved at a stroke by adding explicit parent and top_parent links to child RelOptInfos, and making these functions work with RelOptInfo pointers instead of relids. Doing that is simpler for most callers, too. In my original version of this patch, I got rid of RelOptInfo.top_parent_relids on the grounds that it was now redundant. However, that adds a lot of code churn in places that otherwise would not need changing, and arguably the extra indirection needed to fetch top_parent->relids in those places costs something. So this version leaves that field in place. Discussion: https://postgr.es/m/553080.1657481916@sss.pgh.pa.us
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