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Fix comments for ChangeVarNodes() and related functions

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The comment for ChangeVarNodes() refers to a parameter named
change_RangeTblRef, which does not exist in the code.

The comment for ChangeVarNodesExtended() contains an extra space,
while the comment for replace_relid_callback() has an awkward line
break and a typo.

This patch fixes these issues and revises some sentences for smoother
wording.

Oversights in commits ab42d643c and fc069a3a6.

Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs480j16HC1JtjKCgj5WshivT8ZJYkOfTyZAM0POjFomJkg@mail.gmail.com
Backpatch-through: 18
This commit is contained in:
Richard Guo
2025-11-05 12:29:31 +09:00
parent 2fc3107962
commit 59dec6c0b0
2 changed files with 17 additions and 20 deletions
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18
src/backend/optimizer/plan/analyzejoins.c
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@@ -1683,14 +1683,14 @@ add_non_redundant_clauses(PlannerInfo *root,
}
/*
* A custom callback for ChangeVarNodesExtended() providing
* Self-join elimination (SJE) related functionality
* A custom callback for ChangeVarNodesExtended() providing Self-join
* elimination (SJE) related functionality
*
* SJE needs to skip the RangeTblRef node
* type. During SJE's last step, remove_rel_from_joinlist() removes
* remaining RangeTblRefs with target relid. If ChangeVarNodes() replaces
* the target relid before, remove_rel_from_joinlist() fails to identify
* the nodes to delete.
* SJE needs to skip the RangeTblRef node type. During SJE's last
* step, remove_rel_from_joinlist() removes remaining RangeTblRefs
* with target relid. If ChangeVarNodes() replaces the target relid
* before, remove_rel_from_joinlist() would fail to identify the nodes
* to delete.
*
* SJE also needs to change the relids within RestrictInfo's.
*/
@@ -1769,8 +1769,8 @@ replace_relid_callback(Node *node, ChangeVarNodes_context *context)
/*
* For self-join elimination, changing varnos could transform
* "t1.a = t2.a" into "t1.a = t1.a". That is always true as long
* as "t1.a" is not null. We use qual() to check for such a case,
* and then we replace the qual for a check for not null
* as "t1.a" is not null. We use equal() to check for such a
* case, and then we replace the qual with a check for not null
* (NullTest).
*/
if (leftOp != NULL && equal(leftOp, rightOp))