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Refactor pull_var_clause's API to make it less tedious to extend.

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In commit 1d97c19a0f and later c1d9579dd8, we extended
pull_var_clause's API by adding enum-type arguments.  That's sort of a pain
to maintain, though, because it means every time we add a new behavior we
must touch every last one of the call sites, even if there's a reasonable
default behavior that most of them could use.  Let's switch over to using a
bitmask of flags, instead; that seems more maintainable and might save a
nanosecond or two as well.  This commit changes no behavior in itself,
though I'm going to follow it up with one that does add a new behavior.

In passing, remove flatten_tlist(), which has not been used since 9.1
and would otherwise need the same API changes.

Removing these enums means that optimizer/tlist.h no longer needs to
depend on optimizer/var.h.  Changing that caused a number of C files to
need addition of #include "optimizer/var.h" (probably we can thank old
runs of pgrminclude for that); but on balance it seems like a good change
anyway.
This commit is contained in:
Tom Lane
2016-03-10 15:52:58 -05:00
parent 37c54863cf
commit 364a9f47ab
20 changed files with 94 additions and 128 deletions
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15
src/backend/optimizer/plan/setrefs.c
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@ -1641,12 +1641,12 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
*
* In most cases, we have to match up individual Vars in the tlist and
* qual expressions with elements of the subplan's tlist (which was
* generated by flatten_tlist() from these selfsame expressions, so it
* should have all the required variables). There is an important exception,
* however: GROUP BY and ORDER BY expressions will have been pushed into the
* subplan tlist unflattened. If these values are also needed in the output
* then we want to reference the subplan tlist element rather than recomputing
* the expression.
* generated by flattening these selfsame expressions, so it should have all
* the required variables). There is an important exception, however:
* depending on where we are in the plan tree, sort/group columns may have
* been pushed into the subplan tlist unflattened. If these values are also
* needed in the output then we want to reference the subplan tlist element
* rather than recomputing the expression.
*/
static void
set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
@ -2129,7 +2129,8 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
*
* An error is raised if no matching var can be found in the subplan tlist
* --- so this routine should only be applied to nodes whose subplans'
* targetlists were generated via flatten_tlist() or some such method.
* targetlists were generated by flattening the expressions used in the
* parent node.
*
* If itlist->has_non_vars is true, then we try to match whole subexpressions
* against elements of the subplan tlist, so that we can avoid recomputing