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Get rid of the planner's LateralJoinInfo data structure.

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I originally modeled this data structure on SpecialJoinInfo, but after
commit acfcd45cac that looks like a pretty poor decision.
All we really need is relid sets identifying laterally-referenced rels;
and most of the time, what we want to know about includes indirect lateral
references, a case the LateralJoinInfo data was unsuited to compute with
any efficiency.  The previous commit redefined RelOptInfo.lateral_relids
as the transitive closure of lateral references, so that it easily supports
checking indirect references.  For the places where we really do want just
direct references, add a new RelOptInfo field direct_lateral_relids, which
is easily set up as a copy of lateral_relids before we perform the
transitive closure calculation.  Then we can just drop lateral_info_list
and LateralJoinInfo and the supporting code.  This makes the planner's
handling of lateral references noticeably more efficient, and shorter too.

Such a change can't be back-patched into stable branches for fear of
breaking extensions that might be looking at the planner's data structures;
but it seems not too late to push it into 9.5, so I've done so.
This commit is contained in:
Tom Lane
2015-12-11 15:52:16 -05:00
parent ed8bec915e
commit 4fcf48450d
17 changed files with 100 additions and 289 deletions
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9
src/backend/optimizer/prep/prepjointree.c
View File

@@ -1150,14 +1150,11 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
subroot->append_rel_list);
/*
* We don't have to do the equivalent bookkeeping for outer-join or
* LATERAL info, because that hasn't been set up yet. placeholder_list
* likewise.
* We don't have to do the equivalent bookkeeping for outer-join info,
* because that hasn't been set up yet. placeholder_list likewise.
*/
Assert(root->join_info_list == NIL);
Assert(subroot->join_info_list == NIL);
Assert(root->lateral_info_list == NIL);
Assert(subroot->lateral_info_list == NIL);
Assert(root->placeholder_list == NIL);
Assert(subroot->placeholder_list == NIL);
@@ -1642,7 +1639,6 @@ pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
Assert(root->append_rel_list == NIL);
Assert(list_length(parse->rtable) == 1);
Assert(root->join_info_list == NIL);
Assert(root->lateral_info_list == NIL);
Assert(root->placeholder_list == NIL);
/*
@@ -2839,7 +2835,6 @@ substitute_multiple_relids_walker(Node *node,
}
/* Shouldn't need to handle planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, LateralJoinInfo));
Assert(!IsA(node, AppendRelInfo));
Assert(!IsA(node, PlaceHolderInfo));
Assert(!IsA(node, MinMaxAggInfo));

1
src/backend/optimizer/prep/prepunion.c
View File

@@ -1786,7 +1786,6 @@ adjust_appendrel_attrs_mutator(Node *node,
}
/* Shouldn't need to handle planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, LateralJoinInfo));
Assert(!IsA(node, AppendRelInfo));
Assert(!IsA(node, PlaceHolderInfo));
Assert(!IsA(node, MinMaxAggInfo));