Hi, On 12/17/2015 02:17 PM, David Rowley wrote:
On 17 December 2015 at 19:11, Simon Riggs <si...@2ndquadrant.com <mailto:si...@2ndquadrant.com>> wrote:On 17 December 2015 at 00:17, Tomas Vondra <tomas.von...@2ndquadrant.com <mailto:tomas.von...@2ndquadrant.com>> wrote: I'd go with match_first_tuple_only. +1 unique_inner is a state that has been detected, match_first_tuple_only is the action we take as a result. Ok great. I've made it so in the attached. This means the comment in the join code where we perform the skip can be a bit less verbose and all the details can go in where we're actually setting the match_first_tuple_only to true.
OK. I've looked at the patch again today, and it seems broken bv 45be99f8 as the partial paths were not passing the unique_inner to the create_*_path() functions. The attached patch should fix that.
Otherwise I think the patch is ready for committer - I think this is a valuable optimization and I see nothing wrong with the code.
Any objections to marking it accordingly? regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c index be410d2..1ec2ddc 100644 --- a/src/backend/optimizer/path/joinpath.c +++ b/src/backend/optimizer/path/joinpath.c @@ -411,7 +411,7 @@ try_partial_nestloop_path(PlannerInfo *root, * Before creating a path, get a quick lower bound on what it is likely * to cost. Bail out right away if it looks terrible. */ - initial_cost_nestloop(root, &workspace, jointype, + initial_cost_nestloop(root, &workspace, jointype, extra->unique_inner, outer_path, inner_path, extra->sjinfo, &extra->semifactors); if (!add_partial_path_precheck(joinrel, workspace.total_cost, pathkeys)) @@ -422,6 +422,7 @@ try_partial_nestloop_path(PlannerInfo *root, create_nestloop_path(root, joinrel, jointype, + extra->unique_inner, &workspace, extra->sjinfo, &extra->semifactors, @@ -622,6 +623,7 @@ try_partial_hashjoin_path(PlannerInfo *root, create_hashjoin_path(root, joinrel, jointype, + extra->unique_inner, &workspace, extra->sjinfo, &extra->semifactors,
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