From 9ff79b9d4e71822a875c0f5e38f5ec86c7fb079f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 26 Aug 2012 22:48:55 -0400 Subject: Fix up planner infrastructure to support LATERAL properly. This patch takes care of a number of problems having to do with failure to choose valid join orders and incorrect handling of lateral references pulled up from subqueries. Notable changes: * Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to represent join ordering constraints created by lateral references. (I first considered extending the SpecialJoinInfo structure, but the semantics are different enough that a separate data structure seems better.) Extend join_is_legal() and related functions to prevent trying to form unworkable joins, and to ensure that we will consider joins that satisfy lateral references even if the joins would be clauseless. * Fill in the infrastructure needed for the last few types of relation scan paths to support parameterization. We'd have wanted this eventually anyway, but it is necessary now because a relation that gets pulled up out of a UNION ALL subquery may acquire a reltargetlist containing lateral references, meaning that its paths *have* to be parameterized whether or not we have any code that can push join quals down into the scan. * Compute data about lateral references early in query_planner(), and save in RelOptInfo nodes, to avoid repetitive calculations later. * Assorted corner-case bug fixes. There's probably still some bugs left, but this is a lot closer to being real than it was before. --- src/backend/nodes/copyfuncs.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'src/backend/nodes/copyfuncs.c') diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index 71d53234bc3..f34f7049e43 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -1906,6 +1906,20 @@ _copySpecialJoinInfo(const SpecialJoinInfo *from) return newnode; } +/* + * _copyLateralJoinInfo + */ +static LateralJoinInfo * +_copyLateralJoinInfo(const LateralJoinInfo *from) +{ + LateralJoinInfo *newnode = makeNode(LateralJoinInfo); + + COPY_SCALAR_FIELD(lateral_rhs); + COPY_BITMAPSET_FIELD(lateral_lhs); + + return newnode; +} + /* * _copyAppendRelInfo */ @@ -4082,6 +4096,9 @@ copyObject(const void *from) case T_SpecialJoinInfo: retval = _copySpecialJoinInfo(from); break; + case T_LateralJoinInfo: + retval = _copyLateralJoinInfo(from); + break; case T_AppendRelInfo: retval = _copyAppendRelInfo(from); break; -- cgit v1.2.3