diff options
Diffstat (limited to 'src/backend/optimizer/README')
| -rw-r--r-- | src/backend/optimizer/README | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README index 2e736b6dbe2..bd302bc215c 100644 --- a/src/backend/optimizer/README +++ b/src/backend/optimizer/README @@ -223,8 +223,8 @@ rels to the OJ's syntactic rels may be legal. Per identities 1 and 2, non-FULL joins can be freely associated into the lefthand side of an OJ, but in general they can't be associated into the righthand side. So the restriction enforced by make_join_rel is that a proposed join -can't join across a RHS boundary (ie, join anything inside the RHS -to anything else) unless the join validly implements some outer join. +can't join a rel within or partly within an RHS boundary to one outside +the boundary, unless the join validly implements some outer join. (To support use of identity 3, we have to allow cases where an apparent violation of a lower OJ's RHS is committed while forming an upper OJ. If this wouldn't in fact be legal, the upper OJ's minimum LHS or RHS |