diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index 48862d93aec..7b215f0075e 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -1537,7 +1537,8 @@ typedef struct LimitPath * if we decide that it can be pushed down into the nullable side of the join. * In that case it acts as a plain filter qual for wherever it gets evaluated. * (In short, is_pushed_down is only false for non-degenerate outer join - * conditions. Possibly we should rename it to reflect that meaning?) + * conditions. Possibly we should rename it to reflect that meaning? But + * see also the comments for RINFO_IS_PUSHED_DOWN, below.) * * RestrictInfo nodes also contain an outerjoin_delayed flag, which is true * if the clause's applicability must be delayed due to any outer joins @@ -1665,6 +1666,20 @@ typedef struct RestrictInfo } RestrictInfo; /* + * This macro embodies the correct way to test whether a RestrictInfo is + * "pushed down" to a given outer join, that is, should be treated as a filter + * clause rather than a join clause at that outer join. This is certainly so + * if is_pushed_down is true; but examining that is not sufficient anymore, + * because outer-join clauses will get pushed down to lower outer joins when + * we generate a path for the lower outer join that is parameterized by the + * LHS of the upper one. We can detect such a clause by noting that its + * required_relids exceed the scope of the join. + */ +#define RINFO_IS_PUSHED_DOWN(rinfo, joinrelids) \ + ((rinfo)->is_pushed_down || \ + !bms_is_subset((rinfo)->required_relids, joinrelids)) + +/* * Since mergejoinscansel() is a relatively expensive function, and would * otherwise be invoked many times while planning a large join tree, * we go out of our way to cache its results. Each mergejoinable |