diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index c67c067a5f2..dac7d959bbd 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.134 2007/01/22 20:00:40 tgl Exp $ + * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.135 2007/02/16 20:57:19 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -797,14 +797,14 @@ typedef struct HashPath * join, we prevent it from being evaluated below the outer join's joinrel. * When we do form the outer join's joinrel, we still need to distinguish * those quals that are actually in that join's JOIN/ON condition from those - * that appeared higher in the tree and were pushed down to the join rel + * that appeared elsewhere in the tree and were pushed down to the join rel * because they used no other rels. That's what the is_pushed_down flag is - * for; it tells us that a qual came from a point above the join of the - * set of base rels listed in required_relids. A clause that originally came - * from WHERE will *always* have its is_pushed_down flag set; a clause that - * came from an INNER JOIN condition, but doesn't use all the rels being - * joined, will also have is_pushed_down set because it will get attached to - * some lower joinrel. + * for; it tells us that a qual is not an OUTER JOIN qual for the set of base + * rels listed in required_relids. A clause that originally came from WHERE + * or an INNER JOIN condition will *always* have its is_pushed_down flag set. + * It's possible for an OUTER JOIN clause to be marked is_pushed_down too, + * 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. * * When application of a qual must be delayed by outer join, we also mark it * with outerjoin_delayed = true. This isn't redundant with required_relids |