diff options
Diffstat (limited to 'src/backend/optimizer/util/clauses.c')
| -rw-r--r-- | src/backend/optimizer/util/clauses.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index 3427302c8de..ad320dcd047 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.36 1999/06/19 03:41:45 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.37 1999/06/21 01:18:02 tgl Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -810,7 +810,8 @@ CommuteClause(Node *clause) * The walker routine should return "false" to continue the tree walk, or * "true" to abort the walk and immediately return "true" to the top-level * caller. This can be used to short-circuit the traversal if the walker - * has found what it came for. + * has found what it came for. "false" is returned to the top-level caller + * iff no invocation of the walker returned "true". * * The node types handled by expression_tree_walker include all those * normally found in target lists and qualifier clauses during the planning @@ -827,10 +828,11 @@ CommuteClause(Node *clause) * appropriate behavior by recognizing subplan nodes and doing the right * thing. * - * Bare SubLink nodes (without a SUBPLAN_EXPR) will trigger an error unless - * detected and processed by the walker. We expect that walkers used before - * sublink processing is done will handle them properly. (XXX Maybe ignoring - * them would be better default behavior?) + * Bare SubLink nodes (without a SUBPLAN_EXPR) are handled by recursing into + * the "lefthand" argument list only. (A bare SubLink should be seen only if + * the tree has not yet been processed by subselect.c.) Again, this can be + * overridden by the walker, but it seems to be the most useful default + * behavior. *-------------------- */ @@ -923,6 +925,12 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context) return true; } break; + case T_SubLink: + /* A "bare" SubLink (note we will not come here if we found + * a SUBPLAN_EXPR node above). Examine the lefthand side, + * but not the oper list nor the subquery. + */ + return walker(((SubLink *) node)->lefthand, context); case T_List: foreach(temp, (List *) node) { |