diff options
Diffstat (limited to 'src/backend/optimizer/util/pathnode.c')
| -rw-r--r-- | src/backend/optimizer/util/pathnode.c | 44 |
1 files changed, 43 insertions, 1 deletions
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 98227355605..84896b939fd 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.81 2002/11/30 00:08:20 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.82 2002/11/30 05:21:03 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -16,6 +16,7 @@ #include <math.h> +#include "executor/executor.h" #include "nodes/plannodes.h" #include "optimizer/cost.h" #include "optimizer/pathnode.h" @@ -450,6 +451,7 @@ create_result_path(RelOptInfo *rel, Path *subpath, List *constantqual) pathnode->subpath = subpath; pathnode->constantqual = constantqual; + /* Ideally should define cost_result(), but I'm too lazy */ if (subpath) { pathnode->path.startup_cost = subpath->startup_cost; @@ -465,6 +467,31 @@ create_result_path(RelOptInfo *rel, Path *subpath, List *constantqual) } /* + * create_material_path + * Creates a path corresponding to a Material plan, returning the + * pathnode. + */ +MaterialPath * +create_material_path(RelOptInfo *rel, Path *subpath) +{ + MaterialPath *pathnode = makeNode(MaterialPath); + + pathnode->path.pathtype = T_Material; + pathnode->path.parent = rel; + + pathnode->path.pathkeys = subpath->pathkeys; + + pathnode->subpath = subpath; + + cost_material(&pathnode->path, + subpath->total_cost, + rel->rows, + rel->width); + + return pathnode; +} + +/* * create_subqueryscan_path * Creates a path corresponding to a sequential scan of a subquery, * returning the pathnode. @@ -583,6 +610,21 @@ create_mergejoin_path(Query *root, if (innersortkeys && pathkeys_contained_in(innersortkeys, inner_path->pathkeys)) innersortkeys = NIL; + /* + * If we are not sorting the inner path, we may need a materialize + * node to ensure it can be marked/restored. (Sort does support + * mark/restore, so no materialize is needed in that case.) + * + * Since the inner side must be ordered, and only Sorts and IndexScans + * can create order to begin with, you might think there's no problem + * --- but you'd be wrong. Nestloop and merge joins can *preserve* + * the order of their inputs, so they can be selected as the input of + * a mergejoin, and they don't support mark/restore at present. + */ + if (innersortkeys == NIL && + !ExecSupportsMarkRestore(inner_path->pathtype)) + inner_path = (Path *) + create_material_path(inner_path->parent, inner_path); pathnode->jpath.path.pathtype = T_MergeJoin; pathnode->jpath.path.parent = joinrel; |