New cost model for planning, incorporating a penalty for random page

accesses versus sequential accesses, a (very crude) estimate of the
effects of caching on random page accesses, and cost to evaluate WHERE-
clause expressions.  Export critical parameters for this model as SET
variables.  Also, create SET variables for the planner's enable flags
(enable_seqscan, enable_indexscan, etc) so that these can be controlled
more conveniently than via PGOPTIONS.

Planner now estimates both startup cost (cost before retrieving
first tuple) and total cost of each path, so it can optimize queries
with LIMIT on a reasonable basis by interpolating between these costs.
Same facility is a win for EXISTS(...) subqueries and some other cases.

Redesign pathkey representation to achieve a major speedup in planning
(I saw as much as 5X on a 10-way join); also minor changes in planner
to reduce memory consumption by recycling discarded Path nodes and
not constructing unnecessary lists.

Minor cleanups to display more-plausible costs in some cases in
EXPLAIN output.

Initdb forced by change in interface to index cost estimation
functions.

1 files changed, 16 insertions, 9 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index adf0c7f1987..5bf01e22722 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.105 2000/02/15 03:37:08 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.106 2000/02/15 20:49:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -75,7 +75,8 @@ listCopy(List *list)
 static void
 CopyPlanFields(Plan *from, Plan *newnode)
 {
-	newnode->cost = from->cost;
+	newnode->startup_cost = from->startup_cost;
+	newnode->total_cost = from->total_cost;
 	newnode->plan_rows = from->plan_rows;
 	newnode->plan_width = from->plan_width;
 	/* state is NOT copied */
@@ -981,8 +982,9 @@ _copyRelOptInfo(RelOptInfo *from)
 
 	Node_Copy(from, newnode, targetlist);
 	Node_Copy(from, newnode, pathlist);
-	/* XXX cheapestpath should point to a member of pathlist? */
-	Node_Copy(from, newnode, cheapestpath);
+	/* XXX cheapest-path fields should point to members of pathlist? */
+	Node_Copy(from, newnode, cheapest_startup_path);
+	Node_Copy(from, newnode, cheapest_total_path);
 	newnode->pruneable = from->pruneable;
 
 	newnode->indexed = from->indexed;
@@ -990,6 +992,7 @@ _copyRelOptInfo(RelOptInfo *from)
 	newnode->tuples = from->tuples;
 
 	Node_Copy(from, newnode, baserestrictinfo);
+	newnode->baserestrictcost = from->baserestrictcost;
 	Node_Copy(from, newnode, joininfo);
 	Node_Copy(from, newnode, innerjoin);
 
@@ -1045,6 +1048,7 @@ _copyIndexOptInfo(IndexOptInfo *from)
 	newnode->amcostestimate = from->amcostestimate;
 	newnode->indproc = from->indproc;
 	Node_Copy(from, newnode, indpred);
+	newnode->lossy = from->lossy;
 
 	return newnode;
 }
@@ -1066,7 +1070,8 @@ CopyPathFields(Path *from, Path *newnode)
 	 */
 	newnode->parent = from->parent;
 
-	newnode->path_cost = from->path_cost;
+	newnode->startup_cost = from->startup_cost;
+	newnode->total_cost = from->total_cost;
 
 	newnode->pathtype = from->pathtype;
 
@@ -1108,6 +1113,7 @@ _copyIndexPath(IndexPath *from)
 	 */
 	newnode->indexid = listCopy(from->indexid);
 	Node_Copy(from, newnode, indexqual);
+	newnode->indexscandir = from->indexscandir;
 	newnode->joinrelids = listCopy(from->joinrelids);
 
 	return newnode;
@@ -1339,8 +1345,7 @@ _copyRangeTblEntry(RangeTblEntry *from)
 
 	if (from->relname)
 		newnode->relname = pstrdup(from->relname);
-	if (from->ref)
-		Node_Copy(from, newnode, ref);
+	Node_Copy(from, newnode, ref);
 	newnode->relid = from->relid;
 	newnode->inh = from->inh;
 	newnode->inFromCl = from->inFromCl;
@@ -1449,8 +1454,10 @@ _copyQuery(Query *from)
 	Node_Copy(from, newnode, limitOffset);
 	Node_Copy(from, newnode, limitCount);
 
-	/* we do not copy the planner internal fields: base_rel_list,
-	 * join_rel_list, query_pathkeys.  Not entirely clear if this is right?
+	/*
+	 * We do not copy the planner internal fields: base_rel_list,
+	 * join_rel_list, equi_key_list, query_pathkeys.
+	 * Not entirely clear if this is right?
 	 */
 
 	return newnode;