Rethink representation of index clauses' mapping to index columns.HEADmaster

In commit e2c2c2e8b1df7dfdb01e7e6f6191a569ce3c3195 I made use of nested
list structures to show which clauses went with which index columns, but
on reflection that's a data structure that only an old-line Lisp hacker
could love.  Worse, it adds unnecessary complication to the many places
that don't much care which clauses go with which index columns.  Revert
to the previous arrangement of flat lists of clauses, and instead add a
parallel integer list of column numbers.  The places that care about the
pairing can chase both lists with forboth(), while the places that don't
care just examine one list the same as before.

The only real downside to this is that there are now two more lists that
need to be passed to amcostestimate functions in case they care about
column matching (which btcostestimate does, so not passing the info is not
an option).  Rather than deal with 11-argument amcostestimate functions,
pass just the IndexPath and expect the functions to extract fields from it.
That gets us down to 7 arguments which is better than 11, and it seems
more future-proof against likely additions to the information we keep
about an index path.

7 files changed, 42 insertions, 34 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 94b7d89790..b2bf8f0d8c 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201112231
+#define CATALOG_VERSION_NO	201112241
 
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 32be6b1374..c893c3a170 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -548,7 +548,7 @@ DATA(insert OID = 972 (  btvacuumcleanup   PGNSP PGUID 12 1 0 0 0 f f f t f v 2
 DESCR("btree(internal)");
 DATA(insert OID = 276 (  btcanreturn	   PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 16 "2281" _null_ _null_ _null_ _null_ btcanreturn _null_ _null_ _null_ ));
 DESCR("btree(internal)");
-DATA(insert OID = 1268 (  btcostestimate   PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ btcostestimate _null_ _null_ _null_ ));
+DATA(insert OID = 1268 (  btcostestimate   PGNSP PGUID 12 1 0 0 0 f f f t f v 7 0 2278 "2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ btcostestimate _null_ _null_ _null_ ));
 DESCR("btree(internal)");
 DATA(insert OID = 2785 (  btoptions		   PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_  btoptions _null_ _null_ _null_ ));
 DESCR("btree(internal)");
@@ -662,7 +662,7 @@ DATA(insert OID = 442 (  hashbulkdelete    PGNSP PGUID 12 1 0 0 0 f f f t f v 4
 DESCR("hash(internal)");
 DATA(insert OID = 425 (  hashvacuumcleanup PGNSP PGUID 12 1 0 0 0 f f f t f v 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ hashvacuumcleanup _null_ _null_ _null_ ));
 DESCR("hash(internal)");
-DATA(insert OID = 438 (  hashcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ hashcostestimate _null_ _null_ _null_ ));
+DATA(insert OID = 438 (  hashcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 7 0 2278 "2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ hashcostestimate _null_ _null_ _null_ ));
 DESCR("hash(internal)");
 DATA(insert OID = 2786 (  hashoptions	   PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_  hashoptions _null_ _null_ _null_ ));
 DESCR("hash(internal)");
@@ -917,7 +917,7 @@ DATA(insert OID = 776 (  gistbulkdelete    PGNSP PGUID 12 1 0 0 0 f f f t f v 4
 DESCR("gist(internal)");
 DATA(insert OID = 2561 (  gistvacuumcleanup   PGNSP PGUID 12 1 0 0 0 f f f t f v 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ gistvacuumcleanup _null_ _null_ _null_ ));
 DESCR("gist(internal)");
-DATA(insert OID = 772 (  gistcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ gistcostestimate _null_ _null_ _null_ ));
+DATA(insert OID = 772 (  gistcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 7 0 2278 "2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ gistcostestimate _null_ _null_ _null_ ));
 DESCR("gist(internal)");
 DATA(insert OID = 2787 (  gistoptions	   PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_  gistoptions _null_ _null_ _null_ ));
 DESCR("gist(internal)");
@@ -3870,7 +3870,7 @@ DATA(insert OID = 2739 (  ginbulkdelete    PGNSP PGUID 12 1 0 0 0 f f f t f v 4
 DESCR("gin(internal)");
 DATA(insert OID = 2740 (  ginvacuumcleanup PGNSP PGUID 12 1 0 0 0 f f f t f v 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ ginvacuumcleanup _null_ _null_ _null_ ));
 DESCR("gin(internal)");
-DATA(insert OID = 2741 (  gincostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ gincostestimate _null_ _null_ _null_ ));
+DATA(insert OID = 2741 (  gincostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 7 0 2278 "2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ gincostestimate _null_ _null_ _null_ ));
 DESCR("gin(internal)");
 DATA(insert OID = 2788 (  ginoptions	   PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_  ginoptions _null_ _null_ _null_ ));
 DESCR("gin(internal)");
@@ -4530,7 +4530,7 @@ DATA(insert OID = 4012 (  spgvacuumcleanup   PGNSP PGUID 12 1 0 0 0 f f f t f v
 DESCR("spgist(internal)");
 DATA(insert OID = 4032 (  spgcanreturn	   PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 16 "2281" _null_ _null_ _null_ _null_ spgcanreturn _null_ _null_ _null_ ));
 DESCR("spgist(internal)");
-DATA(insert OID = 4013 (  spgcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ spgcostestimate _null_ _null_ _null_ ));
+DATA(insert OID = 4013 (  spgcostestimate  PGNSP PGUID 12 1 0 0 0 f f f t f v 7 0 2278 "2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ spgcostestimate _null_ _null_ _null_ ));
 DESCR("spgist(internal)");
 DATA(insert OID = 4014 (  spgoptions	   PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_  spgoptions _null_ _null_ _null_ ));
 DESCR("spgist(internal)");
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index b137142f3e..13018027b6 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -657,27 +657,33 @@ typedef struct Path
  *
  * 'indexclauses' is a list of index qualification clauses, with implicit
  * AND semantics across the list.  Each clause is a RestrictInfo node from
- * the query's WHERE or JOIN conditions.
- *
- * 'indexquals' is a list of sub-lists of the actual index qual conditions
- * that can be used with the index.  There is one possibly-empty sub-list
- * for each index column (but empty sub-lists for trailing columns can be
- * omitted).  The qual conditions are RestrictInfos, and in simple cases
- * are the same RestrictInfos that appear in the flat indexclauses list.
- * But when special indexable operators appear in 'indexclauses', they are
- * replaced by their derived indexscannable conditions in 'indexquals'.
- * Note that an entirely empty indexquals list denotes a full-index scan.
- *
- * 'indexorderbys', if not NIL, is a list of lists of lists of ORDER BY
- * expressions that have been found to be usable as ordering operators for an
- * amcanorderbyop index.  These are not RestrictInfos, just bare expressions,
+ * the query's WHERE or JOIN conditions.  An empty list implies a full
+ * index scan.
+ *
+ * 'indexquals' has the same structure as 'indexclauses', but it contains
+ * the actual index qual conditions that can be used with the index.
+ * In simple cases this is identical to 'indexclauses', but when special
+ * indexable operators appear in 'indexclauses', they are replaced by the
+ * derived indexscannable conditions in 'indexquals'.
+ *
+ * 'indexqualcols' is an integer list of index column numbers (zero-based)
+ * of the same length as 'indexquals', showing which index column each qual
+ * is meant to be used with.  'indexquals' is required to be ordered by
+ * index column, so 'indexqualcols' must form a nondecreasing sequence.
+ * (The order of multiple quals for the same index column is unspecified.)
+ *
+ * 'indexorderbys', if not NIL, is a list of ORDER BY expressions that have
+ * been found to be usable as ordering operators for an amcanorderbyop index.
+ * The list must match the path's pathkeys, ie, one expression per pathkey
+ * in the same order.  These are not RestrictInfos, just bare expressions,
  * since they generally won't yield booleans.  Also, unlike the case for
  * quals, it's guaranteed that each expression has the index key on the left
- * side of the operator.  The top list has one entry per pathkey in the
- * path's pathkeys, and the sub-lists have one sub-sublist per index column.
- * This representation is a bit of overkill, since there will be only one
- * actual expression per pathkey, but it's convenient because each sub-list
- * has the same structure as the indexquals list.
+ * side of the operator.
+ *
+ * 'indexorderbycols' is an integer list of index column numbers (zero-based)
+ * of the same length as 'indexorderbys', showing which index column each
+ * ORDER BY expression is meant to be used with.  (There is no restriction
+ * on which index column each ORDER BY can be used with.)
  *
  * 'isjoininner' is TRUE if the path is a nestloop inner scan (that is,
  * some of the index conditions are join rather than restriction clauses).
@@ -711,7 +717,9 @@ typedef struct IndexPath
 	IndexOptInfo *indexinfo;
 	List	   *indexclauses;
 	List	   *indexquals;
+	List	   *indexqualcols;
 	List	   *indexorderbys;
+	List	   *indexorderbycols;
 	bool		isjoininner;
 	ScanDirection indexscandir;
 	Cost		indextotalcost;
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 125808ae98..6c56439f10 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -67,9 +67,8 @@ extern double clamp_row_est(double nrows);
 extern double index_pages_fetched(double tuples_fetched, BlockNumber pages,
 					double index_pages, PlannerInfo *root);
 extern void cost_seqscan(Path *path, PlannerInfo *root, RelOptInfo *baserel);
-extern void cost_index(IndexPath *path, PlannerInfo *root, IndexOptInfo *index,
-		   List *indexQuals, List *indexOrderBys,
-		   bool indexonly, RelOptInfo *outer_rel);
+extern void cost_index(IndexPath *path, PlannerInfo *root,
+					   RelOptInfo *outer_rel);
 extern void cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
 					  Path *bitmapqual, RelOptInfo *outer_rel);
 extern void cost_bitmap_and_node(BitmapAndPath *path, PlannerInfo *root);
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 38c8c1c9a3..8eec2ac596 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -30,8 +30,10 @@ extern void add_path(RelOptInfo *parent_rel, Path *new_path);
 extern Path *create_seqscan_path(PlannerInfo *root, RelOptInfo *rel);
 extern IndexPath *create_index_path(PlannerInfo *root,
 				  IndexOptInfo *index,
-				  List *clause_groups,
+				  List *indexclauses,
+				  List *indexclausecols,
 				  List *indexorderbys,
+				  List *indexorderbycols,
 				  List *pathkeys,
 				  ScanDirection indexscandir,
 				  bool indexonly,
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index b0075d7865..2fa862fb6f 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -57,11 +57,10 @@ extern bool eclass_matches_any_index(EquivalenceClass *ec,
 						 RelOptInfo *rel);
 extern bool match_index_to_operand(Node *operand, int indexcol,
 					   IndexOptInfo *index);
-extern List *expand_indexqual_conditions(IndexOptInfo *index,
-							List *clausegroups);
+extern void expand_indexqual_conditions(IndexOptInfo *index,
+							List *indexclauses, List *indexclausecols,
+							List **indexquals_p, List **indexqualcols_p);
 extern void check_partial_indexes(PlannerInfo *root, RelOptInfo *rel);
-extern List *flatten_clausegroups_list(List *clausegroups);
-extern List *flatten_indexorderbys_list(List *indexorderbys);
 extern Expr *adjust_rowcompare_for_index(RowCompareExpr *clause,
 							IndexOptInfo *index,
 							int indexcol,
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index 6c8e31269c..ac434fabbc 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -22,7 +22,7 @@
 /*
  * Maximum number of arguments to a function.
  *
- * The minimum value is 9 (index cost estimation uses 9-argument functions).
+ * The minimum value is 8 (GIN indexes use 8-argument support functions).
  * The maximum possible value is around 600 (limited by index tuple size in
  * pg_proc's index; BLCKSZ larger than 8K would allow more).  Values larger
  * than needed will waste memory and processing time, but do not directly