Improve comments about RelOptInfo.reltargetlist.

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 9cb4370c8545cb778d23595a09f9c33fb32d912f..9934daa64a83f9875e3f60662b7d95516a3ed7eb 100644 (file)
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.160 2008/10/04 21:56:55 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.161 2008/10/17 20:23:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -244,8 +244,10 @@ typedef struct PlannerInfo
  *     width - avg. number of bytes per tuple in the relation after the
  *             appropriate projections have been done (ie, output width)
  *     reltargetlist - List of Var nodes for the attributes we need to
- *                     output from this relation (in no particular order)
- *                     NOTE: in a child relation, may contain RowExprs
+ *                     output from this relation (in no particular order,
+ *                     but all rels of an appendrel set must use same order)
+ *                     NOTE: in a child relation, may contain RowExpr or
+ *                     ConvertRowtypeExpr representing a whole-row Var
  *     pathlist - List of Path nodes, one for each potentially useful
  *                method of generating the relation
  *     cheapest_startup_path - the pathlist member with lowest startup cost
@@ -337,7 +339,7 @@ typedef struct RelOptInfo
    int         width;          /* estimated avg width of result tuples */
 
    /* materialization information */
-   List       *reltargetlist;  /* needed Vars */
+   List       *reltargetlist;  /* Vars to be output by scan of relation */
    List       *pathlist;       /* Path structures */
    struct Path *cheapest_startup_path;
    struct Path *cheapest_total_path;
@@ -350,7 +352,7 @@ typedef struct RelOptInfo
    AttrNumber  max_attr;       /* largest attrno of rel */
    Relids     *attr_needed;    /* array indexed [min_attr .. max_attr] */
    int32      *attr_widths;    /* array indexed [min_attr .. max_attr] */
-   List       *indexlist;
+   List       *indexlist;      /* list of IndexOptInfo */
    BlockNumber pages;
    double      tuples;
    struct Plan *subplan;       /* if subquery */