Change EXPLAIN output so that subplans and initplans (particularly CTEs)

are individually labeled, rather than just grouped under an "InitPlan"
or "SubPlan" heading.  This in turn makes it possible for decompilation of
a subplan reference to usefully identify which subplan it's referencing.
I also made InitPlans identify which parameter symbol(s) they compute,
so that references to those parameters elsewhere in the plan tree can
be connected to the initplan that will be executed.  Per a gripe from
Robert Haas about EXPLAIN output of a WITH query being inadequate,
plus some longstanding pet peeves of my own.

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 8ad877e..d8f27a1 100644 (file)
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.184 2009/01/02 20:42:00 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.185 2009/04/05 19:59:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -951,9 +951,6 @@ explain_outNode(StringInfo str,
        {
                ListCell   *lst;
 
-               for (i = 0; i < indent; i++)
-                       appendStringInfo(str, "  ");
-               appendStringInfo(str, "  InitPlan\n");
                foreach(lst, planstate->initPlan)
                {
                        SubPlanState *sps = (SubPlanState *) lfirst(lst);
@@ -961,6 +958,9 @@ explain_outNode(StringInfo str,
 
                        for (i = 0; i < indent; i++)
                                appendStringInfo(str, "  ");
+                       appendStringInfo(str, "  %s\n", sp->plan_name);
+                       for (i = 0; i < indent; i++)
+                               appendStringInfo(str, "  ");
                        appendStringInfo(str, "    ->  ");
                        explain_outNode(str,
                                                        exec_subplan_get_plan(es->pstmt, sp),
@@ -1099,9 +1099,6 @@ explain_outNode(StringInfo str,
        {
                ListCell   *lst;
 
-               for (i = 0; i < indent; i++)
-                       appendStringInfo(str, "  ");
-               appendStringInfo(str, "  SubPlan\n");
                foreach(lst, planstate->subPlan)
                {
                        SubPlanState *sps = (SubPlanState *) lfirst(lst);
@@ -1109,6 +1106,9 @@ explain_outNode(StringInfo str,
 
                        for (i = 0; i < indent; i++)
                                appendStringInfo(str, "  ");
+                       appendStringInfo(str, "  %s\n", sp->plan_name);
+                       for (i = 0; i < indent; i++)
+                               appendStringInfo(str, "  ");
                        appendStringInfo(str, "    ->  ");
                        explain_outNode(str,
                                                        exec_subplan_get_plan(es->pstmt, sp),

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index bbeac65..5fac94f 100644 (file)
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.428 2009/04/04 21:12:31 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.429 2009/04/05 19:59:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1116,6 +1116,7 @@ _copySubPlan(SubPlan *from)
        COPY_NODE_FIELD(testexpr);
        COPY_NODE_FIELD(paramIds);
        COPY_SCALAR_FIELD(plan_id);
+       COPY_STRING_FIELD(plan_name);
        COPY_SCALAR_FIELD(firstColType);
        COPY_SCALAR_FIELD(firstColTypmod);
        COPY_SCALAR_FIELD(useHashTable);

diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index c5f09ca..36f2bcc 100644 (file)
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -22,7 +22,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.351 2009/04/04 21:12:31 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.352 2009/04/05 19:59:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -341,6 +341,7 @@ _equalSubPlan(SubPlan *a, SubPlan *b)
        COMPARE_NODE_FIELD(testexpr);
        COMPARE_NODE_FIELD(paramIds);
        COMPARE_SCALAR_FIELD(plan_id);
+       COMPARE_STRING_FIELD(plan_name);
        COMPARE_SCALAR_FIELD(firstColType);
        COMPARE_SCALAR_FIELD(firstColTypmod);
        COMPARE_SCALAR_FIELD(useHashTable);

diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index f3ca8d3..67f0513 100644 (file)
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.357 2009/04/04 21:12:31 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.358 2009/04/05 19:59:40 tgl Exp $
  *
  * NOTES
  *       Every node type that can appear in stored rules' parsetrees *must*
@@ -961,6 +961,7 @@ _outSubPlan(StringInfo str, SubPlan *node)
        WRITE_NODE_FIELD(testexpr);
        WRITE_NODE_FIELD(paramIds);
        WRITE_INT_FIELD(plan_id);
+       WRITE_STRING_FIELD(plan_name);
        WRITE_OID_FIELD(firstColType);
        WRITE_INT_FIELD(firstColTypmod);
        WRITE_BOOL_FIELD(useHashTable);

diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 2cf177a..595ff1d 100644 (file)
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.147 2009/03/10 22:09:26 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.148 2009/04/05 19:59:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -412,8 +412,8 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable,
        int                     paramid;
 
        /*
-        * Initialize the SubPlan node.  Note plan_id isn't set till further down,
-        * likewise the cost fields.
+        * Initialize the SubPlan node.  Note plan_id, plan_name, and cost fields
+        * are set further down.
         */
        splan = makeNode(SubPlan);
        splan->subLinkType = subLinkType;
@@ -606,6 +606,30 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable,
                root->glob->rewindPlanIDs = bms_add_member(root->glob->rewindPlanIDs,
                                                                                                   splan->plan_id);
 
+       /* Label the subplan for EXPLAIN purposes */
+       if (isInitPlan)
+       {
+               ListCell   *lc;
+               int                     offset;
+
+               splan->plan_name = palloc(32 + 12 * list_length(splan->setParam));
+               sprintf(splan->plan_name, "InitPlan %d (returns ", splan->plan_id);
+               offset = strlen(splan->plan_name);
+               foreach(lc, splan->setParam)
+               {
+                       sprintf(splan->plan_name + offset, "$%d%s",
+                                       lfirst_int(lc),
+                                       lnext(lc) ? "," : "");
+                       offset += strlen(splan->plan_name + offset);
+               }
+               sprintf(splan->plan_name + offset, ")");
+       }
+       else
+       {
+               splan->plan_name = palloc(32);
+               sprintf(splan->plan_name, "SubPlan %d", splan->plan_id);
+       }
+
        /* Lastly, fill in the cost estimates for use later */
        cost_subplan(root, splan, plan);
 
@@ -875,7 +899,7 @@ SS_process_ctes(PlannerInfo *root)
                 * Make a SubPlan node for it.  This is just enough unlike
                 * build_subplan that we can't share code.
                 *
-                * Note plan_id isn't set till further down, likewise the cost fields.
+                * Note plan_id, plan_name, and cost fields are set further down.
                 */
                splan = makeNode(SubPlan);
                splan->subLinkType = CTE_SUBLINK;
@@ -931,6 +955,10 @@ SS_process_ctes(PlannerInfo *root)
 
                root->cte_plan_ids = lappend_int(root->cte_plan_ids, splan->plan_id);
 
+               /* Label the subplan for EXPLAIN purposes */
+               splan->plan_name = palloc(4 + strlen(cte->ctename) + 1);
+               sprintf(splan->plan_name, "CTE %s", cte->ctename);
+
                /* Lastly, fill in the cost estimates for use later */
                cost_subplan(root, splan, plan);
        }
@@ -2134,5 +2162,10 @@ SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
        prm = generate_new_param(root, resulttype, resulttypmod);
        node->setParam = list_make1_int(prm->paramid);
 
+       /* Label the subplan for EXPLAIN purposes */
+       node->plan_name = palloc(64);
+       sprintf(node->plan_name, "InitPlan %d (returns $%d)",
+                       node->plan_id, prm->paramid);
+
        return prm;
 }

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index f05e6a2..8d06f54 100644 (file)
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.296 2009/02/25 18:00:01 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.297 2009/04/05 19:59:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -4404,20 +4404,42 @@ get_rule_expr(Node *node, deparse_context *context,
 
                case T_SubPlan:
                        {
+                               SubPlan *subplan = (SubPlan *) node;
+
                                /*
                                 * We cannot see an already-planned subplan in rule deparsing,
-                                * only while EXPLAINing a query plan. For now, just punt.
+                                * only while EXPLAINing a query plan.  We don't try to
+                                * reconstruct the original SQL, just reference the subplan
+                                * that appears elsewhere in EXPLAIN's result.
                                 */
-                               if (((SubPlan *) node)->useHashTable)
-                                       appendStringInfo(buf, "(hashed subplan)");
+                               if (subplan->useHashTable)
+                                       appendStringInfo(buf, "(hashed %s)", subplan->plan_name);
                                else
-                                       appendStringInfo(buf, "(subplan)");
+                                       appendStringInfo(buf, "(%s)", subplan->plan_name);
                        }
                        break;
 
                case T_AlternativeSubPlan:
-                       /* As above, just punt */
-                       appendStringInfo(buf, "(alternative subplans)");
+                       {
+                               AlternativeSubPlan *asplan = (AlternativeSubPlan *) node;
+                               ListCell   *lc;
+
+                               /* As above, this can only happen during EXPLAIN */
+                               appendStringInfo(buf, "(alternatives: ");
+                               foreach(lc, asplan->subplans)
+                               {
+                                       SubPlan    *splan = (SubPlan *) lfirst(lc);
+
+                                       Assert(IsA(splan, SubPlan));
+                                       if (splan->useHashTable)
+                                               appendStringInfo(buf, "hashed %s", splan->plan_name);
+                                       else
+                                               appendStringInfo(buf, "%s", splan->plan_name);
+                                       if (lnext(lc))
+                                               appendStringInfo(buf, " or ");
+                               }
+                               appendStringInfo(buf, ")");
+                       }
                        break;
 
                case T_FieldSelect:

diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 9cb4e8e..7fc7c00 100644 (file)
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.147 2009/03/10 22:09:26 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.148 2009/04/05 19:59:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -502,6 +502,8 @@ typedef struct SubPlan
        List       *paramIds;           /* IDs of Params embedded in the above */
        /* Identification of the Plan tree to use: */
        int                     plan_id;                /* Index (from 1) in PlannedStmt.subplans */
+       /* Identification of the SubPlan for EXPLAIN and debugging purposes: */
+       char       *plan_name;          /* A name assigned during planning */
        /* Extra data useful for determining subplan's output type: */
        Oid                     firstColType;   /* Type of first column of subplan result */
        int32           firstColTypmod; /* Typmod of first column of subplan result */