perform ReScan in pickyappend_exec (required for IndexScans), restore previous EXPLAIN behavior

funbringer · funbringer · commit da48f475b2b3 · 2016-04-21T15:32:22.000+03:00
diff --git a/nodes_common.c b/nodes_common.c
@@ -13,6 +13,23 @@
 #include "pickyappend.h"
 
 
+
+/* Compare plans by 'original_order' */
+static int
+cmp_child_scan_common_by_orig_order(const void *ap,
+									const void *bp)
+{
+	ChildScanCommon a = *(ChildScanCommon *) ap;
+	ChildScanCommon b = *(ChildScanCommon *) bp;
+
+	if (a->original_order > b->original_order)
+		return 1;
+	else if (a->original_order < b->original_order)
+		return -1;
+	else
+		return 0;
+}
+
 static void
 free_child_scan_common_array(ChildScanCommon *cur_plans, int n)
 {
@@ -165,6 +182,7 @@ unpack_pickyappend_private(PickyAppendState *scan_state, CustomScan *cscan)
 	int			nchildren = list_length(custom_oids);
 	HTAB	   *children_table = scan_state->children_table;
 	HASHCTL	   *children_table_config = &scan_state->children_table_config;
+	int			i;
 
 	memset(children_table_config, 0, sizeof(HASHCTL));
 	children_table_config->keysize = sizeof(Oid);
@@ -174,6 +192,7 @@ unpack_pickyappend_private(PickyAppendState *scan_state, CustomScan *cscan)
 								 children_table_config,
 							     HASH_ELEM | HASH_BLOBS);
 
+	i = 0;
 	forboth (oid_cell, custom_oids, plan_cell, cscan->custom_plans)
 	{
 		bool				child_found;
@@ -186,6 +205,7 @@ unpack_pickyappend_private(PickyAppendState *scan_state, CustomScan *cscan)
 		Assert(!child_found); /* there should be no collisions */
 
 		child->content.plan = (Plan *) lfirst(plan_cell);
+		child->original_order = i++; /* will be used in EXPLAIN */
 	}
 
 	scan_state->children_table = children_table;
@@ -323,18 +343,6 @@ begin_append_common(CustomScanState *node, EState *estate, int eflags)
 	scan_state->plan_state_table = plan_state_table;
 	scan_state->custom_expr_states = (List *) ExecInitExpr((Expr *) scan_state->custom_exprs,
 														   (PlanState *) scan_state);
-
-	/*
-	 * ExecProcNode() won't ReScan plans without params, do this
-	 * provided that there are no external PARAM_EXEC params.
-	 *
-	 * rescan_append_common is required for prepared statements,
-	 * but at the same time we don't want it to be called several
-	 * times within a single run (for example, ExecNestLoop calls
-	 * ExecReScan itself)
-	 */
-	if (!node->ss.ps.chgParam && bms_is_empty(node->ss.ps.plan->extParam))
-		rescan_append_common(node);
 }
 
 void
@@ -393,5 +401,49 @@ rescan_append_common(CustomScanState *node)
 void
 explain_append_common(CustomScanState *node, HTAB* children_table, ExplainState *es)
 {
-	/* Nothing to do here */
+	PickyAppendState   *scan_state = (PickyAppendState *) node;
+
+	/* Construct excess PlanStates */
+	if (!es->analyze)
+	{
+		int					allocated = 10;
+		int					used = 0;
+		ChildScanCommon	   *custom_ps = palloc(allocated * sizeof(ChildScanCommon));
+		ChildScanCommon		child;
+		HASH_SEQ_STATUS		seqstat;
+		int					i;
+
+		/* There can't be any nodes since we're not scanning anything */
+		Assert(!node->custom_ps);
+
+		hash_seq_init(&seqstat, scan_state->children_table);
+
+		while ((child = (ChildScanCommon) hash_seq_search(&seqstat)))
+		{
+			if (allocated <= used)
+			{
+				allocated *= 2;
+				custom_ps = repalloc(custom_ps, allocated * sizeof(ChildScanCommon));
+			}
+
+			custom_ps[used++] = child;
+		}
+
+		/*
+		 * We have to restore the original plan order
+		 * which has been lost within the hash table
+		 */
+		qsort(custom_ps, used, sizeof(ChildScanCommon),
+			  cmp_child_scan_common_by_orig_order);
+
+		/*
+		 * These PlanStates will be used by EXPLAIN,
+		 * pickyappend_end will destroy them eventually
+		 */
+		for (i = 0; i < used; i++)
+			node->custom_ps = lappend(node->custom_ps,
+									  ExecInitNode(custom_ps[i]->content.plan,
+												   node->ss.ps.state,
+												   0));
+	}
 }
diff --git a/nodes_common.h b/nodes_common.h
@@ -33,6 +33,8 @@ typedef struct
 		Plan	   *plan;
 		PlanState  *plan_state;
 	}			content;
+
+	int		original_order;			/* for sorting in EXPLAIN */
 } ChildScanCommonData;
 
 typedef ChildScanCommonData *ChildScanCommon;
diff --git a/pickyappend.c b/pickyappend.c
@@ -60,6 +60,9 @@ pickyappend_exec(CustomScanState *node)
 {
 	PickyAppendState   *scan_state = (PickyAppendState *) node;
 
+	if (scan_state->ncur_plans == 0)
+		ExecReScan(&node->ss.ps);
+
 	while (scan_state->running_idx < scan_state->ncur_plans)
 	{
 		ChildScanCommon		child = scan_state->cur_plans[scan_state->running_idx];
@@ -85,6 +88,8 @@ pickyappend_exec(CustomScanState *node)
 		scan_state->running_idx++;
 	}
 
+	/* Force ReScan */
+	scan_state->ncur_plans = 0;
 	return NULL;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -60,6 +60,9 @@ pickyappend_exec(CustomScanState *node)`
`60`	`60`	`{`
`61`	`61`	`PickyAppendState scan_state = (PickyAppendState ) node;`
`62`	`62`
	`63`	`+ if (scan_state->ncur_plans == 0)`
	`64`	`+ ExecReScan(&node->ss.ps);`
	`65`	`+`
`63`	`66`	`while (scan_state->running_idx < scan_state->ncur_plans)`
`64`	`67`	`{`
`65`	`68`	`ChildScanCommon child = scan_state->cur_plans[scan_state->running_idx];`
`@@ -85,6 +88,8 @@ pickyappend_exec(CustomScanState *node)`
`85`	`88`	`scan_state->running_idx++;`
`86`	`89`	`}`
`87`	`90`
	`91`	`+ /* Force ReScan */`
	`92`	`+ scan_state->ncur_plans = 0;`
`88`	`93`	`return NULL;`
`89`	`94`	`}`
`90`	`95`