Make auto_explain print the query identifier in verbose mode

When auto_explain.log_verbose is on, auto_explain should print in the
logs plans equivalent to the EXPLAIN (VERBOSE).  However, when
compute_query_id is on, query identifiers were not showing up, being
only handled by EXPLAIN (VERBOSE).  This brings auto_explain on par with
EXPLAIN regarding that.  Note that like EXPLAIN, auto_explain does not
show the query identifier when compute_query_id=regress.

The change is done so as the choice of printing the query identifier is
done in ExplainPrintPlan() rather than in ExplainOnePlan(), to avoid a
duplication of the logic dealing with the query ID.  auto_explain is the
only in-core caller of ExplainPrintPlan().

While looking at the area, I have noticed that more consolidation
between EXPLAIN and auto_explain would be in order for the logging of
the plan duration and the buffer usage.  This refactoring is left as a
future change.

Author: Atsushi Torikoshi
Reviewed-by: Justin Pryzby, Julien Rouhaud
Discussion: https://postgr.es/m/1ea21936981f161bccfce05765c03bee@oss.nttdata.com

Author: michaelpq

contrib/auto_explain/t/001_auto_explain.pl

@@ -106,6 +106,35 @@ sub query_log
 	qr/Query Parameters:/,
 	"query parameters not logged when disabled, text mode");
 
+# Query Identifier.
+# Logging enabled.
+$log_contents = query_log(
+	$node,
+	"SELECT * FROM pg_class;",
+	{
+		"auto_explain.log_verbose" => "on",
+		"compute_query_id"         => "on"
+	});
+
+like(
+	$log_contents,
+	qr/Query Identifier:/,
+	"query identifier logged with compute_query_id=on, text mode");
+
+# Logging disabled.
+$log_contents = query_log(
+	$node,
+	"SELECT * FROM pg_class;",
+	{
+		"auto_explain.log_verbose" => "on",
+		"compute_query_id"         => "regress"
+	});
+
+unlike(
+	$log_contents,
+	qr/Query Identifier:/,
+	"query identifier not logged with compute_query_id=regress, text mode");
+
 # JSON format.
 $log_contents = query_log(
 	$node,

src/backend/commands/explain.c

@@ -604,22 +604,6 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 	/* Create textual dump of plan tree */
 	ExplainPrintPlan(es, queryDesc);
 
-	/*
-	 * COMPUTE_QUERY_ID_REGRESS means COMPUTE_QUERY_ID_AUTO, but we don't show
-	 * the queryid in any of the EXPLAIN plans to keep stable the results
-	 * generated by regression test suites.
-	 */
-	if (es->verbose && plannedstmt->queryId != UINT64CONST(0) &&
-		compute_query_id != COMPUTE_QUERY_ID_REGRESS)
-	{
-		/*
-		 * Output the queryid as an int64 rather than a uint64 so we match
-		 * what would be seen in the BIGINT pg_stat_statements.queryid column.
-		 */
-		ExplainPropertyInteger("Query Identifier", NULL, (int64)
-							   plannedstmt->queryId, es);
-	}
-
 	/* Show buffer usage in planning */
 	if (bufusage)
 	{
@@ -791,6 +775,22 @@ ExplainPrintPlan(ExplainState *es, QueryDesc *queryDesc)
 	 * don't match the built-in defaults.
 	 */
 	ExplainPrintSettings(es);
+
+	/*
+	 * COMPUTE_QUERY_ID_REGRESS means COMPUTE_QUERY_ID_AUTO, but we don't show
+	 * the queryid in any of the EXPLAIN plans to keep stable the results
+	 * generated by regression test suites.
+	 */
+	if (es->verbose && queryDesc->plannedstmt->queryId != UINT64CONST(0) &&
+		compute_query_id != COMPUTE_QUERY_ID_REGRESS)
+	{
+		/*
+		 * Output the queryid as an int64 rather than a uint64 so we match
+		 * what would be seen in the BIGINT pg_stat_statements.queryid column.
+		 */
+		ExplainPropertyInteger("Query Identifier", NULL, (int64)
+							   queryDesc->plannedstmt->queryId, es);
+	}
 }
 
 /*