Represent command completion tags as structs

The backend was using strings to represent command tags and doing string
comparisons in multiple places, but that's slow and unhelpful.  Create a
new command list with a supporting structure to use instead; this is
stored in a tag-list-file that can be tailored to specific purposes with
a caller-definable C macro, similar to what we do for WAL resource
managers.  The first first such uses are a new CommandTag enum and a
CommandTagBehavior struct.

Replace numerous occurrences of char *completionTag with a
QueryCompletion struct so that the code no longer stores information
about completed queries in a cstring.  Only at the last moment, in
EndCommand(), does this get converted to a string.

EventTriggerCacheItem no longer holds an array of palloc’d tag strings
in sorted order, but rather just a Bitmapset over the CommandTags.

Author: Mark Dilger, with unsolicited help from Álvaro Herrera
Reviewed-by: John Naylor, Tom Lane
Discussion: https://postgr.es/m/981A9DB4-3F0C-4DA5-88AD-CB9CFF4D6CAD@enterprisedb.com

1 files changed, 14 insertions, 19 deletions

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 23661ae15f5..9dba3b0566a 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1064,8 +1064,8 @@ exec_simple_query(const char *query_string)
 	{
 		RawStmt    *parsetree = lfirst_node(RawStmt, parsetree_item);
 		bool		snapshot_set = false;
-		const char *commandTag;
-		char		completionTag[COMPLETION_TAG_BUFSIZE];
+		CommandTag	commandTag;
+		QueryCompletion qc;
 		MemoryContext per_parsetree_context = NULL;
 		List	   *querytree_list,
 				   *plantree_list;
@@ -1081,7 +1081,7 @@ exec_simple_query(const char *query_string)
 		 */
 		commandTag = CreateCommandTag(parsetree->stmt);
 
-		set_ps_display(commandTag, false);
+		set_ps_display(GetCommandTagName(commandTag), false);
 
 		BeginCommand(commandTag, dest);
 
@@ -1239,7 +1239,7 @@ exec_simple_query(const char *query_string)
 						 true,
 						 receiver,
 						 receiver,
-						 completionTag);
+						 &qc);
 
 		receiver->rDestroy(receiver);
 
@@ -1290,7 +1290,7 @@ exec_simple_query(const char *query_string)
 		 * command the client sent, regardless of rewriting. (But a command
 		 * aborted by error will not send an EndCommand report at all.)
 		 */
-		EndCommand(completionTag, dest);
+		EndCommand(&qc, dest, false);
 
 		/* Now we may drop the per-parsetree context, if one was created. */
 		if (per_parsetree_context)
@@ -1352,7 +1352,6 @@ exec_parse_message(const char *query_string,	/* string to execute */
 	MemoryContext oldcontext;
 	List	   *parsetree_list;
 	RawStmt    *raw_parse_tree;
-	const char *commandTag;
 	List	   *querytree_list;
 	CachedPlanSource *psrc;
 	bool		is_named;
@@ -1439,11 +1438,6 @@ exec_parse_message(const char *query_string,	/* string to execute */
 		raw_parse_tree = linitial_node(RawStmt, parsetree_list);
 
 		/*
-		 * Get the command name for possible use in status display.
-		 */
-		commandTag = CreateCommandTag(raw_parse_tree->stmt);
-
-		/*
 		 * If we are in an aborted transaction, reject all commands except
 		 * COMMIT/ROLLBACK.  It is important that this test occur before we
 		 * try to do parse analysis, rewrite, or planning, since all those
@@ -1463,7 +1457,8 @@ exec_parse_message(const char *query_string,	/* string to execute */
 		 * Create the CachedPlanSource before we do parse analysis, since it
 		 * needs to see the unmodified raw parse tree.
 		 */
-		psrc = CreateCachedPlan(raw_parse_tree, query_string, commandTag);
+		psrc = CreateCachedPlan(raw_parse_tree, query_string,
+								CreateCommandTag(raw_parse_tree->stmt));
 
 		/*
 		 * Set up a snapshot if parse analysis will need one.
@@ -1514,8 +1509,8 @@ exec_parse_message(const char *query_string,	/* string to execute */
 	{
 		/* Empty input string.  This is legal. */
 		raw_parse_tree = NULL;
-		commandTag = NULL;
-		psrc = CreateCachedPlan(raw_parse_tree, query_string, commandTag);
+		psrc = CreateCachedPlan(raw_parse_tree, query_string,
+								CMDTAG_UNKNOWN);
 		querytree_list = NIL;
 	}
 
@@ -2031,7 +2026,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 	DestReceiver *receiver;
 	Portal		portal;
 	bool		completed;
-	char		completionTag[COMPLETION_TAG_BUFSIZE];
+	QueryCompletion qc;
 	const char *sourceText;
 	const char *prepStmtName;
 	ParamListInfo portalParams;
@@ -2058,7 +2053,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 	 * If the original query was a null string, just return
 	 * EmptyQueryResponse.
 	 */
-	if (portal->commandTag == NULL)
+	if (portal->commandTag == CMDTAG_UNKNOWN)
 	{
 		Assert(portal->stmts == NIL);
 		NullCommand(dest);
@@ -2104,7 +2099,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 
 	pgstat_report_activity(STATE_RUNNING, sourceText);
 
-	set_ps_display(portal->commandTag, false);
+	set_ps_display(GetCommandTagName(portal->commandTag), false);
 
 	if (save_log_statement_stats)
 		ResetUsage();
@@ -2185,7 +2180,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 						  !execute_is_fetch && max_rows == FETCH_ALL,
 						  receiver,
 						  receiver,
-						  completionTag);
+						  &qc);
 
 	receiver->rDestroy(receiver);
 
@@ -2218,7 +2213,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 		}
 
 		/* Send appropriate CommandComplete to client */
-		EndCommand(completionTag, dest);
+		EndCommand(&qc, dest, false);
 	}
 	else
 	{