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, 4 insertions, 2 deletions

diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index b675575c315..7072ce48a3e 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -281,7 +281,7 @@ void
 PortalDefineQuery(Portal portal,
 				  const char *prepStmtName,
 				  const char *sourceText,
-				  const char *commandTag,
+				  CommandTag commandTag,
 				  List *stmts,
 				  CachedPlan *cplan)
 {
@@ -289,10 +289,12 @@ PortalDefineQuery(Portal portal,
 	AssertState(portal->status == PORTAL_NEW);
 
 	AssertArg(sourceText != NULL);
-	AssertArg(commandTag != NULL || stmts == NIL);
+	AssertArg(commandTag != CMDTAG_UNKNOWN || stmts == NIL);
 
 	portal->prepStmtName = prepStmtName;
 	portal->sourceText = sourceText;
+	portal->qc.commandTag = commandTag;
+	portal->qc.nprocessed = 0;
 	portal->commandTag = commandTag;
 	portal->stmts = stmts;
 	portal->cplan = cplan;