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/[email protected]

1 files changed, 1 insertions, 2 deletions

diff --git a/src/include/utils/evtcache.h b/src/include/utils/evtcache.h
index 6c3ff81ba37..bc8ce480615 100644
--- a/src/include/utils/evtcache.h
+++ b/src/include/utils/evtcache.h
@@ -28,8 +28,7 @@ typedef struct
 {
 	Oid			fnoid;			/* function to be called */
 	char		enabled;		/* as SESSION_REPLICATION_ROLE_* */
-	int			ntags;			/* number of command tags */
-	char	  **tag;			/* command tags in SORTED order */
+	Bitmapset  *tagset;			/* command tags, or NULL if empty */
 } EventTriggerCacheItem;
 
 extern List *EventCacheLookup(EventTriggerEvent event);