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, 2 insertions, 2 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index ee5c3a60ff3..28130fbc2b1 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -787,11 +787,11 @@ ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 		if (isTempNamespace(get_rel_namespace(rte->relid)))
 			continue;
 
-		PreventCommandIfReadOnly(CreateCommandTag((Node *) plannedstmt));
+		PreventCommandIfReadOnly(CreateCommandName((Node *) plannedstmt));
 	}
 
 	if (plannedstmt->commandType != CMD_SELECT || plannedstmt->hasModifyingCTE)
-		PreventCommandIfParallelMode(CreateCommandTag((Node *) plannedstmt));
+		PreventCommandIfParallelMode(CreateCommandName((Node *) plannedstmt));
 }