Get latest tid on database with MAX(tid) instead of checking sequence

plone · May 12, 2017 · 0a7e276 · 0a7e276
1 parent d400912
commit 0a7e276
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Showing 2 changed files with 8 additions and 3 deletions.
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
@@ -1,7 +1,8 @@
 1.0.0a24 (unreleased)
 ---------------------
 
-- Nothing changed yet.
+- Get latest tid on database with MAX(tid) instead of checking sequence
+  [vangheem]
 
 
 1.0.0a23 (2017-05-11)

diff --git a/guillotina/db/storages/pg.py b/guillotina/db/storages/pg.py
@@ -100,7 +100,7 @@
 
 
 NEXT_TID = "SELECT nextval('tid_sequence');"
-MAX_TID = "SELECT last_value FROM tid_sequence;"
+MAX_TID = "SELECT MAX(tid) FROM objects;"
 
 
 NUM_CHILDREN = "SELECT count(*) FROM objects WHERE parent_id = $1::varchar(32)"
@@ -348,7 +348,11 @@ async def get_next_tid(self, txn):
     async def get_current_tid(self, txn):
         async with self._lock:
             # again, use storage lock here instead of trns lock
-            return await self._stmt_max_tid.fetchval()
+            result = await self._stmt_max_tid.fetchval()
+            if result is None:
+                # very first transaction won't have a value here...
+                return 0
+            return result
 
     async def start_transaction(self, txn):
         txn._db_txn = txn._db_conn.transaction(readonly=self._read_only)