1698: Stop temp schema purge from dropping the unlogged marker

api/src/org/labkey/api/data/MaterializedQueryHelper.java

@@ -1074,5 +1074,25 @@ public void testUnloggedReset()
                 assertEquals(Integer.valueOf(1), new SqlSelector(temp, new SQLFragment("SELECT COUNT(*) FROM ").append(after)).getObject(Integer.class));
             }
         }
+
+        @Test
+        public void testUnloggedMarkerDropped()
+        {
+            DbSchema temp = DbSchema.getTemp();
+            Assume.assumeTrue("UNLOGGED is only supported on PostgreSQL", temp.getSqlDialect().isPostgreSQL());
+
+            UnloggedTableGeneration.checkForTest();
+            String before = UnloggedTableGeneration.markerNameForTest();
+            assertNotNull("The initial check must create a marker", before);
+            long generation = Long.parseLong(UnloggedTableGeneration.current());
+
+            new SqlExecutor(temp).execute(new SQLFragment("DROP TABLE temp.").appendIdentifier(before));
+            UnloggedTableGeneration.checkForTest();
+
+            assertTrue("A dropped marker must bump the generation", Long.parseLong(UnloggedTableGeneration.current()) > generation);
+            String after = UnloggedTableGeneration.markerNameForTest();
+            assertNotEquals("A dropped marker must be replaced under a new name", before, after);
+            assertEquals(Integer.valueOf(1), new SqlSelector(temp, new SQLFragment("SELECT COUNT(*) FROM temp.").appendIdentifier(after)).getObject(Integer.class));
+        }
     }
 }

api/src/org/labkey/api/data/UnloggedTableGeneration.java

@@ -92,6 +92,11 @@ static void checkForTest()
         }
     }
 
+    static @Nullable String markerNameForTest()
+    {
+        return _markerName;
+    }
+
     /**
      * Empties the marker as a reset would and checks it immediately. Callers must empty their own UNLOGGED tables.
      * Invalidates every UNLOGGED materialized table on the server, not just the caller's.
@@ -146,6 +151,14 @@ private static String failureKind(Exception x)
 
     private static void verifyMarker(DbScope scope, Connection conn, String markerName)
     {
+        // A missing table fails the EXISTS query at parse time, and SqlSelector logs that failure at ERROR
+        SQLFragment found = new SQLFragment("SELECT to_regclass(?) IS NOT NULL", markerTable(markerName).getRawSQL());
+        if (!Boolean.TRUE.equals(new SqlSelector(scope, conn, found).getObject(Boolean.class)))
+        {
+            replaceMissingMarker(scope, conn, markerName);
+            return;
+        }
+
         try
         {
             SQLFragment exists = new SQLFragment("SELECT EXISTS (SELECT 1 FROM ").append(markerTable(markerName)).append(")");
@@ -161,15 +174,20 @@ private static void verifyMarker(DbScope scope, Connection conn, String markerNa
         {
             if (!SqlDialect.isObjectNotFoundException(x))
                 throw x;
-            createMarker(scope, conn);
-            _generation.incrementAndGet();
-            LOG.info("UNLOGGED table marker {} is missing. Materialized views will rebuild.", markerName);
+            replaceMissingMarker(scope, conn, markerName);
         }
     }
 
+    private static void replaceMissingMarker(DbScope scope, Connection conn, String markerName)
+    {
+        createMarker(scope, conn);
+        _generation.incrementAndGet();
+        LOG.info("UNLOGGED table marker {} is missing. Materialized views will rebuild.", markerName);
+    }
+
     private static void createMarker(DbScope scope, Connection conn)
     {
-        // A fresh name never collides with tables TempTableTracker purges asynchronously at startup
+        TempTableTracker.init();
         String name = "unlogged_marker_" + GUID.makeHash();
         new SqlExecutor(scope, conn).execute(new SQLFragment("CREATE UNLOGGED TABLE ").append(markerTable(name)).append(" AS SELECT 1 AS x"));
         TempTableTracker.track(name, MARKER_REF);