Merge pull request #202 from yesodweb/warnAboutTruncate

Warn that TRUNCATEing many tables with Postgres can become slow
yesodweb · Jun 28, 2020 · 55c7460 · 55c7460
2 parents a9e866c + 77cda01
commit 55c7460
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/test/TestImport.hs b/test/TestImport.hs
@@ -52,6 +52,10 @@ wipeDB app = runDBWithApp app $ do
     tables <- getTables
     sqlBackend <- ask
 
+    -- TRUNCATEing all tables is the simplest approach to wiping the database.
+    -- Should your application grow to hundreds of tables and tests,
+    -- switching to DELETE could be a substantial speedup.
+    -- See: https://github.com/yesodweb/yesod-scaffold/issues/201
     let escapedTables = map (connEscapeName sqlBackend . DBName) tables
         query = "TRUNCATE TABLE " ++ intercalate ", " escapedTables
     rawExecute query []