Safe Haskell	None
Language	Haskell2010

Data.MultiPool.Persist.Postgresql

Synopsis

initMultiPool :: (MonadLogger m, MonadUnliftIO m) => ConnectionString -> Int -> [(InstanceName SqlReadBackend, ConnectionString, Int)] -> m (MultiPool SqlBackend)
initMultiPool' :: (MonadLogger m, MonadUnliftIO m) => (MultiPool SqlBackend -> IO (Maybe (InstanceName SqlReadBackend))) -> ConnectionString -> Int -> [(InstanceName SqlReadBackend, ConnectionString, Int)] -> m (MultiPool SqlBackend)
runReadCurrent :: MonadUnliftIO m => MultiPool SqlBackend -> HashMap (InstanceName SqlReadBackend) LSN -> LSN -> ReaderT SqlReadBackend m a -> m a
getLastLSN :: MonadIO m => ReaderT SqlReadBackend m LSN
gatherLSNs :: MonadUnliftIO m => MultiPool SqlBackend -> m (HashMap (InstanceName SqlReadBackend) LSN)

Documentation

initMultiPool :: (MonadLogger m, MonadUnliftIO m) => ConnectionString -> Int -> [(InstanceName SqlReadBackend, ConnectionString, Int)] -> m (MultiPool SqlBackend) Source #

initMultiPool' Source #

Arguments

:: (MonadLogger m, MonadUnliftIO m)
=> (MultiPool SqlBackend -> IO (Maybe (InstanceName SqlReadBackend)))
-> ConnectionString	Primary connection string
-> Int	Max number of connections to primary instance
-> [(InstanceName SqlReadBackend, ConnectionString, Int)]	Replica connection details
-> m (MultiPool SqlBackend)

runReadCurrent :: MonadUnliftIO m => MultiPool SqlBackend -> HashMap (InstanceName SqlReadBackend) LSN -> LSN -> ReaderT SqlReadBackend m a -> m a Source #

Performs a read on the first replica found that sufficiently up-to-date with the given LSN. This function can be combined with gatherLSNs and some sort of caching mechanism to provide a simple way to scale out reads. An great article on this concept can be found here

If no replica is up-to-date with the given LSN, the primary instance will be used to run the query.

getLastLSN :: MonadIO m => ReaderT SqlReadBackend m LSN Source #

gatherLSNs :: MonadUnliftIO m => MultiPool SqlBackend -> m (HashMap (InstanceName SqlReadBackend) LSN) Source #