Database.PostgreSQL.Replicant

Connect to a PostgreSQL server as a logical replication client and receive changes.

The basic API is this:

  withLogicalStream defaultSettings $ change -> do
    print change
    catch err -> do
      show err

This is a low-level library meant to give the primitives necessary to library authors to add streaming replication support. The API here to rather simplistic but should be hooked up to something like conduit to provide better ergonomics.

Documentation

withLogicalStream :: PgSettings -> (Change -> IO a) -> IO ()

Connect to a PostgreSQL database as a user with the replication attribute and start receiving changes using the logical replication protocol. Logical replication happens at the query level so the changes you get represent the set of queries in a transaction: insert, update, and delete.

This function will create the replication slot, if it doesn't exist, or reconnect to it otherwise and restart the stream from where the replication slot left off.

This function can throw exceptions in IO and shut-down the socket in case of any error.

data PgSettings

Constructors

PgSettings

Fields

• pgUser :: String
• pgDbName :: String
• pgHost :: String
• pgPort :: String
• pgSlotName :: String
• pgUpdateDelay :: String

  Controls how frequently the primaryKeepAlive thread updates PostgresSQL in ms

Instances

Eq PgSettings

Defined in Database.PostgreSQL.Replicant

Methods

(==) :: PgSettings -> PgSettings -> Bool

(/=) :: PgSettings -> PgSettings -> Bool

Show PgSettings

Defined in Database.PostgreSQL.Replicant

Methods

showsPrec :: Int -> PgSettings -> ShowS

show :: PgSettings -> String

showList :: [PgSettings] -> ShowS