Copyright	(c) James King 2020 2021
License	BSD3
Maintainer	james@agentultra.com
Stability	experimental
Portability	POSIX
Safe Haskell	None
Language	Haskell2010

Database.PostgreSQL.Replicant.Types.Lsn

Description

Log Sequence Number or LSN is a pointer to a place inside of a WAL log file. It contains the file name and an offset in bytes encoded in two parts.

LSNs can be serialized into 64-bit big-endian numbers in the binary protocol but are also represented textually in query results and other places.

This module follows a similar convention to many containers libraries and should probably be imported qualified to avoid name clashes if needed.

See: https://www.postgresql.org/docs/10/datatype-pg-lsn.html

Synopsis

data LSN = LSN {
- filepart :: !Int32
- offset :: !Int32
}
toInt64 :: LSN -> Int64
fromInt64 :: Int64 -> LSN
lsnParser :: Parser LSN
fromByteString :: ByteString -> Either String LSN
toByteString :: LSN -> ByteString
add :: LSN -> Int64 -> LSN
sub :: LSN -> Int64 -> LSN
subLsn :: LSN -> LSN -> Int64

Documentation

data LSN Source #

Constructors

LSN
Fields filepart :: !Int32 Filepart offset :: !Int32 Offset

Instances

Instances details

Eq LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods (==) :: LSN -> LSN -> Bool # (/=) :: LSN -> LSN -> Bool #
Ord LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods compare :: LSN -> LSN -> Ordering # (<) :: LSN -> LSN -> Bool # (<=) :: LSN -> LSN -> Bool # (>) :: LSN -> LSN -> Bool # (>=) :: LSN -> LSN -> Bool # max :: LSN -> LSN -> LSN # min :: LSN -> LSN -> LSN #
Show LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods showsPrec :: Int -> LSN -> ShowS # show :: LSN -> String # showList :: [LSN] -> ShowS #
ToJSON LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods toJSON :: LSN -> Value # toEncoding :: LSN -> Encoding # toJSONList :: [LSN] -> Value # toEncodingList :: [LSN] -> Encoding #
FromJSON LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods parseJSON :: Value -> Parser LSN # parseJSONList :: Value -> Parser [LSN] #
Serialize LSN Source #
Instance details Defined in Database.PostgreSQL.Replicant.Types.Lsn Methods put :: Putter LSN # get :: Get LSN #

toInt64 :: LSN -> Int64 Source #

Convert an LSN to a 64-bit integer

fromInt64 :: Int64 -> LSN Source #

Convert a 64-bit integer to an LSN

lsnParser :: Parser LSN Source #

fromByteString :: ByteString -> Either String LSN Source #

toByteString :: LSN -> ByteString Source #

Note that as of bytestring ~0.10.12.0 we don't have upper-case hex encoders but the patch to add them has been merged and when available we should switch to them

add :: LSN -> Int64 -> LSN Source #

Add a number of bytes to an LSN

sub :: LSN -> Int64 -> LSN Source #

Subtract a number of bytes from an LSN

subLsn :: LSN -> LSN -> Int64 Source #

Subtract two LSN's to calculate the difference of bytes between them.