wal

Documentation

Index

• Constants
• Variables
• type ActionData
• type ActionKind
• type Begin
• type BinaryParser
  • func NewBinaryParser(byteOrder binary.ByteOrder) *BinaryParser
  • func (p *BinaryParser) ParseMessage(msg []byte, tx *Transaction) error
• type Column
  • func (c *Column) AssertValue(src []byte)
• type Commit
• type DataType
• type Delete
• type Insert
• type Origin
• type Parser
• type Relation
• type RelationColumn
• type RelationData
• type Transaction
  • func NewTransaction() *Transaction
  • func (w *Transaction) Clear()
  • func (w Transaction) CreateActionData(relationID int32, rows []TupleData, kind ActionKind) (a ActionData, err error)
  • func (w *Transaction) CreateEventsWithFilter(tableMap map[string][]string) []*event.Event
• type TupleData
• type Update

Constants

const (
	// CommitMsgType protocol commit message type.
	CommitMsgType byte = 'C'

	// BeginMsgType protocol begin message type.
	BeginMsgType byte = 'B'

	// OriginMsgType protocol original message type.
	OriginMsgType byte = 'O'

	// RelationMsgType protocol relation message type.
	RelationMsgType byte = 'R'

	// TypeMsgType protocol message type.
	TypeMsgType byte = 'Y'

	// InsertMsgType protocol insert message type.
	InsertMsgType byte = 'I'

	// UpdateMsgType protocol update message type.
	UpdateMsgType byte = 'U'

	// DeleteMsgType protocol delete message type.
	DeleteMsgType byte = 'D'

	// NewTupleDataType protocol new tuple data type.
	NewTupleDataType byte = 'N'

	// TextDataType protocol test data type.
	TextDataType byte = 't'

	// NullDataType protocol NULL data type.
	NullDataType byte = 'n'

	// ToastDataType protocol toast data type.
	ToastDataType byte = 'u'
)

Variables

var (
	ErrMessageLost        = errors.New("messages are lost")
	ErrEmptyMessage       = errors.New("empty WAL message")
	ErrUnknownMessageType = errors.New("unknown message type")
)

Types

type ActionData

type ActionData struct {
	Schema  string
	Table   string
	Kind    ActionKind
	Columns []Column
}

ActionData kind of WAL message data.

type ActionKind

type ActionKind string

ActionKind kind of action on WAL message.

const (
	ActionKindInsert ActionKind = "INSERT"
	ActionKindUpdate ActionKind = "UPDATE"
	ActionKindDelete ActionKind = "DELETE"
)

kind of WAL message.

type Begin

type Begin struct {
	// Identifies the message as a begin message.
	LSN int64
	// Commit timestamp of the transaction.
	Timestamp time.Time
	// 	Xid of the transaction.
	XID int32
}

Begin message format.

type BinaryParser

type BinaryParser struct {
	// contains filtered or unexported fields
}

BinaryParser represent binary protocol parser. WAL 二进制解析器

func NewBinaryParser

func NewBinaryParser(byteOrder binary.ByteOrder) *BinaryParser

NewBinaryParser create instance of binary parser.

func (*BinaryParser) ParseMessage

func (p *BinaryParser) ParseMessage(msg []byte, tx *Transaction) error

ParseMessage parse postgres WAL message. 解析 WAL 消息

type Column

type Column struct {
	// contains filtered or unexported fields
}

Column of the table with which changes occur.

func (*Column) AssertValue

func (c *Column) AssertValue(src []byte)

AssertValue converts bytes to a specific type depending on the type of this data in the database table.

type Commit

type Commit struct {
	// Flags; currently unused (must be 0).
	Flags int8
	// The LSN of the commit.
	LSN int64
	// The end LSN of the transaction.
	TransactionLSN int64
	// Commit timestamp of the transaction.
	Timestamp time.Time
}

Commit message format.

type DataType

type DataType struct {
	// ID of the data type.
	ID int32
	// Namespace (empty string for pg_catalog).
	Namespace string
	// name of the data type.
	Name string
}

DataType path of WAL message data.

type Delete

type Delete struct {
	/// ID of the relation corresponding to the ID in the relation message.
	RelationID int32
	// Identifies the following TupleData submessage as a key.
	KeyTuple bool
	// Identifies the following TupleData message as a old tuple.
	OldTuple bool
	// TupleData message part representing the contents of new tuple.
	Row []TupleData
}

Delete message format.

type Insert

type Insert struct {
	/// ID of the relation corresponding to the ID in the relation message.
	RelationID int32
	// Identifies the following TupleData message as a new tuple.
	NewTuple bool
	// TupleData message part representing the contents of new tuple.
	Row []TupleData
}

Insert message format.

type Origin

type Origin struct {
	// The LSN of the commit on the origin server.
	LSN int64
	// name of the origin.
	Name string
}

Origin message format.

type Parser

type Parser interface {
	ParseMessage([]byte, *Transaction) error
}

Parser WAL 消息解析器接口

type Relation

type Relation struct {
	// ID of the relation.
	ID int32
	// Namespace (empty string for pg_catalog).
	Namespace string
	// Relation name.
	Name string
	// Replica identity setting for the relation (same as relreplident in pg_class).
	Replica int8
	Columns []RelationColumn
}

Relation message format.

type RelationColumn

type RelationColumn struct {
	// Flags for the column which marks the column as part of the key.
	Key bool
	// name of the column.
	Name string
	// ID of the column's data type.
	TypeID int32
	// valueType modifier of the column (atttypmod).
	ModifierType int32
}

RelationColumn path of WAL message data.

type RelationData

type RelationData struct {
	Schema  string
	Table   string
	Columns []Column
}

RelationData kind of WAL message data.

type Transaction

type Transaction struct {
	LSN           int64
	BeginTime     *time.Time
	CommitTime    *time.Time
	RelationStore map[int32]RelationData
	Actions       []ActionData
}

Transaction transaction specified WAL message.

func NewTransaction

func NewTransaction() *Transaction

NewTransaction create and initialize new WAL transaction.

func (*Transaction) Clear

func (w *Transaction) Clear()

Clear transaction data.

func (Transaction) CreateActionData

func (w Transaction) CreateActionData(
	relationID int32,
	rows []TupleData,
	kind ActionKind,
) (a ActionData, err error)

CreateActionData create action from WAL message data.

func (*Transaction) CreateEventsWithFilter

func (w *Transaction) CreateEventsWithFilter(tableMap map[string][]string) []*event.Event

CreateEventsWithFilter filter WAL message by table, action and create events for each value.

type TupleData

type TupleData struct {
	Value []byte
}

TupleData path of WAL message data.

type Update

type Update struct {
	/// ID of the relation corresponding to the ID in the relation message.
	RelationID int32
	// Identifies the following TupleData submessage as a key.
	KeyTuple bool
	// Identifies the following TupleData message as a old tuple.
	OldTuple bool
	// Identifies the following TupleData message as a new tuple.
	NewTuple bool
	// TupleData message part representing the contents of new tuple.
	Row []TupleData
	// TupleData message part representing the contents of the old tuple or primary key.
	//Only present if the previous 'O' or 'K' part is present.
	OldRow []TupleData
}

Update message format.