WalPositionLocator (Debezium Connector for PostgreSQL 1.7.2.Final API)

java.lang.Object
- io.debezium.connector.postgresql.connection.WalPositionLocator

```
public class WalPositionLocator
extends Object
```
This class is responsible for finding out a LSN from which Debezium should resume streaming after connector restarts. The LSNs are not guaranteed to be ordered in the WAL. LSN of commits are ordered and LSNs inside a transaction are ordered. It is thus necessary to find out the beginning of the unprocessed transaction and the LSN from which the streaming should start.

Author:

Jiri Pechanec

Field Summary

Fields
Modifier and Type	Field	Description
`private Lsn`	`firstLsnReceived`
`private Lsn`	`lastCommitStoredLsn`
`private Lsn`	`lastEventStoredLsn`
`private static org.slf4j.Logger`	`LOGGER`
`private Lsn`	`lsnAfterLastEventStoredLsn`
`private boolean`	`passMessages`
`private Lsn`	`startStreamingLsn`
`private boolean`	`storeLsnAfterLastEventStoredLsn`
`private Lsn`	`txStartLsn`

Constructor Summary

Constructors
Constructor Description

WalPositionLocator()

WalPositionLocator(Lsn lastCommitStoredLsn, Lsn lastEventStoredLsn)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`enableFiltering()`	Enables filtering of message LSNs based on calculated position.
`Lsn`	`getLastEventStoredLsn()`
`Optional<Lsn>`	`resumeFromLsn(Lsn currentLsn, ReplicationMessage message)`
`boolean`	`searchingEnabled()`
`boolean`	`skipMessage(Lsn lsn)`	Decides whether the message with given LSN should be removed or not based on previously located LSN point.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

LOGGER

private static final org.slf4j.Logger LOGGER

lastCommitStoredLsn
```
private final Lsn lastCommitStoredLsn
```

lastEventStoredLsn
```
private final Lsn lastEventStoredLsn
```

txStartLsn
```
private Lsn txStartLsn
```

lsnAfterLastEventStoredLsn
```
private Lsn lsnAfterLastEventStoredLsn
```

firstLsnReceived
```
private Lsn firstLsnReceived
```

passMessages
```
private boolean passMessages
```

startStreamingLsn
```
private Lsn startStreamingLsn
```

storeLsnAfterLastEventStoredLsn

private boolean storeLsnAfterLastEventStoredLsn

Constructor Detail

WalPositionLocator

public WalPositionLocator(Lsn lastCommitStoredLsn,
                          Lsn lastEventStoredLsn)

WalPositionLocator
```
public WalPositionLocator()
```

Method Detail
- resumeFromLsn
```
public Optional<Lsn> resumeFromLsn(Lsn currentLsn,
                                   ReplicationMessage message)
```
  Returns:
  
  the first LSN from which processing should be started or empty if the position has not been found yet
- skipMessage
```
public boolean skipMessage(Lsn lsn)
```
  Decides whether the message with given LSN should be removed or not based on previously located LSN point.
  
  Parameters:
  
  lsn -
  
  Returns:
  
  true if the message should be skipped, false otherwise
- enableFiltering
```
public void enableFiltering()
```
  Enables filtering of message LSNs based on calculated position.
- searchingEnabled
```
public boolean searchingEnabled()
```
  Returns:
  
  true if searching of WAL position should be executed
- getLastEventStoredLsn
```
public Lsn getLastEventStoredLsn()
```
- toString
```
public String toString()
```
  Overrides:
  
  toString in class Object