Re: postgresql Logical Replication Stream fails with “Database connection failed when reading from copy”

Hi,

Off the top of my head I don't have any advice. Can you try the latest
driver though and see if it still exists.

Are there any messages on the server saying that it closed the connection ?

Dave Cramer

davec(at)postgresintl(dot)com
www.postgresintl.com

On Mon, 3 Sep 2018 at 06:34, Jammie <shailesh(dot)jamloki(at)gmail(dot)com> wrote:

> Hi I am reading from logical replication stream continuously in infinite
> while loop. and I have another program that is continuously populating a
> table in the same database. I notice that after some time (around 5-10
> minutes). I always get the exception
>
> org.postgresql.util.PSQLException: Database connection failed when reading from copy
> at org.postgresql.core.v3.QueryExecutorImpl.readFromCopy(QueryExecutorImpl.java:1035)
> at org.postgresql.core.v3.CopyDualImpl.readFromCopy(CopyDualImpl.java:41)
> at org.postgresql.core.v3.replication.V3PGReplicationStream.receiveNextData(V3PGReplicationStream.java:155)
> at org.postgresql.core.v3.replication.V3PGReplicationStream.readInternal(V3PGReplicationStream.java:124)
> at org.postgresql.core.v3.replication.V3PGReplicationStream.read(V3PGReplicationStream.java:70)
> at com.datamirror.ts.scrapers.postgresqlscraper.PGStreamReceiver.main(PGStreamReceiver.java:60)
> Caused by: java.net.SocketException: Connection reset
> at java.net.SocketInputStream.read(SocketInputStream.java:220)
> at java.net.SocketInputStream.read(SocketInputStream.java:152)
> at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:140)
> at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:109)
> at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:67)
> at org.postgresql.core.PGStream.receiveChar(PGStream.java:293)
> at org.postgresql.core.v3.QueryExecutorImpl.processCopyResults(QueryExecutorImpl.java:1077)
> at org.postgresql.core.v3.QueryExecutorImpl.readFromCopy(QueryExecutorImpl.java:1033)
>
> Here is my sample program :
>
> import java.nio.ByteBuffer;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.SQLException;
> import java.util.Properties;
> import java.util.concurrent.TimeUnit;
>
> import org.postgresql.PGConnection;
> import org.postgresql.PGProperty;
> import org.postgresql.replication.LogSequenceNumber;
> import org.postgresql.replication.PGReplicationStream;
>
> public class PGStreamReceiver {
> public static void main(String[] args) {
> try {
> LogSequenceNumber startLsn = LogSequenceNumber.valueOf("0/2D8D0F0");
> String url = "jdbc:postgresql://localhost:5432/postgres"
> ;
> String user ="postgres";
> String password = "xxxx";
> Properties connectionProperties = new Properties();
>
> PGProperty.USER.set(connectionProperties, user);
> PGProperty.PASSWORD.set(connectionProperties, password);
> PGProperty.ASSUME_MIN_SERVER_VERSION.set(connectionProperties, PostgreSQLConstants.MINIMUM_SUPPORTED_POSTGRESQL_VERSION);
> PGProperty.REPLICATION.set(connectionProperties, PostgreSQLConstants.POSTGRESQL_REPLICATION_PROPERTY_VALUE);
> PGProperty.PREFER_QUERY_MODE.set(connectionProperties, PostgreSQLConstants.POSTGRESQL_REPLICATION_PREFERRED_QUERY_MODE);
> Connection postgresSQLConnection = DriverManager.getConnection(url, connectionProperties);
> PGConnection postgrePGConnectionWrapper = postgresSQLConnection.unwrap(PGConnection.class);
> PGReplicationStream stream = postgrePGConnectionWrapper.
> getReplicationAPI()
> .replicationStream()
> .logical()
> .withSlotName("pvn")
> .withStartPosition(startLsn)
> .withSlotOption(PostgreSQLConstants.INCLUDE_XID_IN_STREAM_CHANGES, true)
> .withSlotOption(PostgreSQLConstants.INCLUDE_TIMESTAMP_IN_STREAM_CHANGES, true)
> .withSlotOption(PostgreSQLConstants.EXCLUDE_EMPTY_TRANSACTION_IN_CHANGES, true)
> //.withStatusInterval(PostgreSQLConstants.SERVER_FEEDBACK_TIME_INTERVAL_IN_SECONDS, TimeUnit.SECONDS)
> .withStatusInterval(60, TimeUnit.SECONDS)
> .start();
> while(true)
> {
> ByteBuffer msg = stream.read();
> if(msg == null)
> {
> return;
> }
> int offset = msg.arrayOffset();
> byte[] source = msg.array();
> int length = source.length - offset;
> String logData = new String(source, offset, length);
> System.out.print("1");
> }
> } catch (SQLException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> }
>
> }
>
> Any help is appreciated !! I am using postgres JDBC driver 42.2.2.
> Reference:
>
> https://stackoverflow.com/questions/52147844/postgresql-logical-replication-stream-fails-with-database-connection-failed-whe
>
> Regards
> Shailesh
>