Hi all, and especially Quest devs, We ran into a failing Sqoop issue recently, while importing lots of data from an Oracle DB.
From the error below it looks Oracle is using transactional isolation for read consistency - but in our case, when pulling isolated rows (no inter-row dependencies) from a single table, that's not necessary, right? Is there any way to disable that? One alternative solution would be to provide the SCN_ASCENDING hint, as per: http://berxblog.blogspot.com/2009/01/avoid-ora-1555-in-long-running-queries.html This apparently causes Oracle to ignore the error and keep going, returning potentially inconsistent data - but for our case, that wouldn't matter. Any comments on this approach? Of course we'd need support from OraOop to be able to (optionally) specify that hint, I assume via oraoop-site.xml. Thanks, -- Ken ============================================================================================ 11/09/17 17:56:08 INFO oraoop.OracleConnectionFactory: Initializing Oracle session with SQL : alter session set time_zone = 'GMT' 11/09/17 17:56:08 INFO oraoop.OracleConnectionFactory: Initializing Oracle session with SQL : alter session disable parallel query 11/09/17 17:56:08 INFO oraoop.OracleConnectionFactory: Initializing Oracle session with SQL : alter session set "_serial_direct_read"=true 11/09/17 17:56:08 INFO oraoop.OracleConnectionFactory: Initializing Oracle session with SQL : alter session set tracefile_identifier=oraoop 11/09/17 17:56:08 INFO oraoop.OracleConnectionFactory: Initializing Oracle session with SQL : alter session set optimizer_index_cost_adj=10000 11/09/17 17:56:14 INFO oraoop.OraOopDataDrivenDBInputFormat: The table being imported by sqoop has 11403264 blocks that have been divided into 1392 chunks which will be processed in 16 splits. The chunks will be allocated to the splits using the method : ROUNDROBIN java.io.IOException: SQLException in nextKeyValue at com.cloudera.sqoop.mapreduce.db.DBRecordReader.nextKeyValue(DBRecordReader.java:246) at com.quest.oraoop.OraOopDBRecordReader.nextKeyValue(OraOopDBRecordReader.java:312) at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:455) at org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67) at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:143) at com.cloudera.sqoop.mapreduce.AutoProgressMapper.run(AutoProgressMapper.java:187) at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:646) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:322) at org.apache.hadoop.mapred.Child$4.run(Child.java:268) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1115) at org.apache.hadoop.mapred.Child.main(Child.java:262) Caused by: java.sql.SQLException: ORA-01555: snapshot too old: rollback segment number 3054 with name "_SYSSMU3054_4184535728$" too small at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:440) at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:396) at oracle.jdbc.driver.T4C8Oall.processError(T4C8Oall.java:837) at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:445) at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191) at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:523) at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:207) at oracle.jdbc.driver.T4CPreparedStatement.fetch(T4CPreparedStatement.java:1084) at oracle.jdbc.driver.OracleResultSetImpl.close_or_fetch_from_next(OracleResultSetImpl.java:359) at oracle.jdbc.driver.OracleResultSetImpl.next(OracleResultSetImpl.java:263) at com.cloudera.sqoop.mapreduce.db.DBRecordReader.nextKeyValue(DBRecordReader.java:235) ... 12 more -------------------------- Ken Krugler +1 530-210-6378 http://bixolabs.com custom big data solutions & training Hadoop, Cascading, Mahout & Solr
