DBinputFormat throws OutOfMemory exceptions when importing large tables from
PostgreSQL.
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Key: MAPREDUCE-2453
URL: https://issues.apache.org/jira/browse/MAPREDUCE-2453
Project: Hadoop Map/Reduce
Issue Type: Bug
Affects Versions: 0.21.0
Reporter: Tomoya Tainaka
Priority: Minor
DBinputFormat throws OutOfMemory exceptions and Java heap space errors when
importing large tables from PostgreSQL. This is because loading the whole
resultset into memory at the same time. As a consequence, the Java heap space
is exhausted.
Also, this problem happens with DataDrivenDBInputFormat.
I suggest utilizing "Fetch Size" parameter of JDBC within DBInputFormat.
I made patches as follows:
・modifying org.apache.hadoop.mapreduce.lib.db.DBInputFormat.
・creating org.apache.hadoop.mapreduce.PostgreSQLDBRecordReader.java.
・adding JDBC options of fetch size, which are setFetchSize() and
setAutoCommit().
I also modified DataDrivenDBinputFormat in the same way as DBInputFormat.
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