Steve Yang created HADOOP-13619:
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Summary: missing data when reading avro file
Key: HADOOP-13619
URL: https://issues.apache.org/jira/browse/HADOOP-13619
Project: Hadoop Common
Issue Type: Bug
Components: fs/swift
Affects Versions: 2.6.0
Environment: Linux EL6
Reporter: Steve Yang
library used: org.apache.hadoop:hadoop-openstack:2.6.0
We are loading avro files from Oracle Storage Service server (i.e., Swift
server) into Spark DataFrame object through the Spark Data Source API. For
example:
return hiveCtx.read().format("com.databricks.spark.avro").load(objectName);
The number of records is less than the actual record count in the avro file
when reading the avro file from Storage Service server using OpenStack Swift
API.
If we run a SQL on top of the returned data frome like "select count(*) as C1
from <temp table>" we can see the record count is smaller when reading the same
avro file from local file system.
For a large avro file (awclassic.avro, 105M) the count is always wrong (42451
records vs. 60855). From the log file we can see the reading os the file is
splitted into 4:
2016-09-01 14:18:27 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/awclassic.avro:100663296+10044747
2016-09-01 14:18:27 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/awclassic.avro:33554432+33554432
2016-09-01 14:18:27 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/awclassic.avro:0+33554432
2016-09-01 14:18:27 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/awclassic.avro:67108864+33554432
For a smaller avro file (wine.avro, 19M) the count sometimes is correct (57076
records) and sometimes wrong (26999 records). Run the same spark SQL 10 times
back-to-back produces the following record count results:
run 1: 26999
run 2: 26999
run 3: 57076
run 4: 57056
run 5: 57076
run 6: 26999
run 7: 57076
run 8: 57076
run 9: 57076
run 10: 57076
For this wine.avro test case there are two splits:
2016-08-31 17:42:32 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/wine.avro:9965269+9965270
2016-08-31 17:42:32 INFO HadoopRDD:59 - Input split:
swift://qaTestData.oracleswift/testAvro/wine.avro:0+9965269
I will attach a zip file containing the two avro files in question and the
debugged log file section of reading wine.avro file - one with successful
reading(C4.ok) and one with missing record reading(C5.miss).
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