wanghao created KYLIN-3934:
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Summary: sqoop import param '--null-string' result in null value
become blank string in hive table
Key: KYLIN-3934
URL: https://issues.apache.org/jira/browse/KYLIN-3934
Project: Kylin
Issue Type: Bug
Components: Others
Affects Versions: v2.6.0
Reporter: wanghao
when column value from jdbc is null, sqoop will write it into hive table with
blank string.
eg
jdbc:
A | B
1 | 1
2 | 2
a | null
hive table:
A | B
1 | 1
2 | 2
a |
because of this, when I use count(distinct B), it return 3, not 2, and it can
lead to other problems
{code:java}
String cmd = String.format(Locale.ROOT,
"%s/bin/sqoop import" + generateSqoopConfigArgString()
+ "--connect \"%s\" --driver %s --username %s --password %s --query \"%s AND
\\$CONDITIONS\" "
+ "--target-dir %s/%s --split-by %s --boundary-query \"%s\" --null-string '' "
+ "--fields-terminated-by '%s' --num-mappers %d",
sqoopHome, connectionUrl, driverClass, jdbcUser, jdbcPass, selectSql,
jobWorkingDir, hiveTable,
splitColumn, bquery, filedDelimiter, mapperNum);
{code}
the param '–null=string' should be '\\N' instead of blank string ''.
I resolved this problem by replace the param. But it needs be configured in
kylin.properties
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