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https://issues.apache.org/jira/browse/SPARK-19655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15873093#comment-15873093
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hosein edited comment on SPARK-19655 at 2/18/17 10:36 AM:
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I have a Vertica database with 100 million rows and I run this code in spark:
########################
df = spark.read.format("jdbc").option("url" ,
vertica_jdbc_url).option("dbtable", 'test_table')
.option("user", "spark_user").option("password" , "password").load()
result = df.filter(df['id'] > 100).count()
print result
########################
I monitor queries in Vertica and spark code generates this query in Vertica:
SELECT 1 FROM test_table WHERE ("int_id" > 100)
this query returns about 100 million "1" and I think this is not suitable
was (Author: hosein_ey):
I have a Vertica database with 100 million rows and I run this code in spark:
df = spark.read.format("jdbc").option("url" ,
vertica_jdbc_url).option("dbtable", 'test_table')
.option("user", "spark_user").option("password" , "password").load()
result = df.filter(df['id'] > 100).count()
print result
I monitor queries in Vertica and spark code generates this query in Vertica:
SELECT 1 FROM test_table WHERE ("int_id" > 100)
this query returns about 100 million "1" and I think this is not suitable
> select count(*) , requests 1 for each row
> -----------------------------------------
>
> Key: SPARK-19655
> URL: https://issues.apache.org/jira/browse/SPARK-19655
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.1.0
> Reporter: hosein
> Priority: Minor
>
> when I want query select count( * ) by JDBC and monitor queries in database
> side, I see spark requests: select 1 for destination table
> it means 1 for each row and it is not optimized
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