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https://issues.apache.org/jira/browse/KYLIN-2671?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053570#comment-16053570
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hongbin ma commented on KYLIN-2671:
-----------------------------------
please check org.apache.kylin.jdbc.KylinConnection#mockPreparedSignature,
currently the result of Kylin JDBC's
java.sql.Connection#prepareStatement(java.lang.String) method is mocked, which
means: You get a mocked statement metadata from prepareStatement before you
call java.sql.PreparedStatement#executeQuery(), it's okay if you use JDBC in
following way:
{code:java}
PreparedStatement statement = conn.prepareStatement("select LSTG_FORMAT_NAME,
sum(price) as GMV, count(1) as TRANS_CNT from test_kylin_fact " + "where
LSTG_FORMAT_NAME = ? group by LSTG_FORMAT_NAME");
statement.setString(1, "FP-GTC");
ResultSet rs = statement.executeQuery();
{code}
however it's not okay to:
{code:java}
PreparedStatement statement = conn.prepareStatement("select LSTG_FORMAT_NAME,
sum(price) as GMV, count(1) as TRANS_CNT from test_kylin_fact " + "where
LSTG_FORMAT_NAME = ? group by LSTG_FORMAT_NAME");
ResultSetMetaData metaData = statement.getMetaData();
// do something with metaData here will be problematical because
metaData is merely a mock
statement.setString(1, "FP-GTC");
ResultSet rs = statement.executeQuery();
{code}
> Speed up prepared query execution
> ---------------------------------
>
> Key: KYLIN-2671
> URL: https://issues.apache.org/jira/browse/KYLIN-2671
> Project: Kylin
> Issue Type: Improvement
> Reporter: hongbin ma
>
> BI tools use prepared query for function probing, kylin should not execute
> such queries in standard way because it is too costly.
> It's still worth mentioning standard "prepare-bindparameter-execute" way of
> PreparedStatement is still not supported. By now kylin only support Prepared
> Statements WITHOUT parameters.
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