<div dir="ltr">To implement Top, we use the JDBC method java.sql.Stetement.setMaxRows(). The LIMIT keyword is not standard ANSI SQL, so we do not use it. <div><br></div><div>If Kylin returns more rows than expected, it must be because setMaxRows is not implemented properly in the Kylin driver.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 28, 2016 at 5:40 AM, Jian Zhong <span dir="ltr"><<a href="mailto:zhongjian@apache.org" target="_blank">zhongjian@apache.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi all,<div><br></div><div>I'm trying to use Apache Kylin with Mondrian.</div><div><br></div><div>everything works fine before I meet TOP_N in kylin.I did some research but cannot fix that.</div><div><br></div><div>Hope someone give me a guide.</div><div><br></div><div><br></div><div>Say we have table KYLIN_SALES, and dimension SELLER_ID, measure column PRICE (sum), And I put SELLER_ID as <Attribute> in <Dimension>. the full Query SQL should be like this "SELECT SUM(PRICE),SELLER_ID from KYLIN_SALES group by SELLER_ID "</div><div>by default, Mondrian will generate sql like <font color="#ff0000">SQL1(attached below)</font> get all SELLER_ID info first. it's fine before meet TOP_N in Kylin</div><div><br></div><div>If SELLER_ID is a extra highCardinality column, and user only want to know TOP 10 SUM(PRICE) Sellers, Kylin will not store all distinct SELLER_ID in cuboid by default.</div><div>So Kylin will not support <font color="#ff0000">SQL1</font> , </div><div>But full sql <font color="#ff0000">SQL2</font> will be supported.</div><div><br></div><div>Is there any way to avoid MONDRIAN send <font color="#ff0000">SQL1</font> , but send SQL2 directly? </div><div><br></div><div><div><font color="#ff0000"><br>SQL1</font>:"SELECT SELLER_ID FROM KYLIN_SALES GROUP BY SELLER_ID"<br></div><div><font color="#ff0000">SQL2</font>:"SELECT SUM(PRICE),SELLER_ID from KYLIN_SALES group by SELLER_ID order by SUM(PRICE) limit 10"</div></div><div><br></div><div>About what's TopN in Kylin, see here</div><div><a href="http://kylin.apache.org/blog/2016/03/19/approximate-topn-measure/" target="_blank">http://kylin.apache.org/blog/<wbr>2016/03/19/approximate-topn-<wbr>measure/</a><br></div><div><br></div><div><br></div><div>Thank you!</div><div>Best Regards</div><div><br></div></div>
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