Thanks Pengcheng. It worked. Now I am curious to know, where is this data stored ? i.e. the data about the table statistics. For example, in Oracle we store these in DBA_TABLES and so on.
Regards Vivek ________________________________ From: Pengcheng Xiong <pxi...@apache.org> Sent: Thursday, February 9, 2017 7:12 AM To: user@hive.apache.org Subject: Re: Num Rows computed by EXPLAIN - Hive Did u run "analyze table emp compute statistics" before you run the explain? thanks. Pengcheng On Wed, Feb 8, 2017 at 9:29 PM, Vivek Sharma <vlsha...@hotmail.com<mailto:vlsha...@hotmail.com>> wrote: Hi, I am new to Hive (just few days of learning). I am an Oracle Performance Expert and am comparing the Explain feature of Hive with Oracle Explain Plan command. I have an Internal Table with around 100 Rows in it. However, the Explain command in Hive computes this as 33, which looks to be huge discrepancy and cause a performance issues (for a larger table). Wanted to know the internal calculations of Hive to come out with the NUM ROWS. The output is pasted below (The table actually has 100 Rows) : hive (vivek)> explain select country, empno from emp; OK Explain STAGE DEPENDENCIES: Stage-0 is a root stage STAGE PLANS: Stage: Stage-0 Fetch Operator limit: -1 Processor Tree: TableScan alias: emp Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE Column stats: NONE Select Operator expressions: country (type: string), empno (type: int) outputColumnNames: _col0, _col1 Statistics: Num rows: 33 Data size: 3501 Basic stats: COMPLETE Column stats: NONE ListSink Regards Vivek
