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https://issues.apache.org/jira/browse/KYLIN-4315?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17135098#comment-17135098
]
ASF GitHub Bot commented on KYLIN-4315:
---------------------------------------
RupengWang commented on pull request #1024:
URL: https://github.com/apache/kylin/pull/1024#issuecomment-643742229
## Design test cases
### Prepare test env
- create cube and build segment (2012-01-01 ~ 2013-01-01)
- dimension : LSTG_FORMAT_NAME, ops_region, part_dt
- measure : sum(price)
### Case-1
Make sure query-1 and query-2 has the same result.
- query-1 (Hive)
```sql
select LSTG_FORMAT_NAME, stddev_pop(SUM_M)
from (
select LSTG_FORMAT_NAME, ops_region, sum(price) as SUM_M
from KYLIN_SALES
where part_dt >= '2012-01-01' and part_dt < '2012-06-01'
group by LSTG_FORMAT_NAME, ops_region
) a
group by LSTG_FORMAT_NAME
order by LSTG_FORMAT_NAME
```
- query-2 (Kylin)
```sql
select LSTG_FORMAT_NAME, stddev_sum(ops_region, price)
from KYLIN_SALES
where part_dt >= '2012-01-01' and part_dt < '2012-06-01'
group by LSTG_FORMAT_NAME
order by LSTG_FORMAT_NAME
```
### Case-2
Make sure query-1 and query-2 has the same result.
- query-1 (Hive)
```sql
select stddev_pop(SUM_M)
from (
select LSTG_FORMAT_NAME, ops_region, sum(price) as SUM_M
from KYLIN_SALES
where part_dt >= '2012-01-01' and part_dt < '2012-06-01'
group by LSTG_FORMAT_NAME, ops_region
) a
```
- query-2(Kylin)
```sql
select stddev_sum(ops_region, price)
from KYLIN_SALES
where part_dt >= '2012-01-01' and part_dt < '2012-06-01'
```
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> Use metadata numRows in beeline client for quick row counting
> -------------------------------------------------------------
>
> Key: KYLIN-4315
> URL: https://issues.apache.org/jira/browse/KYLIN-4315
> Project: Kylin
> Issue Type: Improvement
> Components: Job Engine
> Reporter: Congling Xia
> Assignee: Congling Xia
> Priority: Major
> Fix For: v3.1.0
>
>
> Hi, I find that in `BeelineHiveClient`, method `getHiveTableRows` uses
> "select count(*) from <tb_name>" for table row counting. The method is
> invoked in flat intermediate table redistribution step in cube building.
> This stats can be loaded in metastore. It costs much less time than scanning
> all rows in Hive table. Since intermediate tables are created and inserted by
> Kylin, statistics will be automatically calculated and stored in metastore
> when
> `[hive.stats.autogather|https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.stats.autogather]`
> is enabled (which is the default setting for Hive).
> ref Hive wiki for more detail about `numRows` stats:
> [https://cwiki.apache.org/confluence/display/Hive/StatsDev#StatsDev-ExistingTables%E2%80%93ANALYZE]
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