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https://issues.apache.org/jira/browse/OFBIZ-5115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13540723#comment-13540723
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Leon edited comment on OFBIZ-5115 at 12/29/12 1:57 AM:
-------------------------------------------------------
Jacques,
We use OFBiz as the back-end framework of our LIMS (Laboratory Information
Management System). It requires very heavy data statistics. In this case, we
defined a static view entity to do some basic summary job and use "select" with
distinct options to get desired result data-set. The data itself is no problem,
but we found the total count it returned is always a little bigger than
expected.
After some research, we found the root cause: the SQL with group by implies to
select all the fields to be grouped by, that's why "count" and /or
"count(distinct)" does not work as usual. e.g.
SELECT COUNT(*) FROM POSTAL_ADDRESS GROUP BY COUNTRY_GEO_ID -> its count result
is same as SELECT COUNTRY_GEO_ID, COUNT(*) FROM POSTAL_ADDRESS GROUP BY
COUNTRY_GEO_ID. and,
SELECT COUNT(DISTINCT COUNTRY_GEO_ID) FROM POSTAL_ADDRESS GROUP BY
COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID -> its data set result size equals that
of SELECT COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID, COUNT(*) FROM POSTAL_ADDRESS
GROUP BY COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID.
was (Author: utcb):
Jacques,
We use OFBiz as the back-end framework of our LIMS (Laboratory Information
Management System). It requires very heavy data statistics. In this case, we
defined a static view entity to get some basic summary job and use "select"
with distinct options to get desired result data-set. The data itself is no
problem, but we found the total count it returned is always a little bigger
than expected.
After some research, we found the root cause: the SQL with group by implies to
select all the fields to be grouped by, that's why "count" and /or
"count(distinct)" does not work as usual. e.g.
SELECT COUNT(*) FROM POSTAL_ADDRESS GROUP BY COUNTRY_GEO_ID -> its count result
is same as SELECT COUNTRY_GEO_ID, COUNT(*) FROM POSTAL_ADDRESS GROUP BY
COUNTRY_GEO_ID. and,
SELECT COUNT(DISTINCT COUNTRY_GEO_ID) FROM POSTAL_ADDRESS GROUP BY
COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID -> its data set result size equals that
of SELECT COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID, COUNT(*) FROM POSTAL_ADDRESS
GROUP BY COUNTRY_GEO_ID, STATE_PROVINCE_GEO_ID.
> wrong COUNT DISTINCT if there's GROUP BY clause
> -----------------------------------------------
>
> Key: OFBIZ-5115
> URL: https://issues.apache.org/jira/browse/OFBIZ-5115
> Project: OFBiz
> Issue Type: Bug
> Components: framework
> Affects Versions: SVN trunk
> Reporter: Leon
> Priority: Minor
> Fix For: SVN trunk
>
> Attachments: OFBIZ-5115.patch
>
>
> if there's a "group by" and distinct find options set, then the count of
> select returned is always the total number of non-distinct.
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