Is there a limitation ?

Question

Hi,
Using the following query I got some strange error. Using max 5 queries everything works fine but adding more than 5 queries the sql stops to work and returns nothing at all.
WORKS:
select TWITTER_FILTER_NAME, DateAdd(minute,-2,System.TimeStamp) AS TWITTER_INTIME,System.TimeStamp AS TWITTER_OUTTIME,count(*) as TWITTER_NUMBER_POSTS from (
    SELECT 'ZURN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]ZURN%'
    union
    SELECT 'GIVN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]GIVN%'
    union
    SELECT 'SYNN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]SYNN%'
    union
    SELECT 'UHR' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]UHR%'
    union
    SELECT 'NOVN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]NOVN%'
    ) x
GROUP BY TumblingWindow(minute,2),TWITTER_FILTER_NAME
DOESNT WORK:
select TWITTER_FILTER_NAME, DateAdd(minute,-2,System.TimeStamp) AS TWITTER_INTIME,System.TimeStamp AS TWITTER_OUTTIME,count(*) as TWITTER_NUMBER_POSTS from (
    SELECT 'ZURN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]ZURN%'
    union
    SELECT 'GIVN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]GIVN%'
    union
    SELECT 'SYNN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]SYNN%'
    union
    SELECT 'UHR' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]UHR%'
    union
    SELECT 'NOVN' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]NOVN%'
    union
    SELECT 'NOVN2' as TWITTER_FILTER_NAME FROM twitterhubanalytics2 where text like '%[$]NOVN2%'   
     ) x
GROUP BY TumblingWindow(minute,2),TWITTER_FILTER_NAME
Any preview limitation ??
Markus
Markus Christen IT-Architect Microsoft Brasil http://blogs.technet.com/b/markuschristen/

Answer 1

I just wanted to mention that there is a much more efficient way to issue this query that will also skirt this limitation: use CASE rather than UNION:
SELECT
CASE
WHEN text like '%[$]ZURN%' THEN 'ZURN'
WHEN text like '%[$]GIVN%' THEN 'GIVN'
WHEN text like '%[$]SYNN%' THEN 'SYNN'
WHEN text like '%[$]UHR%' THEN 'UHR'
WHEN text like '%[$]NOVN2%' THEN 'NOVN2'
WHEN text like '%[$]NOVN%' THEN 'NOVN'
ELSE 'None'
END as TWITTER_FILTER_NAME
This query will run much faster. 
Thanks,
--Lev