RE: SQL Select Statement Woes

["Elvis Budimlic" <ebudimlic@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Prior to V5R4, LIKE clause goes down CQE path.  If you take it out, perhaps
it goes down SQE path and happens to perform better.

Another possibility is that it uses an index in one case and not another. 
It is possible for query optimizer to use an index over a literal with
trailing wildcard, but you're using upper & lower case and that is not
possible for both cases.  
If you use UPPER, it'll definitely go down CQE path, and may (highly
unlikely) use an index.

There are other possibilities too... Visual Explain is your friend.

Elvis

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-----Original Message-----
Subject: SQL Select Statement Woes

My apologies in advance for the long post.......I hope my question can be
understood........here goes!.....

Our users use ShowcaseQuery 7.0.  Some of the users run queries that take an
excessive amount of time to run (I guess this always the case when user have
the ability to run queries!).  At any rate, I have been asked to analyze
some of the queries and see where they went astray.   So far, I have had
good luck identifying and correcting the issues, but the SQL statement
listed below has me stumped.  This query is realy quite simple, but takes
over two hours to run!  As an experiment, I wrote an equivalent RPG program
and it takes a second or two to run!  That tells me that something is wrong
with this statement.  Throught trial and error, I have found that if I
remove "AND ( FOINSNAME LIKE 'HEALTHSP%' OR FOINSNAME LIKE 'healthsp%'" from
the select statement, then it runs in a second or two as well.  With this
statement, it wants to build an access path over SCHDETAIL (a 12 million
record file).  I should add that with this statement removed, 25 records are
returned.  Of these 2
 5, about 20 would have been eliminated with the offending statement
included.  I would have thought that this selection would have been done
after all of the other selections......so why is it trying to build an
access path?  BTW, I have run in debug and no access paths are suggested.

Thanks,

Joe

****************************************************************************
************
SELECT 
	DEPTDESC,
	PROVNAME,
	APPTDATE,
	CATMNE,
	PRVTYPEMNE,
	MRN,
	PATLNAME,
	PATFNAME,
	PATHOMEPH,
	PATWORKPH,
	SCHEDDATE,
	SCHEDINITS,
	CASE 
		WHEN ( FOEXPDATE = '0001-01-01' ) THEN ( ' ' ) 
		ELSE ( CONVERT ( FOEXPDATE, SQL_CHAR ) ) 
	END AS FOEXPDATE,
	"CASE" AS CCASE,
	FOINSNAME 
FROM 
	WARESCHED.SCHDETAIL SCHDETAIL,  
	WARESCHED.SCHDEPT SCHDEPT,  
	WAREHOUSE.PATHEADER PATHEADER,  
	WAREHOUSE.PATFOLOWUP PATFOLOWUP,  
	WARESCHED.SCHPROVDRS SCHPROVDRS,  
	WARESCHED.SCHCATEGRY SCHCATEGRY,  
	WARESCHED.SCHPROVTYP SCHPROVTYP 
WHERE 
	SCHDETAIL.SCHDEPT = SCHDEPT.DEPTNUM
	AND SCHDETAIL.PATMRN = PATHEADER.MRN
	AND PATHEADER.FSC1CD = PATFOLOWUP.FOFSC
	AND PATHEADER.MRN = PATFOLOWUP.FOMRN
	AND SCHDETAIL.PROVIDER = SCHPROVDRS.PROVNUM
	AND SCHDETAIL.CATEGORY = SCHCATEGRY.CATNUM
	AND SCHDETAIL.SCHDEPT = SCHPROVTYP.PRVTYPEDEP
	AND SCHDETAIL.PROVIDER = SCHPROVTYP.PRVTYPEPRV
	AND SCHDETAIL.TYPE = SCHPROVTYP.PRVTYPETYP
	AND(APPTDATE = date( Case when DAYOFWEEK( CURDATE( ) ) = 6 Then
days( CURDATE( ) ) + 3 Else days( CURDATE( ) ) + 1 End )
	AND STATUS NOT IN( 'CANCELLED', 'BUMPED' )
	AND SCHDEPT <> 3700
	AND PROVIDER NOT IN( 1870, 931, 3058, 1554, 1071, 3689, 1415, 2947,
2537, 2731, 3195, 1537, 2025, 530, 1620, 2426, 3040, 3316, 1708, 2977, 1558,
10238 )
	AND DEPTANCIL = 'N'
	AND DEPTRESOUR = 'N'
	AND ( FSC1INSCD IN( 'SF', 'HPM', 'HPA', 'TOH' )
	OR ( FSC1INSCD = 'CMO'
	AND ( FOINSNAME LIKE 'HEALTHSP%'
	OR FOINSNAME LIKE 'healthsp%')))) 
ORDER BY 
	1, 
	6, 
	3