sql - DB2 query optimization; LIKE alternative -


bare me sql not strong point:

i'm looking wildcard search i'm noticing performance degradation on particular strings(those return large number filtering down few).

select       tbl_1.key            , tbl_1.userid            , tbl_1.domain             , tbl_2.*            , tbl_3.*            , tbl_4.*         , tbl_1             , tbl_2                             , tbl_3                                , tbl_4            tbl_1.key                   =      tbl_2.key ,          tbl_1.key                   =      tbl_3.key ,          tbl_1.key                   =      tbl_4.key  ,          upper(tbl_1.userid)           'string%'  ,          upper(tbl_1.domain)           'string%'  ,          tbl_3.crit1                 =      ''   ,          tbl_3.crit2                 in     ('') ,          tbl_4.crit3                 =      ''

essentially i'm returning individual profile based on email address , domain wildcards filtering. there's index on tbl_1 consisting of key, userid, , domain. i'm trying avoid table scan , use index'd fields. db2 not seem index supported. appreciated; thanks.

the upper() may problem...not sure db2 luw @ least in db2 ibm be. "right" way case insensitive search case insensitive collating sequence or derived index.

a derived index: 

create index myindex on mytable (upper(userid))

on db2 ibm i, can use case insensitive collating sequence setting 

set option srtseq = *langidshr

note, have have *langidshr set when issue create index myindex on mytable (userid) , when doing select.


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