indexing - multple indexes same column sql -
for db2 database, consider table tbl
(cola
, colb
, colc
) , queries as
select * tbl tbl.cola = 1234. select * tbl tbl.cola =1234 , tbl.colb = 73874
will if create 2 indexes i) on cola
ii) composite - cola,colb
if above sql's accessed have 2 indexes above. optemizer pick correct index based on query. thanks,
you need index (ii). composite index used whenever search data in prefix of columns. index on cola,colb,colc,cold
used when search cola
, cola , colb
, cola, colb, , colc
, , cola, colb, colc, , cold
.
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