Thanks to Yuhao,
Is the column *M.C1* ignored when I invoke " create index idx on EXAMPLE
(M.C0, M.C1) " ?
Which of the following two solutions make sense?
solution a):
create index idx_1 on EXAMPLE (M.C0, M.C1)
create index idx_2 on EXAMPLE (M.C1, M.C0)
solution b):
create index idx_1 on EXAMPLE (M.C0)
create index idx_2 on EXAMPLE (M.C1)
2015-05-17 22:34 GMT+08:00 Yuhao Bi <[email protected]>:
> Hi Xiao Tao,
>
> You can create another secondary index on the same columns.
> create index another_index on EXAMPLE(M.C1, M.C0)
>
> After doing that, query b) should return faster.
>
> 2015-05-17 22:25 GMT+08:00 Tao Xiao <[email protected]>:
>
>> I tried to build secondary index for two columns, *M.C0* and *M.C1*:
>>
>> create index my_idx on EXAMPLE (M.C0, M.C1)
>>
>>
>> Then I tried to query by two indexes, respectively:
>>
>> a). select M.C0 from EXAMPLE where M.C0 = 'c0_00000001'
>> b). select M.C1 from EXAMPLE where M.C1 = 'c1_00000001'
>>
>> Query a) returned results in less than 0.3 second, and query b) returned
>> results in about 13 seconds. It seems that index was built for column
>> *M.C0*, not *M.C1*.
>>
>> Can we build secondary index for two or more columns ?
>>
>> Thanks.
>>
>
>
