phoenix-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Tao Xiao <xiaotao.cs....@gmail.com>
Subject Re: Can we create an secondary index for two or more columns?
Date Mon, 18 May 2015 01:17:21 GMT
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 <byh0831@gmail.com>:

> 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 <xiaotao.cs.nju@gmail.com>:
>
>> 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.
>>
>
>

Mime
View raw message