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From James Taylor <jamestay...@apache.org>
Subject Re: smarter using of index while querying?
Date Tue, 10 May 2016 06:56:29 GMT
Please read the following and hopefully it will answer your questions:
https://phoenix.apache.org/secondary_indexing.html#Index_Usage

On Mon, May 9, 2016 at 11:36 PM, 金砖 <jinzhuan@wacai.com> wrote:

> hi, I'm using phoenix-4.7,  and I found phoenix did not use index
> efficiently enough.
> Can phoenix optimize more for this situation?
>
> EX:
>
> table:
>
>     create table t (pk varchar primary key, name varchar, age
> unsigned_int);
>
> and create 2 index on it:
>      create index name on t (name);
>      create index age on t (age);
>
>
> * problem1:  select * from table did not use index, instead  did full scan
> on table.*
>
> 0: jdbc:phoenix:localhost> explain select * from t where name = 'name';
> +-------------------------------------------------------------+
> |                            PLAN                             |
> +-------------------------------------------------------------+
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN FULL SCAN OVER T  |
> |     SERVER FILTER BY NAME = 'name'                          |
> +-------------------------------------------------------------+
>
>
> *problem2:  when selecting more than 1 field,  neither index will be used.
> *
>
> 0: jdbc:phoenix:localhost> explain select name from t where name = 'name'
> and age > 1;
> +-------------------------------------------------------------+
> |                            PLAN                             |
> +-------------------------------------------------------------+
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN FULL SCAN OVER T  |
> |     SERVER FILTER BY (NAME = 'name' AND AGE > 1)            |
> +-------------------------------------------------------------+
>
>
> 0: jdbc:phoenix:localhost> explain select age from t where name = 'name'
> and age > 1;
> +-------------------------------------------------------------+
> |                            PLAN                             |
> +-------------------------------------------------------------+
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN FULL SCAN OVER T  |
> |     SERVER FILTER BY (NAME = 'name' AND AGE > 1)            |
> +-------------------------------------------------------------+
>
>

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