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From Anil <anilk...@gmail.com>
Subject Re: Range queries on indexed columns
Date Wed, 14 Jun 2017 12:20:51 GMT
Hi Team,

Can some help in understanding the below ? Thanks.

On 13 June 2017 at 11:07, Anil <anilklce@gmail.com> wrote:

> HI Team,
>
> I have a table TEST with a indexed column COL_A. Does the following query
> works ?
>
> select * from Test where COL_A > '1' and COL_A < '2' offset 10  ROWS FETCH
> NEXT 20 ROWS ONLY
>
> As per my understanding of distributed systems, the query is sent to all
> nodes and gets the 10 records from each node and return 10 (whatever
> returns first)
>
> as indexes are distributed, the above query may not return the records in
> paginated way without adding sort like below.
>
> select * from Test where COL_A > '1' and COL_A < '2' order by COL_A offset
> 10  ROWS FETCH NEXT 20 ROWS ONLY
>
> do you see any overhead of sort here ?
>
> Does it work in following way ?
>
> send the query to all nodes and get 10 (based on sorting) records and sort
> all results of each node at reducer and return final 10 .
>
> Sort should not have any overhead here as sort and filter is done on
> indexed column.
>
> Please correct me if i am wrong. thanks.
>
> Thanks
>
>

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