Re: TABLESAMPLE usage

On 01/25/2016 05:09 AM, Tom Smith wrote:
> Hello:
>
> I have a big table with that is always appended with new data with a unique
> sequence id (always incremented, or timestamp as unique index) each row.
> I'd like to sample, say 100 rows out of say 1000 rows evently across all
> the rows,
> so that it would return rows of1, 101, 201, 301 you get idea.
> can TABLESAMPLE get one row for every 100 rows, based on the order
> of the rows added to table using the timestamp as already indexed/sorted
> sequence

No, TABLESAMPLE is intended to take a random sampling of the data using
various methods.

You're looking for something more like this:

select t.*
from generate_series(1, (select max(id) from t), 100) g
join t on t.id = g;
--
Vik Fearing +33 6 46 75 15 36
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support