Retrieving a fixed range of rows from Postgresql
The proper way to do this is using LIMIT and OFFSET.

Note that for this to work properly, your query will need an ORDER BY clause so that the rows are fetched in the same order each time.

Your first query would be:

SELECT qid,ansid,ans 
FROM table1 
WHERE askerid='something'
LIMIT 50 OFFSET 0


The second query would have an OFFSET of 50, as you want to skip the first 50 rows:

SELECT qid,ansid,ans
FROM table1 
WHERE askerid='something' 
LIMIT 50 OFFSET 50


The ORDER BY clause wants adding between the WHERE and LIMIT clauses.

The Postgres documentation on this is here, and mentions that this may not be performant for large OFFSET values. It will be ok for small-ish datasets if the ORDER BY column is indexed.