LIMIT
and OFFSET
LIMIT
and OFFSET
allow you to retrieve just a portion of the rows that are generated by the rest of the query:
SELECT select_list
FROM table_expression
[ ORDER BY ... ]
[ LIMIT { number | ALL } ] [ OFFSET number ]
If a limit count is given, no more than that many rows will be returned (but possibly fewer, if the query itself yields fewer rows). LIMIT ALL
is the same as omitting the LIMIT
clause, as is LIMIT
with a NULL argument.
OFFSET
says to skip that many rows before beginning to return rows. OFFSET 0
is the same as omitting the OFFSET
clause, as is OFFSET
with a NULL argument.
If both OFFSET
and LIMIT
appear, then OFFSET
rows are skipped before starting to count the LIMIT
rows that are returned.
When using LIMIT
, it is important to use an ORDER BY
clause that constrains the result rows into a unique order. Otherwise you will get an unpredictable subset of the query's rows. You might be asking for the tenth through twentieth rows, but tenth through twentieth in what ordering? The ordering is unknown, unless you specified ORDER BY
.
The query optimizer takes LIMIT
into account when generating query plans, so you are very likely to get different plans (yielding different row orders) depending on what you give for LIMIT
and OFFSET
. Thus, using different LIMIT
/OFFSET
values to select different subsets of a query result will give inconsistent results unless you enforce a predictable result ordering with ORDER BY
. This is not a bug; it is an inherent consequence of the fact that SQL does not promise to deliver the results of a query in any particular order unless ORDER BY
is used to constrain the order.
The rows skipped by an OFFSET
clause still have to be computed inside the server; therefore a large OFFSET
might be inefficient.