Paging with Oracle

Question

Something like this should work: From Frans Bouma's Blog

SELECT * FROM
(
    SELECT a.*, rownum r__
    FROM
    (
        SELECT * FROM ORDERS WHERE CustomerID LIKE 'A%'
        ORDER BY OrderDate DESC, ShippingDate DESC
    ) a
    WHERE rownum < ((pageNumber * pageSize) + 1 )
)
WHERE r__ >= (((pageNumber-1) * pageSize) + 1)

Ask Tom on pagination and very, very useful analytic functions.

This is excerpt from that page:

select * from (
    select /*+ first_rows(25) */
     object_id,object_name,
     row_number() over
    (order by object_id) rn
    from all_objects
)
where rn between :n and :m
order by rn;

In the interest of completeness, for people looking for a more modern solution, in Oracle 12c there are some new features including better paging and top handling.

Paging

The paging looks like this:

SELECT *
FROM user
ORDER BY first_name
OFFSET 5 ROWS FETCH NEXT 10 ROWS ONLY;

Top N Records

Getting the top records looks like this:

SELECT *
FROM user
ORDER BY first_name
FETCH FIRST 5 ROWS ONLY

Notice how both the above query examples have ORDER BY clauses. The new commands respect these and are run on the sorted data.

I couldn't find a good Oracle reference page for FETCH or OFFSET but this page has a great overview of these new features.

Performance

As @wweicker points out in the comments below, performance is an issue with the new syntax in 12c. I didn't have a copy of 18c to test if Oracle has since improved it.

Interestingly enough, my actual results were returned slightly quicker the first time I ran the queries on my table (113 million+ rows) for the new method:

• New method: 0.013 seconds.
• Old method: 0.107 seconds.

However, as @wweicker mentioned, the explain plan looks much worse for the new method:

• New method cost: 300,110
• Old method cost: 30

The new syntax caused a full scan of the index on my column, which was the entire cost. Chances are, things get much worse when limiting on unindexed data.

Let's have a look when including a single unindexed column on the previous dataset:

• New method time/cost: 189.55 seconds/998,908
• Old method time/cost: 1.973 seconds/256

Summary: use with caution until Oracle improves this handling. If you have an index to work with, perhaps you can get away with using the new method.

Hopefully I'll have a copy of 18c to play with soon and can update

Just want to summarize the answers and comments. There are a number of ways doing a pagination.

Prior to oracle 12c there were no OFFSET/FETCH functionality, so take a look at whitepaper as the @jasonk suggested. It's the most complete article I found about different methods with detailed explanation of advantages and disadvantages. It would take a significant amount of time to copy-paste them here, so I won't do it.

There is also a good article from jooq creators explaining some common caveats with oracle and other databases pagination. jooq's blogpost

Good news, since oracle 12c we have a new OFFSET/FETCH functionality. OracleMagazine 12c new features. Please refer to "Top-N Queries and Pagination"

You may check your oracle version by issuing the following statement

SELECT * FROM V$VERSION

Try the following:

SELECT *
FROM
  (SELECT FIELDA,
    FIELDB,
    FIELDC,
    ROW_NUMBER() OVER (ORDER BY FIELDC) R
  FROM TABLE_NAME
  WHERE FIELDA = 10
  )
WHERE R >= 10
AND R   <= 15;

via [tecnicume]