How Can I Optimize Pagination in PostgreSQL for Large Tables to Avoid OFFSET Bottlenecks?

Optimizing Pagination in PostgreSQL: Strategies to Overcome OFFSET Performance Issues

Using OFFSET with large PostgreSQL tables often leads to performance problems. Here are effective strategies to improve pagination efficiency:

Keyset Pagination: Leveraging Row Value Comparisons

Instead of relying on OFFSET, utilize row value comparisons for more efficient row skipping. This involves sorting your table by the relevant columns and using the last row's values from the previous page as the starting point for the next page's query.

<code class="language-sql">SELECT *
FROM big_table
WHERE (vote, id) > (vote_x, id_x)  -- Row value comparison
ORDER BY vote, id
LIMIT n;</code>

This method efficiently uses indexes on (vote, id) to filter results.

Indexed Row Number Approach (Read-Heavy Workloads)

For tables primarily used for reading, adding an indexed row number column provides a direct way to skip rows, eliminating the need for OFFSET. Note: This is not ideal for frequently updated tables.

<code class="language-sql">ALTER TABLE big_table ADD COLUMN row_number INT GENERATED ALWAYS AS IDENTITY PRIMARY KEY;
SELECT *
FROM big_table
WHERE row_number > x
LIMIT n;</code>

Important Considerations:

• ORDER BY Alignment: Ensure your ORDER BY clause aligns with the pagination direction.
• NULL Handling: Address NULL values using NOT NULL constraints or NULLS FIRST/LAST to avoid unexpected behavior.
• Further Reading: For in-depth information on keyset pagination and PostgreSQL performance optimization, explore resources like Markus Winand's blog.

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