Re: Read table rows in chunks - Mailing list pgsql-hackers

Hey,

I"m trying to read the rows of a table in chunks to process them in a background worker.

I want to ensure that each row is processed only once.

I was thinking of using the `SELECT * ... OFFSET {offset_size} LIMIT {limit_size}` functionality for this but I"m running into issues.

Some approaches I had in mind that aren't working out:

 - Try to use the transaction id to query rows created since the last processed transaction id 

      - It seems Postgres does not expose row transaction ids so this approach is not feasible

 - Rely on OFFSET / LIMIT combination to query the next chunk of data 

      - SELECT * does not guarantee ordering of rows so it's possible older rows repeat or newer rows are missed in a chunk

Can you please suggest any alternative to periodically read rows from a table in chunks while processing each row exactly once.

Thanks,

Sushrut