How do I delete records older than 90 days in QuestDB

Question

I am storing IoT sensor data streaming from mutltiple sources into a few tables in QuestDb and because of the huge size of data, I want to keep only the last 90 days. I can see a few ways on their documentation for deleting, but I don't want to truncate the table as I would lose latest records. Is there any way instead of making a backup and truncating tables to delete data older than 90 days?

Answer 1

The strategy here should be creating a table that is partitioned and then dropping partitions based on a time value relative to now. The table also has to have a designated timestamp. This example would perform that:

CREATE TABLE my_table (timestamp TIMESTAMP, x STRING) timestamp(timestamp) PARTITION BY DAY;

In your case, you want to drop partitions older than 90 days, you can do that with ALTER TABLE DROP PARTITION

ALTER TABLE my_table DROP PARTITION
WHERE timestamp < dateadd('d', -90, now())

It might be useful to know that you can also partition by MONTH or YEAR.

Beware this is destructive and QuestDB can't recover data that's been deleted in this way, either ensure you have a proper backup method in place or that you're certain you do not need the data any more. There are more details at the ALTER TABLE DROP PARTITION reference pages.

Edit: There is now dedicated docs for this on the Data retention page