PostgreSQL Tip: Dropped Columns Still Count Toward the Limit!

Quick PostgreSQL Tip: Dropped Columns Still Count Toward the Limit!

If you've ever had to drop and add columns in a PostgreSQL table, here’s something you might not know—dropped columns don't actually get deleted from the table's storage. They just become invisible to queries, but they still count towards the column limit.

PostgreSQL has a column limit of 1600 columns per table, and if you're constantly adding and dropping columns during migrations or updates, you might hit this limit without realizing it.

So, if you encounter issues with not being able to add more columns, even though you have only five or six visible ones, it's likely because of these "hidden" dropped columns.

How to fix this:

1. Recreate the table: This is the best way to reset the column count. Just create a new table, move the data over, and drop the old one. It’ll clear out all those hidden columns.
2. Vacuum and Reindex: This won’t remove dropped columns, but it helps optimize your table if you want to reclaim space.

If you’re running into this issue, it’s a good idea to think about your table design and see a better way to handle things.

Does anyone else run into this problem or have other solutions? Drop a comment and let’s chat!

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