VACUUM operations not performing even after enabling predictive optimization

Create a new deletion operation to trigger VACUUM after enabling predictive optimization.

Written by Sahil Singh

Last published at: March 28th, 2025

Problem 

Predictive optimization does not trigger VACUUM even though it is enabled and there are old unreferenced files present in the Delta table. 

 

Cause

If the table with predictive optimization enabled has no active usage, predictive optimization does not see this table and previously deleted data.

 

Solution

Create a new deletion operation to trigger VACUUM after enabling predictive optimization. 

  1. Commit any operation that could result in unreferenced files to the table, such as DELETE or MERGE. This creates unreferenced file information to pass to predictive optimization as eligible for VACUUM.
  2. Wait for deletedFileRetentionDuration to pass. 
  3. Check that VACUUM has been executed. 

 

For more information, please review the Predictive optimization for Delta Lake (AWS | Azure) documentation.

 

Note

Once a table has usage, VACUUM is triggered seven days after predictive optimization is enabled.