I have a delta table that is partitioned by Year, Date and month. I'm trying to merge data to this on all three partition columns + an extra column (an ID). My merge statement is below:

MERGE INTO delta.<path of delta table> oldData 
using df newData 
on oldData.year = '2023' and oldData.month = '10' and oldData.day = '12' and oldData.clientid=newData.clientid WHEN MATCHED THEN DELETE

When I do an explain on this query I get this plan:

== Physical Plan ==
Execute MergeIntoCommandEdge
   +- MergeIntoCommandEdge SubqueryAlias newData, SubqueryAlias oldData, Delta[version=4, ... , (((year#3761220 = 2023) AND (month#3761221 = 10)) AND ((day#3761222 = 12) AND (clientid#3761212 = clientid#3532751)))

This query runs for a long time considering I think the data I'm trying to process is small (less than 1M). Also based on this link I should see some sort of mention of partition in the physical plan but I don't. Any ideas why it seems that my merge statement is not using the partition when executing the merge statement?