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I’ve a PK constraint – a clustered index on two columns – which I am in the process of dropping. The command is still running after an hour. I would have thought that as I am just removing a constraint the operation would be nearly instantaneous. Can someone explain to me what is actually happening under the hood when I drop the PK?
Clustered index is not ‘just a constraint’, it’s a storage method.
When you drop it, your data are being reordered from clustered storage to heap storage
Other indexes are being updated to refer to
RID‘s instead ofPRIMARY KEYvalues.