PostgreSQL - Clustering never completes - long key?

I am having problems with clustering a table where the key consists of one char(23) field and two TimeStamp fields. The char(23) field contains Alpha-Numeric values. The clustering operation never finishes. I have let it run for 24 hours and it still did not finish.

Has anyone run into this kind of problem before? Is my theory that the reason is the long key field makes sense? We have dealt with much larger tables that do not have long keys and we have always been able to perform DB operations on them without any problem. That makes me think that it might have to do with the size of the key i开发者_JAVA技巧n this case.

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Cluster rewrites the table so it must wait on locks. It is possible that it is never getting the lock it needs. Why are you setting varchar(64000)? Why not just unrestricted varchar? And how big is this index?

If size is a problem it has to be based on the index size not the key size. I don't know what the effect of toasted key attributes is on cluster because these are moved into extended storage. TOAST might complicate CLUSTER and I have never heard of anyone clustering on a TOASTed attribute. It wouldn't make much sense to do so. TOASTing is necessary for any attribute more than 4k in size.

A better option is to create an index for the values without the possibly toasted value, and then cluster on that. That should give you something very close to what you'd get otherwise.