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From Christoph Kiehl <christ...@sulu3000.de>
Subject Consistency check of indexes takes to long
Date Tue, 14 Aug 2007 08:47:59 GMT
Hi,

we've got very big indexes/workspaces on our production servers which have from 
3,000,000 to 8,000,000 nodes and are still growing because of creation of 
versions and adding new nodes.
When it happens that the VM in which Jackrabbit lives in crashes during a write 
operation, Jackrabbit nicely applies the redo log on a restart which gets done 
quite quick but then starts its consistency check. This check takes from 30 
minutes to 2 hours depending on the repository. In this time our application is 
offline which we would of course like to avoid ;) Our system uses a bundle 
oracle pm which probably doesn't make things better.
I had a quick glance at the consistency check code and it seems like there is 
nothing that could be substantially optimized in that place. I thought it might 
be possible to just include those index segments that where used while replaying 
the redo log but as the consistency check works this is impossible.
I think the only way to fasten startup is to avoid the occurrence of the errors 
that the check is checking for at all. Since the redo log mechanism seems quite 
good I'm not sure if those errors (MissingAncestor, MultipleEntries, 
NodeDeleted, UnknownParent) can still occur. Could you maybe elaborate on the 
situations where you expect those errors to arise?
For now I'm thinking about disabling consistency checks at all by default and 
run them in a maintenance window at night. Unfortunately this might be a bit 
dangerous if parts of the application rely on certain nodes to be found by 
queries :/
WDYT?

Cheers,
Christoph


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