Re: Proposed Resource Manager Changes

Simon Riggs <simon(at)2ndQuadrant(dot)com> wrote:

> I would like to make a simple change to Resource Manager code to
> introduce a plugin that can redefine or extend Rmgrs.

It looks very reasonable to me.

> * values 33-127 are available by centrally managed registration to help
> avoid conflicts in Postgres projects on pgfoundry
> * values 128+ are user defined

One thing to worry about is a confliction of RmgrId. We can check
conflictions in redo because rmgrs are actually registered, but
we might need to check conflictions even in a normal running.
Extensions that write own XLog record can use arbitrary RmgrIds without
restrictions. It would be safe if we check whether RmgrIds required by
extensions are actually unused.

For more safe, we could store signatures of extensions in control file.
We store mapping of RmgrId to signatures in it and checks no changes since
last shutdown. UUID types (128 bits) would be good for the signature.

Regards,
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ITAGAKI Takahiro
NTT Open Source Software Center