On Wednesday, 19 May 2010 22:02:57 DT Piotr Wadas wrote:

Hello,

Does it make any sens to enable indexing of any attribute on read-only slave syncrepl replica?

Whether or not indexes make sense is not dependant on whether the LDAP service is a provider or consumer or not, but dependent on what searches the LDAP service serves.

For example, if a provider only provides writes and changes to consumers, but no searches from clients, it only makes sense to index attributes required for replication. If a consumer is run purely for making offline backups of the master (e.g. by slapcat), and serves no searches, it may also make sense to index only replication attributes.

I mean, isn't it just waste of resources, or, actually, is not a waste a resources at all, since replica is read-only and does not write anything anyway?

While a replica doesn't accept any changes from clients, it will write just as much as it's provider does on the same dataset, or it isn't doing a good job of replicating.

Typically, one normally configures the environment to direct read operations to slaves, so typically they have a higher read/write ratio, and it makes sense to have more indexes on slaves (the additional write IO for maintaining indexes is justified).

Regards, Buchan

--On Wednesday, May 19, 2010 11:02 PM +0200 DT Piotr Wadas pwadas@dtpw.pl wrote:

Hello,

Does it make any sens to enable indexing of any attribute on read-only slave syncrepl replica? I mean, isn't it just waste of resources, or, actually, is not a waste a resources at all, since replica is read-only and does not write anything anyway? This, I think, apply to any version of openldap.

Indexing attributes has to do with how the slave is queried. So, it depends how well you want the replica to perform while it is being "read". If you have no clients that query the replica, then I agree, there is no reason to index anything on it. I will note that syncrepl itself acts as an internal client, and there are some indices on the replica that help sync replication perform more quickly. But how badly you want to slow your replica down is of course entirely up to you. :)

--Quanah

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Quanah Gibson-Mount Principal Software Engineer Zimbra, Inc -------------------- Zimbra :: the leader in open source messaging and collaboration