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https://issues.apache.org/jira/browse/AVRO-261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12828615#action_12828615
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Thiruvalluvan M. G. commented on AVRO-261:
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bq. does wrapping these not affect performance? Many operations iterate over
fields or lookup enum symbols. The immutable wrapper adds another method call
to each such operation.
One of the heavy users of schema is GenericDatumReader (prior to AVRO-388). On
my machine the performance of AvroGenericReader went down by 8 - 15%, depending
on the kind of schema resolution used. Though the impact on GenericDatumReader
will come down with AVRO-388, other users such as GenericDatumWriter will get
affected.
I don't see an easy way out. In order to avoid exposing the collections
directly to the clients, we may add methods like iterator(), get() etc. in the
Schema itself. But then we'll have the very same problem as the unmodifiable
wrappers.
With this kind of performance impact I'm reluctant to push this patch.
On the issue of setProp(), will replacing it with addProp() (meaning one is
allowed to add new properties to a schema, but not remove or replace existing
properties) help? This is not quite immutability. But I don't think any code
will be affected because of additional properties added.
> Allow Schemas to be immutable
> -----------------------------
>
> Key: AVRO-261
> URL: https://issues.apache.org/jira/browse/AVRO-261
> Project: Avro
> Issue Type: New Feature
> Components: java
> Reporter: Kevin Oliver
> Assignee: Thiruvalluvan M. G.
> Priority: Minor
> Attachments: AVRO-261.patch
>
>
> It would be nice if there was the ability to have an immutable Schema in
> java.
> Without this, it makes sharing schemas risky. Also, with this, we could
> (lazily) cache the hashCode which is a fairly expensive operation today,
> especially on something like a record.
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