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https://issues.apache.org/jira/browse/FLINK-8716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16370051#comment-16370051
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Aljoscha Krettek commented on FLINK-8716:
-----------------------------------------
The idea is that when a {{TypeSerializer}} signals that it requires migration
the backend would read all data with the old serialiser and re-encode with the
new serialiser. This way, we would always have data consistently encoded in the
backend.
The problem is that this isn't implemented yet so I think we cannot change how
the serialiser works currently.
> AvroSerializer does not use schema of snapshot
> ----------------------------------------------
>
> Key: FLINK-8716
> URL: https://issues.apache.org/jira/browse/FLINK-8716
> Project: Flink
> Issue Type: Bug
> Affects Versions: 1.4.0
> Reporter: Arvid Heise
> Priority: Major
>
> The new AvroSerializer stores the schema in the snapshot and uses it to
> validate compability.
> However, it does not use the schema of the snapshot while reading the data.
> This version will fail for any change of the data layout (so it supports more
> or less only renaming currently).
>
> [https://github.com/apache/flink/blob/f3a2197a23524048200ae2b4712d6ed833208124/flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java#L265]
> needs to use the schema from
>
> [https://github.com/apache/flink/blob/f3a2197a23524048200ae2b4712d6ed833208124/flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java#L188]
> as the first parameter. Accordingly, a readSchema field need to be set
> in #ensureCompatibility and relayed in #duplicate. Note that the readSchema
> is passed as the write schema parameter to the DatumReader, as it was the
> schema that was used to write the data.
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