[jira] [Commented] (CASSJAVA-4) UDT codec decode is too restrictive in decoding of unknown fields

["Dmitry Konstantinov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSJAVA-4?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17910313#comment-17910313 ] 

Dmitry Konstantinov commented on CASSJAVA-4:
--------------------------------------------

closing as duplicate, https://github.com/apache/cassandra-java-driver/pull/1635 has been merged.

> UDT codec decode is too restrictive in decoding of unknown fields
> -----------------------------------------------------------------
>
>                 Key: CASSJAVA-4
>                 URL: https://issues.apache.org/jira/browse/CASSJAVA-4
>             Project: Apache Cassandra Java driver
>          Issue Type: Bug
>          Components: Core
>            Reporter: Dmitry Konstantinov
>            Assignee: Dmitry Konstantinov
>            Priority: Normal
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> The current UDT code logic in driver 4.x expects the number of UDT fields exactly equal to the number of fields in the schema version used to create the codec.
> As a result it makes applications less friendly to a live upgrade logic when we change DB schema and do a rolling restart of applications to switch from an old app version to a new one. In this scenario we can add a new field to UDT (backward compatible change) and a new application version can write this UDT with a new field filled but the old application version will fail to decode such UDT with the extra unknown field.
> Driver 3.x UDT codec has a different behaviour - the UDT codec logic reads known UDT fields received from network and ignores the unknown tail, which makes in tolerant to such schema changes:  https://github.com/apache/cassandra-java-driver/blob/3.x/driver-core/src/main/java/com/datastax/driver/core/TypeCodec.java#L2202
> A code example to illustrate the issue:
> Schema
> {code:java}
> CREATE TYPE test_keyspace.basicInfoInner (
>   weight text,
>   height text
> );
> CREATE TYPE test_keyspace.basicInfo (
>   birthday    timestamp,
>   nationality text,
>   inner       frozen<basicInfoInner>
> );
> CREATE TABLE test_keyspace.tableWithUdt
> (
>     id    varchar,
>     value frozen<list<basicInfo>>,
>     PRIMARY KEY (id)
> ); {code}
> Code:
> {code:java}
> CqlSession session = getSession();
> UdtCodec udtCodec = new UdtCodec(userDefinedType);
> TypeCodec<List<UdtValue>> listOfUdtCodec = TypeCodecs.listOf(udtCodec);
> {
>     ResultSet resultSet = session.execute("select id, value from tableWithUdt");
>     for (Row row : resultSet) {
>         String id = row.getString(0);
>         List<UdtValue> udtValueList = row.get(1, listOfUdtCodec);
>     }
> }
> session.execute("ALTER TYPE basicInfo ADD details text"); 
> session.execute("INSERT INTO tableWithUdt (id, value) VALUES ('4', [\n" +
>         " { birthday : '1993-06-18', " +
>         "   nationality : 'New Zealand', " +
>         "   inner: { weight : '70', height : '70' } " +
>         " },\n" +
>         " { birthday : '1993-06-19', " +
>         "   nationality : null, " +
>         "   inner: { weight : '70', height : null }, " +
>         "   details: 'added details'" + // <=== insert a value for the new added UDT field
>         " }\n" +
>         "  ])");
> {
>     ResultSet resultSet = session.execute("select id, value from tableWithUdt");
>     for (Row row : resultSet) {
>         String id = row.getString(0);
>         //  ==== UdtCodec throws IllegalArgumentException: Too many fields in encoded UDT value, expected 3 ==== 
>         List<UdtValue> udtValueList = row.get(1, listOfUdtCodec);
>     }
> }
> private static UserDefinedType getUserDefinedType(CqlSession session, String udtName) {
>     return session.getMetadata()
>             .getKeyspace(session.getKeyspace().orElseThrow(() -> new IllegalArgumentException("Udt name " + udtName + " can't be loaded due to null keyspace")))
>             .orElseThrow(() -> new IllegalArgumentException("Metadata is not found"))
>             .getUserDefinedType(udtName)
>             .orElseThrow(() -> new IllegalArgumentException("Udt name " + udtName + " isn't found"));
> }
> {code}



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