[jira] [Commented] (CASSANDRA-15871) Cassandra driver first connection get the user's own schema information

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

    [ https://issues.apache.org/jira/browse/CASSANDRA-15871?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17135346#comment-17135346 ] 

maxwellguo commented on CASSANDRA-15871:
----------------------------------------

Hi [~brandon.williams],when using a driver to do some operaions on cassandra , different users can get all the schemas information when first made a connection after the Auth setp. 
User A, may store all the keyspaces/tables information in the client side, That's beacuse the client doing query like : "SELECT * FROM System_schema.keyspaces" and get all keyspace from system_schema table。But some keyspace or tables or type may not be created by UserA, It may be UserB;
for my test, I doing some logs at Message.java -> channelRead0(ChannelHandlerContext ctx, Request request)

{code:java}
public void channelRead0(ChannelHandlerContext ctx, Request request)
        {

            final Response response;
            final ServerConnection connection;
            long queryStartNanoTime = System.nanoTime();

            try
            {
                assert request.connection() instanceof ServerConnection;
                connection = (ServerConnection)request.connection();
                if (connection.getVersion().isGreaterOrEqualTo(ProtocolVersion.V4))
                    ClientWarn.instance.captureWarnings();

                QueryState qstate = connection.validateNewMessage(request.type, connection.getVersion(), request.getStreamId());

                logger.info("Received: {}, v={}", request, connection.getVersion()); // here is my logging
                response = request.execute(qstate, queryStartNanoTime);
                logger.info("response : {}", response);// and here is the response.
                response.setStreamId(request.getStreamId());
                response.setWarnings(ClientWarn.instance.getWarnings());
                response.attach(connection);
                connection.applyStateTransition(request.type, response.type);
            }
{code}
for me userA create table : kscas.tbcas ;userB create table ksgc.tbgc
.
But when I using userA to make a connection through cqlsh : my output log shows all tables are return to 
client.
 !1.jpg! 
So I think if it ok that when doing connection through userA, we just return back userA's schema information like table/keyspace/columns/types . 

> Cassandra driver first  connection get the user's own schema information
> ------------------------------------------------------------------------
>
>                 Key: CASSANDRA-15871
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15871
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Cluster/Schema, Messaging/Client
>            Reporter: maxwellguo
>            Priority: Normal
>         Attachments: 1.jpg
>
>
> We know that cassandra driver making a conenction with the coordinator node first time , the driver may select all the keyspaces/tables/columns/types from the server and cache the data locally. 
> For different users they may have different tables and types ，so It is not suitable to get all the meta data cached , It is fine to just cache the user's own schema information not all.
>  And doing this is safe and save first time connection resourse.



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