[CASSANDRA-10328] Inconsistent Schema Change Events Between Table and View

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Duplicate
• Component/s: Feature/Materialized Views, Legacy/Tools
• Severity: Normal
• Assignee: Stefania Alborghetti
• Reporter: Adam Holmberg

Authors

Stefania Alborghetti

• Created: 14/Sep/15 19:52
• Updated: 16/Apr/19 09:30
• Resolved: 17/Sep/15 02:42

Description

I'm seeing inconsistent event delivery when it comes to dropping materialized views (when compared to tables or indexes).

For example, create/drop/alter for a table:

cassandra@cqlsh:test> create TABLE t (k int PRIMARY KEY , v int);
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'CREATED', 'target_type': u'TABLE', u'table': u't'}, stream_id=-1)>
cassandra@cqlsh:test> alter TABLE t add v1 int;
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'TABLE', u'table': u't'}, stream_id=-1)>
cassandra@cqlsh:test> drop TABLE t;
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'DROPPED', 'target_type': u'TABLE', u'table': u't'}, stream_id=-1)>

And for a view:

cassandra@cqlsh:test> create MATERIALIZED VIEW mv as select * from scores WHERE game IS NOT NULL AND score IS NOT NULL AND user IS NOT NULL AND year IS NOT NULL AND month IS NOT NULL AND day IS NOT NULL        PRIMARY KEY (game, user, year, month, day, score)        WITH CLUSTERING ORDER BY (score desc);
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'CREATED', 'target_type': u'TABLE', u'table': u'mv'}, stream_id=-1)>
cassandra@cqlsh:test> alter materialized view mv with min_index_interval = 100;
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'TABLE', u'table': u'mv'}, stream_id=-1)>
cassandra@cqlsh:test> drop MATERIALIZED VIEW mv;
<EventMessage(event_type=u'SCHEMA_CHANGE', trace_id=None, event_args={'keyspace': u'test', 'change_type': u'UPDATED', 'target_type': u'KEYSPACE'}, stream_id=-1)>

The latter sequence is missing a table update event, meaning clients cannot tell that a view was dropped.
This is on a branch in-progress for CASSANDRA-9921

As a side note, I also believe they keyspace update events are unnecessary in both scenarios. To my knowledge, drivers only use these events to refresh meta on the keyspace definition itself, not the entities it contains. Please let me know if this is worthy of discussion or a distinct ticket.

Issue Links

• is duplicated by: CASSANDRA-9961 cqlsh should have DESCRIBE MATERIALIZED VIEW
• relates to: CASSANDRA-9921 Combine MV schema definition with MV table definition