Issue faced while using SimpleDb and Cassandra connector

[pranavk]

Hi,

I noticed that while writing to a VDB using the Cassandra connector (Cassandra based source model contained within a VDB), writes were going very slow. On a single node Cassandra setup inserting a set 50k records and 3 columns took more than 25 mins. Regular writes to cassandra are supposed to very fast. Just wanted to know whether this is an expected/known fact considering the Cassandra apis being called?

I suppose the connector executes the insert queries one by one rather than using batched approach, also the API used is the synchronous one instead of the future based async API [session.executeAsync()]

SimpleDb:

I also noticed that a 'select count(*) from table' query doesnt work with SimpleDb connector. A 'select count(column1)...' works, however.

Following was the error which came up:

TEIID30504 vd-sdb_1-simpledb: Inproper results returned. Expected 1 columns, but was 0

On debugging I noticed that a conditional check for expression type seems to be missing in the method visit(DerivedColumn obj) in the class SimpleDBSQLVisitor, hence projectedColumns list remains empty.

Thanks,

Pranav

[rareddy]

Pranav,

Please create JIRA for the "select count(*)" case.

As far as the write taking long time, I see BatchPutAttributes - Amazon SimpleDB 25 row limit thus may be taking more time. If you can find an alternative then we can see if we can enhance the code

Ramesh..

[pranavk]

Hi Ramesh,

Thanks. I have created a bug [TEIID-3845] for the SimpleDb connector.

As far as the write issue is concerned that I mentioned in the first portion of my post, that was regarding the Cassandra connector and not the SimpleDb connector. Let me know if the issue needs any further clarification.

Thanks,

Pranav

[rareddy]

Pranav,

Looks like the translator did not implement the Bulk Update feature, so you can add enhancement request for it. However, if know any documentation how this is done with Cassandra please add that to the JIRA. BTW, code contributions are welcomed here.

Thanks

Ramesh..