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From "Jack Krupansky" <j...@basetechnology.com>
Subject Re: Are writes to indexes performed asynchronously?
Date Sun, 22 Jun 2014 15:24:46 GMT
The Cassandra 2.0 doc says that “Indexes are built in the background automatically, without
blocking reads or writes.” IOW, no guarantee that the 2i will have been updated by the time
you attempt a query on it. A GC or just general busyness of the node could delay the 2i update,
even though it may generally complete quicker than you can do a query.

See:
http://www.datastax.com/documentation/cql/3.1/cql/ddl/ddl_build_index_c.html

AFAICT, there is no mechanism for guaranteeing that a 2i has been updated.

-- Jack Krupansky

From: Tom van den Berge 
Sent: Thursday, June 19, 2014 5:26 AM
To: user@cassandra.apache.org 
Subject: Are writes to indexes performed asynchronously?

Hi,

I have a column family with a secondary index on one of its columns. I noticed that when I
write a row to the column family, and immediately query that row through the secondary index,
every now and then it won't give any results.

Could it be that Cassandra performs the write to the internal index column family asynchronously?
That might explain this behaviour. 

In other words, when writing to a indexed column family, is there, or can there be any guarantee
that the write to index is completed when the write to the original column family is completed?

I'm using a single-node cluster, with consistency level ONE.

Thanks,
Tom
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