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From Theo Hultberg <t...@iconara.net>
Subject Re: Limit on the size of a list
Date Mon, 13 May 2013 06:51:48 GMT
In the CQL3 protocol the sizes of collections are unsigned shorts, so the
maximum number of elements in a LIST<...> is 65,536. There's no check,
afaik, that stops you from creating lists that are bigger than that, but
the protocol doesn't handle returning them (you get the first N - 65536 %
65536 items).

On the other hand the JDBC driver doesn't talk over the binary protocol but
Thrift, doesn't it? In that case there may be other limits.

T#


On Mon, May 13, 2013 at 3:26 AM, Edward Capriolo <edlinuxguru@gmail.com>wrote:

> 2 billion is the maximum theoretically limit of columns under a row. It is
> NOT the maximum limit of a CQL collection. The design of CQL collections
> currently require retrieving the entire collection on read.
>
>
> On Sun, May 12, 2013 at 11:13 AM, Robert Wille <rwille@footnote.com>wrote:
>
>> I designed a data model for my data that uses a list of UUID's in a
>> column. When I designed my data model, my expectation was that most of the
>> lists would have fewer than a hundred elements, with a few having several
>> thousand. I discovered in my data a list that has nearly 400,000 items in
>> it. When I try to retrieve it, I get the following exception:
>>
>> java.lang.IllegalArgumentException: Illegal Capacity: -14594
>>         at java.util.ArrayList.<init>(ArrayList.java:110)
>>         at
>> org.apache.cassandra.cql.jdbc.ListMaker.compose(ListMaker.java:54)
>>         at
>> org.apache.cassandra.cql.jdbc.TypedColumn.<init>(TypedColumn.java:68)
>>         at
>>
>> org.apache.cassandra.cql.jdbc.CassandraResultSet.createColumn(CassandraResu
>> ltSet.java:1086)
>>         at
>>
>> org.apache.cassandra.cql.jdbc.CassandraResultSet.populateColumns(CassandraR
>> esultSet.java:161)
>>         at
>>
>> org.apache.cassandra.cql.jdbc.CassandraResultSet.<init>(CassandraResultSet.
>> java:134)
>>         at
>>
>> org.apache.cassandra.cql.jdbc.CassandraStatement.doExecute(CassandraStateme
>> nt.java:166)
>>         at
>>
>> org.apache.cassandra.cql.jdbc.CassandraStatement.executeQuery(CassandraStat
>> ement.java:226)
>>
>>
>> I get this with Cassandra 1.2.4 and the latest snapshot of the JDBC
>> driver. Admittedly, several hundred thousand is quite a lot of items, but
>> odd that I'm getting some kind of wraparound, since 400,000 is a long ways
>> from 2 billion.
>>
>> What are the physical and practical limits on the size of a list? Is it
>> possible to retrieve a range of items from a list?
>>
>> Thanks in advance
>>
>> Robert
>>
>>
>>
>

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