incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Mark Robson <mar...@gmail.com>
Subject Re: How to generate 'unique' identifiers for use in Cassandra
Date Tue, 27 Apr 2010 22:17:18 GMT
>
> 2010/4/26 Roland Hänel <roland@haenel.me>:
> > Typically, in the SQL world we use things like AUTO_INCREMENT columns
> that
> > let us create a unique key automatically if a row is inserted into a
> table.
>

auto_increment is an antipattern; it adds an extra key which you don't need
(usually). If your data has a natural candidate key, use that. If not, add
extra parts until you have a unique key.

If you are using OrderPreservingParitioner, it is really important to use
keys which can give you a lexically sortable range to scan when you need to
find them, so that you can use get_range_slice etc.

There are other approaches however - in some cases it may be possible to use
columns instead of rows there. But you'd still need keys for the columns.

A straightforward way of generating unique IDs for your objects is to add an
incrementing ID (managed locally) to the host name of the (client) node
where they were generated. But this is probably not helpful in most cases.

Mark

Mime
View raw message