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https://issues.apache.org/jira/browse/CASSANDRA-9550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14573612#comment-14573612
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Brian Hess commented on CASSANDRA-9550:
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There is a difference between arbitrary precision numbers (namely BigDecimal)
and fixed precision numbers (namely SQL's NUMERIC). Are you suggesting that we
use DECIMAL in C* instead of NUMERIC(p,s) in SQL systems?
The fixed precision is frequently needed in SQL - especially in financial
situations (which we specifically call out in the C* docs). Scaling by a
factor in the app does not work well with the advent of UDFs and UDAs. For
example, the scale changes on multiplication and division, and without
NUMERIC(p,s) you would not be able to convey that the scale changed.
> Support fixed precision data type
> ---------------------------------
>
> Key: CASSANDRA-9550
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9550
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Brian Hess
>
> SQL databases support a fixed precision data type. When converting data
> models from SQL DBs to Cassandra, the choices are not clear. DOUBLE or FLOAT
> are possibilities, but with UDFs and Aggregates this is actually a lot less
> clear, as you really do need fixed precision arithmetic. That is, one flaw
> with floating-point math is that the order of the operations can change the
> final result. That is not an issue with fixed precision arithmetic (though
> other trade-offs are there).
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