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The Decimal datatype in Hive based on Java's BigDecimal which is used for representing immutable arbitrary precision decimal numbers in Java. All regular number operations (e.g. +, -, *, /) and relevant UDFs (e.g. Floor, Ceil, Round, and many more) have been updated to handle decimal types. You can cast to/from decimal types like you would do with other numeric types. The persistence format of decimal type supports both scientific and non-scientific notation. Therefore, regardless of whether your dataset contains data like 1E+44 (scientific notation) or 4004 (non-scientific notation) or a combination of both, decimal datatype can be used for it.

With the present implementation, the Decimal datatype has unlimited precision. While this has absolutely no impact on usability, it's worth noting for performance reasons. HIVE-3796 is tracking the progress of allowing users to specify scale and precision when creating tables with decimal datatype.

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