Crate datafusion_functions_aggregate

Expand description

Aggregate Function packages for DataFusion.

This crate contains a collection of various aggregate function packages for DataFusion, implemented using the extension API. Users may wish to control which functions are available to control the binary size of their application as well as use dialect specific implementations of functions (e.g. Spark vs Postgres)

Each package is implemented as a separate module, activated by a feature flag.

§Available Packages

See the list of modules in this crate for available packages.

§Using A Package

You can register all functions in all packages using the register_all function.

Each package also exports an expr_fn submodule to help create Exprs that invoke functions using a fluent style. For example:

§Implementing A New Package

To add a new package to this crate, you should follow the model of existing packages. The high level steps are:

Create a new module with the appropriate AggregateUDF implementations.
Use the macros in macros to create standard entry points.
Add a new feature to Cargo.toml, with any optional dependencies
Use the make_package! macro to expose the module when the feature is enabled.

Modules§

approx_distinct: Defines physical expressions that can evaluated at runtime during query execution
approx_median: Defines physical expressions for APPROX_MEDIAN that can be evaluated MEDIAN at runtime during query execution
approx_percentile_cont
approx_percentile_cont_with_weight
array_agg: ARRAY_AGG aggregate implementation: ArrayAgg
average: Defines Avg & Mean aggregate & accumulators
bit_and_or_xor: Defines BitAnd, BitOr, BitXor and BitXor DISTINCT aggregate accumulators
bool_and_or: Defines physical expressions that can evaluated at runtime during query execution
correlation: Correlation: correlation sample aggregations.
count
covariance: CovarianceSample: covariance sample aggregations.
expr_fn: Fluent-style API for creating Exprs
first_last: Defines the FIRST_VALUE/LAST_VALUE aggregations.
grouping: Defines physical expressions that can evaluated at runtime during query execution
hyperloglog: HyperLogLog
macros
median
min_max: Max and MaxAccumulator accumulator for the max function Min and MinAccumulator accumulator for the min function
nth_value: Defines NTH_VALUE aggregate expression which may specify ordering requirement that can evaluated at runtime during query execution
regr: Defines physical expressions that can evaluated at runtime during query execution
stddev: Defines physical expressions that can evaluated at runtime during query execution
string_agg: StringAgg accumulator for the string_agg function
sum: Defines SUM and SUM DISTINCT aggregate accumulators
variance: VarianceSample: variance sample aggregations. VariancePopulation: variance population aggregations.

Functions§

all_default_aggregate_functions: Returns all default aggregate functions
register_all: Registers all enabled packages with a FunctionRegistry