Module datafusion::prelude

A “prelude” for users of the datafusion crate.

Like the standard library’s prelude, this module simplifies importing of common items. Unlike the standard prelude, the contents of this module must be imported manually:

use datafusion::prelude::*;

Re-exports

pub use crate::dataframe::DataFrame;

pub use crate::execution::context::SessionConfig;

pub use crate::execution::context::SessionContext;

pub use crate::execution::options::AvroReadOptions;

pub use crate::execution::options::CsvReadOptions;

pub use crate::execution::options::NdJsonReadOptions;

pub use crate::execution::options::ParquetReadOptions;

Structs

Column

A named reference to a qualified field in a schema.

Enums

Expr

Expr is a central struct of DataFusion’s query API, and represent logical expressions such as A + 1, or CAST(c1 AS int).

JoinType

Join type

Partitioning

Logical partitioning schemes supported by the repartition operator.

Functions

abs

absolute value

acos

inverse cosine

and

Return a new expression with a logical AND

approx_distinct

Returns the approximate number of distinct input values. This function provides an approximation of count(DISTINCT x). Zero is returned if all input values are null. This function should produce a standard error of 0.81%, which is the standard deviation of the (approximately normal) error distribution over all possible sets. It does not guarantee an upper bound on the error for any specific input set.

approx_median

Calculate an approximation of the median for expr.

approx_percentile_cont

Calculate an approximation of the specified percentile for expr.

approx_percentile_cont_with_weight

Calculate an approximation of the specified percentile for expr and weight_expr.

array

Returns an array of fixed size with each argument on it.

arrow_typeof

data type

ascii

Scalar function definition for ascii

asin

inverse sine

atan

inverse tangent

atan2

Scalar function definition for atan2

avg

Create an expression to represent the avg() aggregate function

binary_expr

Return a new expression l r

bit_length

Scalar function definition for bit_length

btrim

Scalar function definition for btrim

call_fn

Calls a named built in function

case

Create a CASE WHEN statement with literal WHEN expressions for comparison to the base expression.

cast

Create a cast expression

ceil

nearest integer greater than or equal to argument

character_length

Scalar function definition for character_length

chr

Scalar function definition for chr

coalesce

Returns coalesce(args...), which evaluates to the value of the first Expr which is not NULL

col

Create a column expression based on a qualified or unqualified column name

combine_filters

Combines an array of filter expressions into a single filter expression consisting of the input filter expressions joined with logical AND. Returns None if the filters array is empty.

combine_filters_disjunctive

Combines an array of filter expressions into a single filter expression consisting of the input filter expressions joined with logical OR. Returns None if the filters array is empty.

concat

Concatenates the text representations of all the arguments. NULL arguments are ignored.

concat_expr

Scalar function definition for concat_expr

concat_ws

Concatenates all but the first argument, with separators. The first argument is used as the separator string, and should not be NULL. Other NULL arguments are ignored.

concat_ws_expr

Scalar function definition for concat_ws_expr

cos

cosine

count

Create an expression to represent the count() aggregate function

count_distinct

Create an expression to represent the count(distinct) aggregate function

create_udaf

Creates a new UDAF with a specific signature, state type and return type. The signature and state type must match the Accumulator's implementation.

create_udf

Creates a new UDF with a specific signature and specific return type. This is a helper function to create a new UDF. The function create_udf returns a subset of all possible ScalarFunction:

cube

Create a grouping set for all combination of exprs

date_bin

Scalar function definition for date_bin

date_part

Scalar function definition for date_part

date_trunc

Scalar function definition for date_trunc

digest

Scalar function definition for digest

exists

Create an EXISTS subquery expression

exp

base 2 logarithm

floor

nearest integer less than or equal to argument

from_unixtime

Scalar function definition for from_unixtime

grouping_set

Create a grouping set

in_list

Create an in_list expression

in_subquery

Create an IN subquery expression

initcap

Scalar function definition for initcap

is_false

Create is false expression

is_not_false

Create is not false expression

is_not_true

Create is not true expression

is_not_unknown

Create is not unknown expression

is_null

Create is null expression

is_true

Create is true expression

is_unknown

Create is unknown expression

left

Scalar function definition for left

length

Scalar function definition for length

lit

Create a literal expression

ln

natural logarithm

log2

base 10 logarithm

log10

base 10 logarithm

lower

Scalar function definition for lower

lpad

Scalar function definition for lpad

ltrim

Scalar function definition for ltrim

max

Create an expression to represent the max() aggregate function

md5

Scalar function definition for md5

min

Create an expression to represent the min() aggregate function

not_exists

Create a NOT EXISTS subquery expression

not_in_subquery

Create a NOT IN subquery expression

now

Returns current timestamp in nanoseconds, using the same value for all instances of now() in same statement.

nullif

Scalar function definition for nullif

octet_length

Scalar function definition for octet_length

or

Return a new expression with a logical OR

power

Scalar function definition for power

random

Returns a random value in the range 0.0 <= x < 1.0

regexp_match

Scalar function definition for regexp_match

regexp_replace

Scalar function definition for regexp_replace

repeat

Scalar function definition for repeat

replace

Scalar function definition for replace

reverse

Scalar function definition for reverse

right

Scalar function definition for right

rollup

Create a grouping set for rollup

round

round to nearest integer

rpad

Scalar function definition for rpad

rtrim

Scalar function definition for rtrim

scalar_subquery

Create a scalar subquery expression

sha224

Scalar function definition for sha224

sha256

Scalar function definition for sha256

sha384

Scalar function definition for sha384

sha512

Scalar function definition for sha512

signum

sign of the argument (-1, 0, +1)

sin

sine

split_part

Scalar function definition for split_part

sqrt

square root of a number

starts_with

Scalar function definition for starts_with

strpos

Scalar function definition for strpos

substr

Scalar function definition for substr

sum

Create an expression to represent the sum() aggregate function

tan

tangent

to_hex

Scalar function definition for to_hex

to_timestamp_micros

Scalar function definition for to_timestamp_micros

to_timestamp_millis

Scalar function definition for to_timestamp_millis

to_timestamp_seconds

Scalar function definition for to_timestamp_seconds

translate

Scalar function definition for translate

trim

Scalar function definition for trim

trunc

truncate toward zero

try_cast

Create a try cast expression

unalias

Recursively un-alias an expressions

uncombine_filter

Take combined filter (multiple boolean expressions ANDed together) and break down into distinct filters. This should be the inverse of combine_filters

upper

Scalar function definition for upper

when

Create a CASE WHEN statement with boolean WHEN expressions and no base expression.