Module datafusion::common

re-export of datafusion_common crate

Modules

• alias
• cast
  This module provides DataFusion specific casting functions that provide error handling. They are intended to “never fail” but provide an error message rather than a panic, as the corresponding kernels in arrow-rs such as as_boolean_array do.
• config
  Runtime configuration, via ConfigOptions
• display
  Types for plan display
• file_options
  Options related to how files should be written
• format
• parsers
  Interval parsing logic
• scalar
  This module provides ScalarValue, an enum that can be used for storage of single elements
• stats
  This module provides data structures to represent statistics
• test_util
  Utility functions to make testing DataFusion based crates easier
• tree_node
  This module provides common traits for visiting or rewriting tree data structures easily.
• utils
  This module provides the bisect function, which implements binary search.

Macros

• assert_contains
  A macro to assert that one string is contained within another with a nice error message if they are not.
• assert_not_contains
  A macro to assert that one string is NOT contained within another with a nice error message if they are are.
• context
• downcast_value
  Downcast an Arrow Array to a concrete type, return an DataFusionError::Internal if the cast is not possible. In normal usage of DataFusion the downcast should always succeed.
• exec_err
• extensions_options
  Convenience macro to create ExtensionsOptions.
• internal_err
• not_impl_err
• plan_err
• sql_err
• unwrap_or_internal_err
  Unwrap an Option if possible. Otherwise return an DataFusionError::Internal. In normal usage of DataFusion the unwrap should always succeed.

Structs

• Column
  A named reference to a qualified field in a schema.
• ColumnStatistics
  Statistics for a column within a relation
• Constraints
  This object encapsulates a list of functional constraints:
• DFField
  DFField wraps an Arrow field and adds an optional qualifier
• DFSchema
  DFSchema wraps an Arrow schema and adds relation names
• FileCompressionType
  Readable file compression type
• FunctionalDependence
  This object defines a functional dependence in the schema. A functional dependence defines a relationship between determinant keys and dependent columns. A determinant key is a column, or a set of columns, whose value uniquely determines values of some other (dependent) columns. If two rows have the same determinant key, dependent columns in these rows are necessarily the same. If the determinant key is unique, the set of dependent columns is equal to the entire schema and the determinant key can serve as a primary key. Note that a primary key may “downgrade” into a determinant key due to an operation such as a join, and this object is used to track dependence relationships in such cases. For more information on functional dependencies, see: https://www.scaler.com/topics/dbms/functional-dependency-in-dbms/
• FunctionalDependencies
  This object encapsulates all functional dependencies in a given relation.
• ResolvedTableReference
  A resolved path to a table of the form “catalog.schema.table”
• Statistics
  Statistics for a relation Fields are optional and can be inexact because the sources sometimes provide approximate estimates for performance reasons and the transformations output are not always predictable.
• UnnestOptions
  Options for unnesting a column that contains a list type, replicating values in the other, non nested rows.

Enums

• DataFusionError
  DataFusion error
• Dependency
  Describes functional dependency mode.
• FileType
  Readable file type
• FileTypeWriterOptions
  This type contains all options needed to initialize a particular RecordBatchWriter type. Each element in the enum contains a thin wrapper around a “writer builder” type (e.g. arrow::csv::WriterBuilder) plus any DataFusion specific writing options (e.g. CSV compression)
• JoinConstraint
  Join constraint
• JoinType
  Join type
• ScalarValue
  Represents a dynamically typed, nullable single value. This is the single-valued counter-part to arrow’s Array.
• SchemaError
  Schema-related errors
• SchemaReference
• TableReference
  TableReferences represent a multi part identifier (path) to a table that may require further resolution.

Constants

• DEFAULT_ARROW_EXTENSION
  The default file extension of arrow files
• DEFAULT_AVRO_EXTENSION
  The default file extension of avro files
• DEFAULT_CSV_EXTENSION
  The default file extension of csv files
• DEFAULT_JSON_EXTENSION
  The default file extension of json files
• DEFAULT_PARQUET_EXTENSION
  The default file extension of parquet files

Traits

• ExprSchema
  Provides schema information needed by certain methods of Expr (defined in the datafusion-common crate).
• GetExt
  Define each FileType/FileCompressionType’s extension
• ScalarType
  Trait used to map a NativeType to a ScalarValue
• SchemaExt
  DataFusion-specific extensions to Schema.
• ToDFSchema
  Convenience trait to convert Schema like things to DFSchema and DFSchemaRef with fewer keystrokes

Functions

• aggregate_functional_dependencies
  Calculates functional dependencies for aggregate output, when there is a GROUP BY expression.
• field_not_found
  Create a “field not found” DataFusion::SchemaError
• get_target_functional_dependencies
  Returns target indices, for the determinant keys that are inside group by expressions.
• project_schema
  Applies an optional projection to a SchemaRef, returning the projected schema
• unqualified_field_not_found
  Convenience wrapper over field_not_found for when there is no qualifier

Type Aliases

• DFSchemaRef
  A reference-counted reference to a DFSchema.
• OwnedSchemaReference
• OwnedTableReference
  This is a TableReference that has ’static lifetime (aka it owns the underlying string)
• Result
  Result type for operations that could result in an DataFusionError
• SharedResult
  Result type for operations that could result in an DataFusionError and needs to be shared (wrapped into Arc).