Status

General

• [x] SQL Parser
• [x] SQL Query Planner
• [x] Query Optimizer
• [x] Constant folding
• [x] Join Reordering
• [x] Limit Pushdown
• [x] Projection push down
• [x] Predicate push down
• [x] Type coercion
• [x] Parallel query execution

SQL Support

• [x] Projection
• [x] Filter (WHERE)
• [x] Filter post-aggregate (HAVING)
• [x] Limit
• [x] Aggregate
• [x] Common math functions
• [x] cast
• [x] try_cast
• [x] VALUES lists
• Postgres compatible String functions
  • [x] ascii
  • [x] bit_length
  • [x] btrim
  • [x] char_length
  • [x] character_length
  • [x] chr
  • [x] concat
  • [x] concat_ws
  • [x] initcap
  • [x] left
  • [x] length
  • [x] lpad
  • [x] ltrim
  • [x] octet_length
  • [x] regexp_replace
  • [x] repeat
  • [x] replace
  • [x] reverse
  • [x] right
  • [x] rpad
  • [x] rtrim
  • [x] split_part
  • [x] starts_with
  • [x] strpos
  • [x] substr
  • [x] to_hex
  • [x] translate
  • [x] trim
• Miscellaneous/Boolean functions
  • [x] nullif
• Approximation functions
  • [x] approx_distinct
• Common date/time functions
  • [ ] Basic date functions
  • [ ] Basic time functions
  • [x] Basic timestamp functions
    • [x] to_timestamp
    • [x] to_timestamp_millis
    • [x] to_timestamp_micros
    • [x] to_timestamp_seconds
• nested functions
  • [x] Array of columns
• [x] Schema Queries
  • [x] SHOW TABLES
  • [x] SHOW COLUMNS
  • [x] information_schema.{tables, columns}
  • [ ] information_schema other views
• [x] Sorting
• [ ] Nested types
• [ ] Lists
• [x] Subqueries
• [x] Common table expressions
• [x] Set Operations
  • [x] UNION ALL
  • [x] UNION
  • [x] INTERSECT
  • [x] INTERSECT ALL
  • [x] EXCEPT
  • [x] EXCEPT ALL
• [x] Joins
  • [x] INNER JOIN
  • [x] LEFT JOIN
  • [x] RIGHT JOIN
  • [x] FULL JOIN
  • [x] CROSS JOIN
• [ ] Window
  • [x] Empty window
  • [x] Common window functions
  • [x] Window with PARTITION BY clause
  • [x] Window with ORDER BY clause
  • [ ] Window with FILTER clause
  • [ ] Window with custom WINDOW FRAME
  • [ ] UDF and UDAF for window functions

Data Sources

• [x] CSV
• [x] Parquet primitive types
• [ ] Parquet nested types

Extensibility

DataFusion is designed to be extensible at all points. To that end, you can provide your own custom:

• [x] User Defined Functions (UDFs)
• [x] User Defined Aggregate Functions (UDAFs)
• [x] User Defined Table Source (TableProvider) for tables
• [x] User Defined Optimizer passes (plan rewrites)
• [x] User Defined LogicalPlan nodes
• [x] User Defined ExecutionPlan nodes

Rust Version Compatbility

This crate is tested with the latest stable version of Rust. We do not currently test against other, older versions of the Rust compiler.

Supported SQL

This library currently supports many SQL constructs, including

• CREATE EXTERNAL TABLE X STORED AS PARQUET LOCATION '...'; to register a table's locations
• SELECT ... FROM ... together with any expression
• ALIAS to name an expression
• CAST to change types, including e.g. Timestamp(Nanosecond, None)
• Many mathematical unary and binary expressions such as +, /, sqrt, tan, >=.
• WHERE to filter
• GROUP BY together with one of the following aggregations: MIN, MAX, COUNT, SUM, AVG, CORR, VAR, COVAR, STDDEV (sample and population)
• ORDER BY together with an expression and optional ASC or DESC and also optional NULLS FIRST or NULLS LAST

Supported Functions

DataFusion strives to implement a subset of the PostgreSQL SQL dialect where possible. We explicitly choose a single dialect to maximize interoperability with other tools and allow reuse of the PostgreSQL documents and tutorials as much as possible.

Currently, only a subset of the PostgreSQL dialect is implemented, and we will document any deviations.

Schema Metadata / Information Schema Support

DataFusion supports the showing metadata about the tables available. This information can be accessed using the views of the ISO SQL information_schema schema or the DataFusion specific SHOW TABLES and SHOW COLUMNS commands.

More information can be found in the Postgres docs).

To show tables available for use in DataFusion, use the SHOW TABLES command or the information_schema.tables view:

> show tables;
+---------------+--------------------+------------+------------+
| table_catalog | table_schema       | table_name | table_type |
+---------------+--------------------+------------+------------+
| datafusion    | public             | t          | BASE TABLE |
| datafusion    | information_schema | tables     | VIEW       |
+---------------+--------------------+------------+------------+

> select * from information_schema.tables;

+---------------+--------------------+------------+--------------+
| table_catalog | table_schema       | table_name | table_type   |
+---------------+--------------------+------------+--------------+
| datafusion    | public             | t          | BASE TABLE   |
| datafusion    | information_schema | TABLES     | SYSTEM TABLE |
+---------------+--------------------+------------+--------------+

To show the schema of a table in DataFusion, use the SHOW COLUMNS command or the or information_schema.columns view:

> show columns from t;
+---------------+--------------+------------+-------------+-----------+-------------+
| table_catalog | table_schema | table_name | column_name | data_type | is_nullable |
+---------------+--------------+------------+-------------+-----------+-------------+
| datafusion    | public       | t          | a           | Int32     | NO          |
| datafusion    | public       | t          | b           | Utf8      | NO          |
| datafusion    | public       | t          | c           | Float32   | NO          |
+---------------+--------------+------------+-------------+-----------+-------------+

>   select table_name, column_name, ordinal_position, is_nullable, data_type from information_schema.columns;
+------------+-------------+------------------+-------------+-----------+
| table_name | column_name | ordinal_position | is_nullable | data_type |
+------------+-------------+------------------+-------------+-----------+
| t          | a           | 0                | NO          | Int32     |
| t          | b           | 1                | NO          | Utf8      |
| t          | c           | 2                | NO          | Float32   |
+------------+-------------+------------------+-------------+-----------+

Supported Data Types

DataFusion uses Arrow, and thus the Arrow type system, for query execution. The SQL types from sqlparser-rs are mapped to Arrow types according to the following table

SQL Data Type	Arrow DataType
CHAR	Utf8
VARCHAR	Utf8
UUID	Not yet supported
CLOB	Not yet supported
BINARY	Not yet supported
VARBINARY	Not yet supported
DECIMAL	Float64
FLOAT	Float32
SMALLINT	Int16
INT	Int32
BIGINT	Int64
REAL	Float32
DOUBLE	Float64
BOOLEAN	Boolean
DATE	Date32
TIME	Time64(TimeUnit::Millisecond)
TIMESTAMP	Timestamp(TimeUnit::Nanosecond)
INTERVAL	Not yet supported
REGCLASS	Not yet supported
TEXT	Not yet supported
BYTEA	Not yet supported
CUSTOM	Not yet supported
ARRAY	Not yet supported