docs/source/user-guide/features.md

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# Features

## General

- [x] SQL Parser
- [x] SQL Query Planner
- [x] DataFrame API
- [x] Parallel query execution
- [x] Streaming Execution

## Optimizations

- [x] Query Optimizer
- [x] Constant folding
- [x] Join Reordering
- [x] Limit Pushdown
- [x] Projection push down
- [x] Predicate push down

## SQL Support

- [x] Type coercion
- [x] Projection (`SELECT`)
- [x] Filter (`WHERE`)
- [x] Filter post-aggregate (`HAVING`)
- [x] Sorting (`ORDER BY`)
- [x] Limit (`LIMIT`)
- [x] Aggregate (`GROUP BY`)
- [x] cast /try_cast
- [x] [`VALUES` lists](https://www.postgresql.org/docs/current/queries-values.html)
- [x] [String Functions](./sql/scalar_functions.md#string-functions)
- [x] [Conditional Functions](./sql/scalar_functions.md#conditional-functions)
- [x] [Time and Date Functions](./sql/scalar_functions.md#time-and-date-functions)
- [x] [Math Functions](./sql/scalar_functions.md#math-functions)
- [x] [Aggregate Functions](./sql/aggregate_functions.md) (`SUM`, `MEDIAN`, and many more)
- [x] Schema Queries
  - [x] `SHOW TABLES`
  - [x] `SHOW COLUMNS FROM <table/view>`
  - [x] `SHOW CREATE TABLE <view>`
  - [x] Basic SQL [Information Schema](./sql/information_schema.md) (`TABLES`, `VIEWS`, `COLUMNS`)
  - [ ] Full SQL [Information Schema](./sql/information_schema.md) support
- [x] Support for nested types (`ARRAY`/`LIST` and `STRUCT`.
  - [x] Read support
  - [x] Write support
  - [x] Field access (`col['field']` and [`col[1]`])
  - [x] [Array Functions](./sql/scalar_functions.md#array-functions)
  - [x] [Struct Functions](./sql/scalar_functions.md#struct-functions)
    - [x] `struct`
    - [ ] [Postgres JSON operators](https://github.com/apache/datafusion/issues/6631) (`->`, `->>`, etc.)
- [x] Subqueries
- [x] Common Table Expressions (CTE)
- [x] Set Operations (`UNION [ALL]`, `INTERSECT [ALL]`, `EXCEPT[ALL]`)
- [x] Joins (`INNER`, `LEFT`, `RIGHT`, `FULL`, `CROSS`)
- [x] Window Functions
  - [x] Empty (`OVER()`)
  - [x] Partitioning and ordering: (`OVER(PARTITION BY <..> ORDER BY <..>)`)
  - [x] Custom Window (`ORDER BY time ROWS BETWEEN 2 PRECEDING AND 0 FOLLOWING)`)
  - [x] User Defined Window and Aggregate Functions
- [x] Catalogs
  - [x] Schemas (`CREATE / DROP SCHEMA`)
  - [x] Tables (`CREATE / DROP TABLE`, `CREATE TABLE AS SELECT`)
- [x] Data Insert
  - [x] `INSERT INTO`
  - [x] `COPY .. INTO ..`
  - [x] CSV
  - [x] JSON
  - [x] Parquet
  - [ ] Avro

## Runtime

- [x] Streaming Grouping
- [x] Streaming Window Evaluation
- [x] Memory limits enforced
- [x] Spilling (to disk) Sort
- [x] Spilling (to disk) Grouping
- [x] Spilling (to disk) Sort Merge Join
- [ ] Spilling (to disk) Hash Join

## Data Sources

In addition to allowing arbitrary datasources via the [`TableProvider`]
trait, DataFusion includes built in support for the following formats:

- [x] CSV
- [x] Parquet
  - [x] Primitive and Nested Types
  - [x] Row Group and Data Page pruning on min/max statistics
  - [x] Row Group pruning on Bloom Filters
  - [x] Predicate push down (late materialization) [not by default](https://github.com/apache/datafusion/issues/3463)
- [x] JSON
- [x] Avro
- [x] Arrow

[`tableprovider`]: https://docs.rs/datafusion/latest/datafusion/catalog/trait.TableProvider.html