--- title: Arrow Flight and Deephaven sidebar_label: Arrow Flight --- [Apache Arrow](https://arrow.apache.org/) is a high-performance language-independent columnar memory format for flat and nested data. Deephaven's Arrow Flight integration enables users to import and export data via native remote Flight clients over gRPC. ## Unsupported Types / Features - Maps have very limited support as Deephaven Column Sources cannot keep track of key or value types. - No support for large types such as LargeUtf8, LargeBinary, LargeList, and LargeListView (requires simulating 64-bit arrays). - No support for structs. - No support for run-end encoding. - No support for dictionary encoding. - No support for Utf8View or BinaryView. ## Arrow Type Support Matrix Deephaven supports a wide range of Arrow types. The following table summarizes the supported Arrow types and their corresponding Deephaven types. The table also includes notes on coercions and other relevant information. | Arrow Type | Default Deephaven Type | Supported Coercions | Notes | | ------------------------------------- | ------------------------------------------------------------------------------- | ------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `Bool` | `Boolean` | `byte`, `boolean` | Primitive `boolean` is typically automatically boxed to allow for nulls, but may be targeted for array types. | | `Int(8, signed)` | `byte` | `char`, `short`, `int`, `long`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(8, unsigned)` | `short` | `byte`, `char`, `int`, `long`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(16, signed)` | `short` | `byte`, `char`, `int`, `long`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(16, unsigned)` | `char` | `byte`, `short`, `int`, `long`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(32, signed)` | `int` | `byte`, `char`, `short`, `long`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(32, unsigned)` | `long` | `byte`, `char`, `short`, `int`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(64, signed)` | `long` | `byte`, `char`, `short`, `int`, `float`, `double`, `BigInteger`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Int(64, unsigned)` | `BigInteger` | `byte`, `char`, `short`, `int`, `long`, `float`, `double`, `BigDecimal` | See notes on [integral coercion](#integral-coercion). | | `Decimal` | `BigDecimal` | `byte`, `char`, `short`, `int`, `long`, `float`, `double`, `BigInteger` | See notes on [decimal coercion](#decimal-coercion). | | `FloatingPoint(precision)` | `float` (for HALF/SINGLE) or `double` (for DOUBLE) | `byte`, `char`, `short`, `int`, `long`, `BigDecimal`, `BigInteger` | See notes on [decimal coercion](#decimal-coercion). | | `Time(timeUnit, bitWidth)` | `LocalTime` | — | Time-of-day values; bit width (32 or 64) depends on the time unit. | | `Timestamp(timeUnit, [timeZone])` | `Instant` (or `ZonedDateTime` if non-UTC timezone provided) | `long`, `LocalDateTime` | It is assumed that the unit of a `long` column, being treated as a `Timestamp`, is in nanoseconds. On the wire, this value is adjusted to match the field's TimeUnit. | | `Date(dateUnit)` | `LocalDate` | — | | | `Duration(timeUnit)` | `Duration` | — | | | `Interval(intervalUnit)` | `Period` (YEAR_MONTH), `Duration` (DAY_TIME), `PeriodDuration` (MONTH_DAY_NANO) | May allow limited cross‑coercion between interval types. | Deephaven's implementation matches the Arrow-Java implementation, using Flight's `PeriodDuration`, for this column type. | | `Utf8` | `String` | — | Text encoded as UTF‑8. | | `Binary` | `byte[]` | `ByteVector`, `ByteBuffer` | [Custom mappings](#further-customization) are supported. Deephaven has custom encodings for BigDecimal, BigInteger, and Arrow Flight's Schema POJO. | | `FixedSizeBinary(fixedLength)` | `byte[]` | `ByteVector, ByteBuffer` | [Custom mappings](#further-customization) are supported. | | `SparseUnion`/`DenseUnion` | `Object` | — | Union types (dense or sparse) map to a generic `Object` column type. | | `Null` | `Object` | — | Best when coupled with a Union or when [specifying the Deephaven type to use](#further-customization). | | `Map` | `LinkedHashMap` | — | Map types require that the [Arrow schema is specified](#further-customization). Cells are accumulated into `LinkedHashMap`s; it's not possible to pick another collector at this time. | | `List` / `ListView` / `FixedSizeList` | `T[]` - a native Java array of the inner field | Supports conversion to Deephaven internal `Vector` types such as `LongVector`. | Note that the `deephaven:componentType` metadata key must be set to the inner type. Fixed-size list wire formats will be truncated and/or null-padded to match the data as best as possible. | ### Integral Coercion Integral coercion from a larger type to a smaller type follows typical truncation rules, however, some values will be "truncated" to `null` values. For example `0x2080` will be truncated to `null` when coerced to a `byte` value as `QueryConstants.NULL_BYTE` is `0x80`. Similarly, any `-1` will be coerced to `null` when coerced to a `char` as `QueryConstants.NULL_CHAR` is `0xFFFF`. ### Decimal Coercion Decimal coercion from a type with higher precision to a type with lower precision may result in rounding or truncation. For example, coercion to any integral type will lose the fractional part of the decimal value. ## Further customization Please see the [Groovy documentation](/core/groovy/docs/how-to-guides/data-import-export/arrow-flight) for more details and examples. ## Related documentation - [Barrage Extensions Package Summary](https://docs.deephaven.io/core/javadoc/io/deephaven/extensions/barrage/package-summary.html) - [Arrow Flight Package Summary](https://docs.deephaven.io/core/javadoc/org/apache/arrow/flight/package-summary.html)