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Merge pull request #8430 from BayoNet/en-docs/CLICKHOUSEDOCS-395-ORC-format

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DOCS-395: ORC format support
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docs/en/interfaces/formats.md
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@ -29,6 +29,7 @@ The supported formats are:
| [PrettySpace](#prettyspace) | ✗ | ✔ | | [PrettySpace](#prettyspace) | ✗ | ✔ |
| [Protobuf](#protobuf) | ✔ | ✔ | | [Protobuf](#protobuf) | ✔ | ✔ |
| [Parquet](#data-format-parquet) | ✔ | ✔ | | [Parquet](#data-format-parquet) | ✔ | ✔ |
| [ORC](#data-format-orc) | ✔ | ✗ |
| [RowBinary](#rowbinary) | ✔ | ✔ | | [RowBinary](#rowbinary) | ✔ | ✔ |
| [RowBinaryWithNamesAndTypes](#rowbinarywithnamesandtypes) | ✔ | ✔ | | [RowBinaryWithNamesAndTypes](#rowbinarywithnamesandtypes) | ✔ | ✔ |
| [Native](#native) | ✔ | ✔ | | [Native](#native) | ✔ | ✔ |
@ -954,16 +955,57 @@ Data types of a ClickHouse table columns can differ from the corresponding field
You can insert Parquet data from a file into ClickHouse table by the following command: You can insert Parquet data from a file into ClickHouse table by the following command:
```bash ```bash
cat {filename} | clickhouse-client --query="INSERT INTO {some_table} FORMAT Parquet" $ cat {filename} | clickhouse-client --query="INSERT INTO {some_table} FORMAT Parquet"
``` ```
You can select data from a ClickHouse table and save them into some file in the Parquet format by the following command: You can select data from a ClickHouse table and save them into some file in the Parquet format by the following command:
```sql ```bash
clickhouse-client --query="SELECT * FROM {some_table} FORMAT Parquet" > {some_file.pq} $ clickhouse-client --query="SELECT * FROM {some_table} FORMAT Parquet" > {some_file.pq}
``` ```
To exchange data with the Hadoop, you can use [HDFS table engine](../operations/table_engines/hdfs.md). To exchange data with Hadoop, you can use [HDFS table engine](../operations/table_engines/hdfs.md).
## ORC {#data-format-orc}
[Apache ORC](https://orc.apache.org/) is a columnar storage format widespread in the Hadoop ecosystem. ClickHouse supports only read operations for this format.
### Data Types Matching
The table below shows supported data types and how they match ClickHouse [data types](../data_types/index.md) in `INSERT` queries.
| ORC data type (`INSERT`) | ClickHouse data type |
| -------------------- | ------------------ |
| `UINT8`, `BOOL` | [UInt8](../data_types/int_uint.md) |
| `INT8` | [Int8](../data_types/int_uint.md) |
| `UINT16` | [UInt16](../data_types/int_uint.md) |
| `INT16` | [Int16](../data_types/int_uint.md) |
| `UINT32` | [UInt32](../data_types/int_uint.md) |
| `INT32` | [Int32](../data_types/int_uint.md) |
| `UINT64` | [UInt64](../data_types/int_uint.md) |
| `INT64` | [Int64](../data_types/int_uint.md) |
| `FLOAT`, `HALF_FLOAT` | [Float32](../data_types/float.md) |
| `DOUBLE` | [Float64](../data_types/float.md) |
| `DATE32` | [Date](../data_types/date.md) |
| `DATE64`, `TIMESTAMP` | [DateTime](../data_types/datetime.md) |
| `STRING`, `BINARY` | [String](../data_types/string.md) |
| `DECIMAL` | [Decimal](../data_types/decimal.md) |
ClickHouse supports configurable precision of `Decimal` type. The `INSERT` query treats the ORC `DECIMAL` type as the ClickHouse `Decimal128` type.
Unsupported ORC data types: `DATE32`, `TIME32`, `FIXED_SIZE_BINARY`, `JSON`, `UUID`, `ENUM`.
Data types of a ClickHouse table columns can differ from the corresponding fields of the ORC data inserted. When inserting data, ClickHouse interprets data types according to the table above and then [cast](../query_language/functions/type_conversion_functions/#type_conversion_function-cast) the data to that data type which is set for the ClickHouse table column.
### Inserting Data
You can insert Parquet data from a file into ClickHouse table by the following command:
```bash
$ cat {filename} | clickhouse-client --query="INSERT INTO {some_table} FORMAT ORC"
```
To exchange data with Hadoop, you can use [HDFS table engine](../operations/table_engines/hdfs.md).
## Format Schema {#formatschema} ## Format Schema {#formatschema}