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101 lines
4.7 KiB
Markdown
101 lines
4.7 KiB
Markdown
---
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slug: /en/interfaces/grpc
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sidebar_position: 19
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sidebar_label: gRPC Interface
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---
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# gRPC Interface
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## Introduction {#grpc-interface-introduction}
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ClickHouse supports [gRPC](https://grpc.io/) interface. It is an open source remote procedure call system that uses HTTP/2 and [Protocol Buffers](https://en.wikipedia.org/wiki/Protocol_Buffers). The implementation of gRPC in ClickHouse supports:
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- SSL;
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- authentication;
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- sessions;
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- compression;
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- parallel queries through the same channel;
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- cancellation of queries;
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- getting progress and logs;
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- external tables.
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The specification of the interface is described in [clickhouse_grpc.proto](https://github.com/ClickHouse/ClickHouse/blob/master/src/Server/grpc_protos/clickhouse_grpc.proto).
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## gRPC Configuration {#grpc-interface-configuration}
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To use the gRPC interface set `grpc_port` in the main [server configuration](../operations/configuration-files.md). Other configuration options see in the following example:
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```xml
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<grpc_port>9100</grpc_port>
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<grpc>
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<enable_ssl>false</enable_ssl>
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<!-- The following two files are used only if SSL is enabled -->
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<ssl_cert_file>/path/to/ssl_cert_file</ssl_cert_file>
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<ssl_key_file>/path/to/ssl_key_file</ssl_key_file>
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<!-- Whether server requests client for a certificate -->
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<ssl_require_client_auth>false</ssl_require_client_auth>
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<!-- The following file is used only if ssl_require_client_auth=true -->
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<ssl_ca_cert_file>/path/to/ssl_ca_cert_file</ssl_ca_cert_file>
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<!-- Default compression algorithm (applied if client doesn't specify another algorithm, see result_compression in QueryInfo).
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Supported algorithms: none, deflate, gzip, stream_gzip -->
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<compression>deflate</compression>
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<!-- Default compression level (applied if client doesn't specify another level, see result_compression in QueryInfo).
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Supported levels: none, low, medium, high -->
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<compression_level>medium</compression_level>
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<!-- Send/receive message size limits in bytes. -1 means unlimited -->
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<max_send_message_size>-1</max_send_message_size>
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<max_receive_message_size>-1</max_receive_message_size>
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<!-- Enable if you want to get detailed logs -->
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<verbose_logs>false</verbose_logs>
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</grpc>
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```
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## Built-in Client {#grpc-client}
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You can write a client in any of the programming languages supported by gRPC using the provided [specification](https://github.com/ClickHouse/ClickHouse/blob/master/src/Server/grpc_protos/clickhouse_grpc.proto).
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Or you can use a built-in Python client. It is placed in [utils/grpc-client/clickhouse-grpc-client.py](https://github.com/ClickHouse/ClickHouse/blob/master/utils/grpc-client/clickhouse-grpc-client.py) in the repository. The built-in client requires [grpcio and grpcio-tools](https://grpc.io/docs/languages/python/quickstart) Python modules.
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The client supports the following arguments:
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- `--help` – Shows a help message and exits.
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- `--host HOST, -h HOST` – A server name. Default value: `localhost`. You can use IPv4 or IPv6 addresses also.
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- `--port PORT` – A port to connect to. This port should be enabled in the ClickHouse server configuration (see `grpc_port`). Default value: `9100`.
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- `--user USER_NAME, -u USER_NAME` – A user name. Default value: `default`.
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- `--password PASSWORD` – A password. Default value: empty string.
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- `--query QUERY, -q QUERY` – A query to process when using non-interactive mode.
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- `--database DATABASE, -d DATABASE` – A default database. If not specified, the current database set in the server settings is used (`default` by default).
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- `--format OUTPUT_FORMAT, -f OUTPUT_FORMAT` – A result output [format](formats.md). Default value for interactive mode: `PrettyCompact`.
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- `--debug` – Enables showing debug information.
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To run the client in an interactive mode call it without `--query` argument.
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In a batch mode query data can be passed via `stdin`.
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**Client Usage Example**
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In the following example a table is created and loaded with data from a CSV file. Then the content of the table is queried.
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``` bash
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./clickhouse-grpc-client.py -q "CREATE TABLE grpc_example_table (id UInt32, text String) ENGINE = MergeTree() ORDER BY id;"
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echo "0,Input data for" > a.txt ; echo "1,gRPC protocol example" >> a.txt
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cat a.txt | ./clickhouse-grpc-client.py -q "INSERT INTO grpc_example_table FORMAT CSV"
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./clickhouse-grpc-client.py --format PrettyCompact -q "SELECT * FROM grpc_example_table;"
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```
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Result:
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``` text
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┌─id─┬─text──────────────────┐
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│ 0 │ Input data for │
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│ 1 │ gRPC protocol example │
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└────┴───────────────────────┘
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```
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