
# clickhouse-local

The `clickhouse-local` program enables you to perform fast processing on local files, without having to deploy and configure the ClickHouse server.

Accepts data that represent tables and queries them using [ClickHouse SQL dialect](../../query_language/index.md#queries).

`clickhouse-local` uses the same core as ClickHouse server, so it supports most of the features and the same set of formats and table engines.

By default `clickhouse-local` does not have access to data on the same host, but it supports loading server configuration using `--config-file` argument.

!!! warning
    It is not recommended to load production server configuration into `clickhouse-local` because data can be damaged in case of human error.


## Usage

Basic usage:

``` bash
clickhouse-local --structure "table_structure" --input-format "format_of_incoming_data" -q "query"
```

Arguments:

- `-S`, `--structure` — table structure for input data.
- `-if`, `--input-format` — input format, `TSV` by default.
- `-f`, `--file` — path to data, `stdin` by default.
- `-q` `--query` — queries to execute with `;` as delimeter.
- `-N`, `--table` — table name where to put output data, `table` by default.
- `-of`, `--format`, `--output-format` — output format, `TSV` by default.
- `--stacktrace` — whether to dump debug output in case of exception.
- `--verbose` — more details on query execution.
- `-s` — disables `stderr` logging.
- `--config-file` — path to configuration file in same format as for ClickHouse server, by default the configuration empty.
- `--help` — arguments references for `clickhouse-local`.

Also there are arguments for each ClickHouse configuration variable which are more commonly used instead of `--config-file`.


## Examples

``` bash
echo -e "1,2\n3,4" | clickhouse-local -S "a Int64, b Int64" -if "CSV" -q "SELECT * FROM table"
Read 2 rows, 32.00 B in 0.000 sec., 5182 rows/sec., 80.97 KiB/sec.
1	2
3	4
```

Previous example is the same as:

``` bash
$ echo -e "1,2\n3,4" | clickhouse-local -q "CREATE TABLE table (a Int64, b Int64) ENGINE = File(CSV, stdin); SELECT a, b FROM table; DROP TABLE table"
Read 2 rows, 32.00 B in 0.000 sec., 4987 rows/sec., 77.93 KiB/sec.
1	2
3	4
```

Now let's output memory user for each Unix user:

``` bash
$ ps aux | tail -n +2 | awk '{ printf("%s\t%s\n", $1, $4) }' | clickhouse-local -S "user String, mem Float64" -q "SELECT user, round(sum(mem), 2) as memTotal FROM table GROUP BY user ORDER BY memTotal DESC FORMAT Pretty"
Read 186 rows, 4.15 KiB in 0.035 sec., 5302 rows/sec., 118.34 KiB/sec.
┏━━━━━━━━━━┳━━━━━━━━━━┓
┃ user     ┃ memTotal ┃
┡━━━━━━━━━━╇━━━━━━━━━━┩
│ bayonet  │    113.5 │
├──────────┼──────────┤
│ root     │      8.8 │
├──────────┼──────────┤
...
```

[Original article](https://clickhouse.yandex/docs/en/operations/utils/clickhouse-local/) <!--hide-->
