ClickHouse/docs/en/operations/utilities/clickhouse-local.md

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/en/operations/utilities/clickhouse-local	60	clickhouse-local

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.

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. :::

For temporary data, a unique temporary data directory is created by default.

Usage

Basic usage:

$ clickhouse-local --structure "table_structure" --input-format "format_of_incoming_data" \
    --query "query"

Arguments:

• -S, --structure — table structure for input data.
• --input-format — input format, TSV by default.
• -f, --file — path to data, stdin by default.
• -q, --query — queries to execute with ; as delimeter. You must specify either query or queries-file option.
• --queries-file - file path with queries to execute. You must specify either query or queries-file option.
• -N, --table — table name where to put output data, table by default.
• --format, --output-format — output format, TSV by default.
• -d, --database — default database, _local by default.
• --stacktrace — whether to dump debug output in case of exception.
• --echo — print query before execution.
• --verbose — more details on query execution.
• --logger.console — Log to console.
• --logger.log — Log file name.
• --logger.level — Log level.
• --ignore-error — do not stop processing if a query failed.
• -c, --config-file — path to configuration file in same format as for ClickHouse server, by default the configuration empty.
• --no-system-tables — do not attach system tables.
• --help — arguments references for clickhouse-local.
• -V, --version — print version information and exit.

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

Examples

$ echo -e "1,2\n3,4" | clickhouse-local --structure "a Int64, b Int64" \
    --input-format "CSV" --query "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:

$ echo -e "1,2\n3,4" | clickhouse-local --query "
    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

You don't have to use stdin or --file argument, and can open any number of files using the file table function:

$ echo 1 | tee 1.tsv
1

$ echo 2 | tee 2.tsv
2

$ clickhouse-local --query "
    select * from file('1.tsv', TSV, 'a int') t1
    cross join file('2.tsv', TSV, 'b int') t2"
1	2

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

Query:

$ ps aux | tail -n +2 | awk '{ printf("%s\t%s\n", $1, $4) }' \
    | clickhouse-local --structure "user String, mem Float64" \
        --query "SELECT user, round(sum(mem), 2) as memTotal
            FROM table GROUP BY user ORDER BY memTotal DESC FORMAT Pretty"

Result:

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

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