databend-local
databend-local is a simplified version of Databend for easy SQL interaction and testing directly from the command line, without the need for a full Databend deployment. It's perfect for developers and testers looking for a lightweight, hassle-free way to explore Databend features.
databend-local runs a temporary databend-query process. Data storage is in a temporary directory, and all resources, including data, are deleted when the process ends. Be cautious to prevent unintended data loss.
Setting up databend-local
Download the installation package suitable for your platform from the Download page, and extract the databend-query binary located in the bin folder from the installation package.
Add the path to the databend-query binary to your PATH environment variable. For example, if your databend-query binary is located in the folder /Users/eric/Downloads/data, set the PATH environment variable as follows:
macdeMacBook-Pro:rsdoc eric$ export PATH=/Users/eric/Downloads/data:$PATH
- Create an alias called "databend-local" for the "databend-query local" command:
macdeMacBook-Pro:rsdoc eric$ alias databend-local="databend-query local"
- Run databend-local:
macdeMacBook-Pro:rsdoc eric$ databend-local
Welcome to Databend, version v1.2.100-nightly-29d6bf3217(rust-1.72.0-nightly-2023-09-05T16:14:14.152454000Z).
databend-local:)
To exit databend-local, simple type "exit":
databend-local:) exit
Bye~
macdeMacBook-Pro:rsdoc eric$
To view available arguments for databend-local:
macdeMacBook-Pro:rsdoc eric$ databend-local --help
Usage: databend-query local [OPTIONS]
Options:
-q, --query <QUERY> [default: ]
--output-format <OUTPUT_FORMAT> [default: ]
-h, --help Print help
| Argument | Description |
|---|---|
| -q, --query | Specifies the query to be executed. |
| --output-format | Determines the file format for saving query results. |
| -h, --help | Displays usage instructions. |
Usage Examples
The following examples shed light on how to use databend-local.
Example 1: Querying from Command-Line
macdeMacBook-Pro:rsdoc eric$ databend-local
Welcome to Databend, version v1.2.100-nightly-29d6bf3217(rust-1.72.0-nightly-2023-09-05T16:14:14.152454000Z).
databend-local:) select max(a) from range(1,1000) t(a);
┌────────────┐
│ max(a) │
│ Int64 NULL │
├────────────┤
│ 999 │
└────────────┘
1 row result in 0.013 sec. Processed 999 rows, 999 B (76.89 thousand rows/s, 600.67 KiB/s)
Example 2: Saving Results to a File
This example demonstrates how to create a Parquet file in a single command.
databend-local --query "select number, number + 1 as b from numbers(10)" --output-format parquet > /tmp/a.parquet
Example 3: Analyzing Data using Shell Pipe Mode
This example demonstrates the use of shell pipe mode to analyze data. The $STDIN macro interprets stdin as a temporary stage table.
echo '3,4' | databend-local -q "select \$1 a, \$2 b from \$STDIN (file_format => 'csv') " --output-format table
SELECT $1 AS a, $2 AS b FROM 'fs:///dev/fd/0' (FILE_FORMAT => 'csv')
┌─────────────────┐
│ a │ b │
│ String │ String │
├────────┼────────┤
│ '3' │ '4' │
└─────────────────┘
Example 4: Reading Staged Files
This example demonstrates how to read data from staged files.
databend-local --query "select count() from 'fs:///tmp/a.parquet' (file_format => 'parquet')"
10
Example 5: Analyzing System Processes
This example is about analyzing system processes to find memory usage per user.
ps aux | tail -n +2 | awk '{ printf("%s\t%s\n", $1, $4) }' | databend-local -q "select \$1 as user, sum(\$2::double) as memory from \$STDIN (file_format => 'tsv') group by user "
_fpsd 0.0
_hidd 0.0
_nearbyd 0.1
_timed 0.0
_netbios 0.0
_trustd 0.1
root 5.899999999999998
_biome 0.1
...
Example 6: Data Transformation
This example demonstrates data transformation from one format to another, supporting formats CSV, TSV, Parquet, and NDJSON.
databend-local -q 'select rand() as a, rand() as b from numbers(100)' > /tmp/a.tsv
cat /tmp/a.tsv | databend-local -q "select \$1 a, \$2 b from \$STDIN (file_format => 'tsv') " --output-format parquet > /tmp/a.parquet