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Load Data From Local File System

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Databend offers the Streaming Load API that lets you load data from your local files.

Streaming Load API​

The Streaming Load API is used to read data from your local files in one of the following formats and loads it into Databend:

  • CSV (UTF-8 encoded)
  • TSV
  • JSON
  • NDJSON
  • Parquet

API Request Format​

To create a request with the Streaming Load API, follow the format below:

curl -H "<parameter>:<value>"  [-H "<parameter>:<value>"...] -F "upload=@<file_location>" -XPUT http://<user_name>:[password]@<http_handler_host>:<http_handler_port>/v1/streaming_load

Explaining Argument -H​

The request usually includes many occurrences of the argument -H and each is followed by one of the following parameters to tell Databend how to handle the file you're loading data from:

ParameterValuesSupported FormatsExamples
insert_sql[INSERT_statement] + format [file_format]All-H "insert_sql: insert into ontime format CSV"
format_skip_headerTells Databend how many lines at the beginning of the file to skip for header.
0 (default): No lines to skip;
1: Skip the first line;
N: Skip the first N lines.		CSV / TSV / JSON / NDJSON-H "format_skip_header: 1"
format_compressionTells Databend the compression format of the file.
NONE (default): Do NOT decompress the file;
AUTO: Automatically decompress the file by suffix;
You can also use one of these values to explicitly specify the compression format: GZIP | BZ2 | BROTLI | ZSTD | DEFALTE | RAW_DEFLATE.		CSV / TSV / JSON / NDJSON-H "format_compression:auto"
format_field_delimiterTells Databend the characters used in the file to separate fields.
Default for CSV files: ,.
Default for TSV files: \t.		CSV / TSV-H "format_field_delimiter:,"
format_record_delimiterTells Databend the new line characters used in the file to separate records.
Default: \n.		CSV / TSV-H "format_recorder_delimiter:\n"
format_quote_charTells Databend the quote characters for strings in CSV file.
Default: :.		CSV

Tutorial 1 - Load from a CSV File​

This tutorial takes a CSV file as an example, showing how to load data into Databend from a local file.

Before You Begin​

Download the sample CSV file books.csv. The sample contains the following records:

Transaction Processing,Jim Gray,1992
Readings in Database Systems,Michael Stonebraker,2004

Step 1. Create Database and Table​

mysql -h127.0.0.1 -uroot -P3307
CREATE DATABASE book_db;
USE book_db;

CREATE TABLE books
(
    title VARCHAR,
    author VARCHAR,
    date VARCHAR
);

Step 2. Load Data into Table​

Create and send the API request with the following scripts:

curl -XPUT 'http://root:@127.0.0.1:8081/v1/streaming_load' -H 'insert_sql: insert into book_db.books format CSV' -H 'skip_header: 0' -H 'field_delimiter: ,' -H 'record_delimiter: \n' -F 'upload=@"./books.csv"'

Response Example:

{
  "id": "f4c557d3-f798-4cea-960a-0ba021dd4646",
  "state": "SUCCESS",
  "stats": {
    "rows": 2,
    "bytes": 157
  },
  "error": null,
  "files": ["books.csv"]
}

Step 3. Verify Loaded Data​

SELECT * FROM books;

+------------------------------+----------------------+-------+
| title                        | author               | date  |
+------------------------------+----------------------+-------+
| Transaction Processing       |  Jim Gray            |  1992 |
| Readings in Database Systems |  Michael Stonebraker |  2004 |
+------------------------------+----------------------+-------+

Tutorial 2 - Load into Specified Columns​

In Tutorial 1, you created a table containing three columns that exactly match the data in the sample file. The Streaming Load API also allows you to load data into specified columns of a table in Databend, so the table does not need to have the same columns as the data to be loaded as long as the specified columns can match. This tutorial shows how to do that.

Before You Begin​

Before you start this tutorial, make sure you have completed Tutorial 1.

Step 1. Create Table​

Create a table including an extra column named "comments" compared to the table "books":

CREATE TABLE bookcomments
(
    title VARCHAR,
    author VARCHAR,
    comments VARCHAR,
    date VARCHAR
);

Step 2. Load Data into Table​

Create and send the API request with the following scripts:

curl -XPUT 'http://root:@127.0.0.1:8081/v1/streaming_load' -H 'insert_sql: insert into book_db.bookcomments(title,author,date)format CSV' -H 'skip_header: 0' -H 'field_delimiter: ,' -H 'record_delimiter: \n' -F 'upload=@"./books.csv"'

Notice that the insert_sql part above specifies the columns (title, author, and date) to match the loaded data.

Step 3. Verify Loaded Data​

SELECT * FROM bookcomments;

+------------------------------+----------------------+----------+--------+
| title                        | author               | comments | date   |
+------------------------------+----------------------+----------+--------+
| Transaction Processing       |  Jim Gray            |          |  1992  |
| Readings in Database Systems |  Michael Stonebraker |          |  2004  |
+------------------------------+----------------------+----------+--------+