This Week in Databend #139

Databend is a modern cloud data warehouse, serving your massive-scale analytics needs at low cost and complexity. Open source alternative to Snowflake. Also available in the cloud: https://app.databend.com .

What's New

Stay informed about the latest features of Databend.

Supporting `CHANGES` Clause

Databend now supports the CHANGES clause, which is used for retrieving metadata about changes across transaction boundaries.

The CHANGES clause allows querying the metadata of changes in tables over specified intervals without the need to create streams with explicit transaction offsets.

bendsql> select * from t changes(information => default) at (stream => s) order by a, b;
+------+------+---------------+----------------------------------------+------------------+
| a    | b    | change$action | change$row_id                          | change$is_update |
+------+------+---------------+----------------------------------------+------------------+
|    2 |    1 | DELETE        | d60dab8545424894ba9ea2cb0baad51e000001 |                1 |
|    2 |    2 | INSERT        | d60dab8545424894ba9ea2cb0baad51e000001 |                1 |
|    3 |    3 | INSERT        | 8ba7cb6acc7e4dd5aab03f9d32e0ccb8000000 |                0 |
+------+------+---------------+----------------------------------------+------------------+

bendsql> select * from t changes(information => append_only) at (stream => s) order by a, b;
+------+------+---------------+------------------+----------------------------------------+
| a    | b    | change$action | change$is_update | change$row_id                          |
+------+------+---------------+------------------+----------------------------------------+
|    3 |    3 | INSERT        |                0 | 8ba7cb6acc7e4dd5aab03f9d32e0ccb8000000 |
+------+------+---------------+------------------+----------------------------------------+

Here, INFORMATION => { DEFAULT | APPEND_ONLY } specifies the type of tracking data:

DEFAULT is like a standard stream, tracking insertions, deletions, and updates.
APPEND_ONLY is like an append-only stream, tracking only the appended rows.

If you would like to learn more, please contact the Databend team or refer to the resources listed below:

PR | feat(query): support CHANGES clause

Code Corner

Discover some fascinating code snippets or projects that showcase our work or learning journey.

Databend X Open Source Promotion Plan, Stay Tuned

Open Source Promotion Plan is a summer program organized by the Institute of Software Chinese Academy of Sciences and long-term supported by the Open Source Software Supply Chain Promotion Plan. It aims to encourage college students to actively participate in the maintenance and development of open source software, promote the vigorous development of open source software communities, and build the open source software supply chain together.

This year marks Databend's third participation in the OSPP event. We welcome students interested in the community to stay tuned as we are actively preparing project topics.

OSPP 2024 - Databend

Highlights

We have also made these improvements to Databend that we hope you will find helpful:

Added support for the ST_GEOMFROMGEOHASH GEO function.
The RANDOM engine now supports setting a random seed.
Added support for using expressions in the VALUES clause of multi-table inserts.
Read the blog Databend Integrates PRQL: A Small Step for Modern Data Processing to learn about Databend's PRQL integration.

What's Up Next

We're always open to cutting-edge technologies and innovative ideas. You're more than welcome to join the community and bring them to Databend.

Adding More Useful Commands to BendSQL

BendSQL is an interactive command-line tool designed specifically for Databend and Databend Cloud. We plan to add more useful commands to further enhance its usability and improve user experience.

Currently supported commands include:

Commands	Description
`!exit`	Exit bendsql
`!quit`	Exit bendsql
`!configs`	Show current settings
`!set`	Set settings
`!source file`	Source file and execute

Issue bendsql#354 | Useful commands

Please let us know if you're interested in contributing to this feature, or pick up a good first issue at https://link.databend.rs/i-m-feeling-lucky to get started.