DuckDB fnv partitioner extension

Implements duckdb user defined functions for FNV hash and partitioning. It exposes two functions:

• fnv() - Takes a string and returns the FNV hash of the string.
• fnv_partition() - Takes a string and max partitions and returns the partition number.

Usage

$ wget https://github.com/joeirimpan/duckdb-fnv/releases/download/v0.0.1/fnv.duckdb_extension -O /path/to/file/fnv.duckdb_extension
$ duckdb -unsigned
v1.0.0 1f98600c2c
Enter ".help" for usage hints.
D LOAD '/path/to/file/fnv.duckdb_extension';
D select fnv('joeirimpan');
┌───────────────────┐
│ fnv('joeirimpan') │
│       int32       │
├───────────────────┤
│        1875971319 │
└───────────────────┘
D select fnv_partition('joeirimpan', 420);
┌──────────────────────────────────┐
│ fnv_partition('joeirimpan', 420) │
│              int32               │
├──────────────────────────────────┤
│                              159 │
└──────────────────────────────────

Development

To build the extension, follow these steps:

1. Run the command make in the terminal.

The main binaries that will be built are:

• ./build/release/duckdb: The binary for the duckdb shell with the extension code automatically loaded.
• ./build/release/test/unittest: The test runner of duckdb. The extension is already linked into the binary.
• ./build/release/extension/fnv/fnv.duckdb_extension: The loadable binary as it would be distributed.

Building for linux_amd64_gcc4 platform

To build the extension for linux_amd64_gcc4, follow these steps:

1. docker build -t duckdb_fnv .
2. docker run --rm duckdb_fnv cat /build/release/extension/fnv/fnv.duckdb_extension > fnv.duckdb_extension

Running the extension

To run the extension code, follow these steps:

1. Start the shell with ./build/release/duckdb. This shell will have the extension pre-loaded.

Now you can use the features from the extension directly in DuckDB. The template contains a scalar function fnv() that takes a string argument and max partitions, and returns an integer.

Example usage:

SELECT fnv('joeirimpan') AS hash;

This will return:

┌───────────────┐
│     hash      │
│     int       │
├───────────────┤
│  1875971319   │
└───────────────┘

SELECT fnv_partition('joeirimpan', 32) AS partition;

This will return:

┌───────────────┐
│   partition   │
│     int       │
├───────────────┤
│      23       │
└───────────────┘