Usage

zstd_compress compresses the provided data and returns a Zstandard frame. A preset dictionary may also be provided. The default compression level may also be overriden, valid values range from 1 (best speed) to 22 (best compression). The default level is 3.

If you want to override the compression level without using a dictionary, set dictionary to NULL.

zstd_decompress decompresses the provided Zstandard frame in data and returns the uncompressed data. A preset dictionary, matching the dictionary used to compress the data, may also be provided.

zstd_length returns the decompressed length of the provided Zstandard frame. If ZSTD_getFrameContentSize() is available it returns NULL if the length is unknown. If unavailable, it isn’t possible to distinguish the error, unknown decompressed length and zero decompressed length cases.

Example

Basic compress/decompress example:

CREATE EXTENSION zstd;

SELECT zstd_compress('hello world');
-- zstd_compress
-- --------------------------------------------
-- \x28b52ffd200b59000068656c6c6f20776f726c64

SELECT convert_from(zstd_decompress('\x28b52ffd200b59000068656c6c6f20776f726c64'), 'utf-8');
-- convert_from
-- --------------
--  hello world

Compress with level (1 for best speed, 22 for best compression, default to 3)

CREATE EXTENSION zstd;

SELECT zstd_compress('hello world',  NULL, 10);
-- zstd_compress
-- --------------------------------------------
-- \x28b52ffd200b59000068656c6c6f20776f726c64

SELECT convert_from(zstd_decompress('\x28b52ffd200b59000068656c6c6f20776f726c64'), 'utf-8');
-- convert_from
-- --------------
--  hello world