I: What is Zstandard

Zstandard (Zstd) is a new-generation lossless compression algorithm developed and open-sourced by Facebook.

First appearing in 2015, its core value lies in successfully finding an excellent balance between a high compression ratio and extreme decompression speed, making it highly popular within the technical community. Zstd has achieved a breakthrough in compression efficiency compared to traditional tools like Gzip. While ensuring data is highly compressed, it also provides decompression performance that far exceeds comparable algorithms. This makes it perfectly suited for modern application scenarios demanding high throughput, such as ETL processes in large-scale data warehouses, real-time system log management, and high-performance data stream network transmission.

II: Key Features of Zstandard

1: Optimal Performance Balance

Feature	Description	Application Value
High Compression Ratio	In standard tests, Zstd typically offers better compression effectiveness than Gzip.	Effectively reduces storage space and data transfer bandwidth requirements.
Fast Decompression	Possesses extremely fast decompression speeds, potentially far exceeding the sequential read speeds of many SSDs.	Greatly improves data read efficiency and application response speed, especially suitable for read-intensive scenarios.
Multithreading Support	Built-in multithreaded compression functionality that fully utilizes the performance of modern multi-core CPUs, significantly boosting compression throughput.	Significantly shortens waiting times when processing large datasets, increasing work efficiency.

2: Flexible Customization Capabilities

Extensive Compression Level Selection

Zstd offers a wide range of compression levels, from 1 to 22, allowing users to make flexible trade-offs based on specific needs:

Low Levels (1-3): Aim for the fastest compression speed but with a lower compression ratio. Suitable for scenarios requiring real-time compression and low latency (e.g., network transmission).
Medium Levels (4-15): Provide a good balance, serving as the recommended setting for most general-purpose scenarios.
High Levels (16-22): Aim for the highest compression ratio but with the slowest compression speed. Suitable for archival storage where data is compressed once and rarely decompressed.

Dictionary Compression Mode

This is a key feature specifically designed to optimize the compression of small data blocks or numerous small files:

How it Works: Users provide similar sample data for training to generate a dictionary. This dictionary contains the most common data patterns and repeated sequences found in those samples.
Effect: Loading this dictionary during compression and decompression helps the compressor identify repeating patterns even when the data volume is very small (where traditional algorithms struggle), resulting in a higher compression ratio.
Applicable Scenarios: HTTP/HTTPS request headers, small database records, log events, etc.

3: Comprehensive Tools and Ecosystem

Diverse Usage Modes

Zstandard provides mature command-line tools that support various operating modes, making it not just a library but a practical utility:

Basic Operations: Compression (zstd), decompression (unzstd).
Utility Functions: Viewing compressed file information (zstd -l), testing compressed file integrity (zstd -t), etc.

III: Zstandard Installation

The installation command for Debian/Ubuntu systems is as follows:

Bash

sudo apt install zstd

It can also be installed by compiling from source (here using version 1.5.7 as an example):

Bash

wget https://github.com/facebook/zstd/releases/download/v1.5.7/zstd-1.5.7.tar.gz
tar -zxvf zstd-1.5.7.tar.gz
cd zstd-1.5.7/
make
sudo make install

IV: Zstandard (Zstd) Command Line Usage Guide

File Compression

Zstd's basic design makes its usage quite similar to traditional gzip or xz.

Function	Command Line Format	Example	Notes
Basic Compression	`zstd <file_name>`	`zstd data.log`	Generates a `<file_name>.zst` file and deletes the original file by default.
Specify Level	`zstd -<level> <file_name>`	`zstd -10 report.pdf`	Levels range from 1 (fastest) to 22 (highest compression ratio).
Keep Original File	`zstd -k <file_name>`	`zstd -k big_data.csv`	Uses the `-k` (keep) option to retain the original file after compression.
Specify Output Name	`zstd -c <file_name> > <output_name>.zst`	`zstd -c source.txt > target.zst`	Uses standard output (`-c`), often used for piping or specifying the output filename.

File Decompression

Zstd offers various decompression command forms, but the core involves using the -d option or directly calling the unzstd command.

Function	Command Line Format	Example	Notes
Basic Decompression	`zstd -d <archive_name>.zst`	`zstd -d backup.zst`	Deletes the `.zst` file by default after decompression.
Decompress and Keep	`zstd -d -k <archive_name>.zst`	`zstd -d -k archive.zst`	Uses the `-k` (keep) option to retain the compressed `.zst` file.
Specify Output Name	`zstd -d -o <new_file> <archive_name>.zst`	`zstd -d -o final.txt compressed.zst`	Uses the `-o` (output) option to specify the decompressed filename.
Equivalent Command	`unzstd <archive_name>.zst`	`unzstd backup.zst`	The `unzstd` command is equivalent to `zstd -d`.

Directory and Recursive Operations

Zstd is fundamentally a file compression utility. To process directories, it introduces the recursive (-r) option.

Function	Command Line Format	Example	Notes
Compress Directory	`zstd -r <directory_name>`	`zstd -r logs_2023`	Recursively processes all files and subdirectories, generating a separate `.zst` file for each file.
Decompress Directory	`zstd -dr <archive_name>.zst`	`zstd -dr logs_2023.zst`	ERROR! Zstd's recursive mode does not package the entire directory into a single `.zst` file.
Correct Decompression	`zstd -r -d <directory_name>`	`zstd -r -d logs_2023`	Used to batch decompress multiple `.zst` files within a directory.

Best Practice:
Since zstd -r only compresses each file within the directory individually, if you need to package the entire directory into a single compressed file, you should first use the tar utility for packaging, and then compress with Zstd:
# Package and Compress: Packages the entire /my_dir directory and compresses it with Zstd
tar -I zstd -cf my_dir.tar.zst /my_dir
Decompress:
tar -I zstd -xf my_dir.tar.zst

Information Viewing and Verification

Function	Command Line Format	Example	Purpose
View Information	`zstd -l <archive_name>.zst`	`zstd -l data.zst`	Lists relevant information about the compressed file, including compression level, original size, compressed size, and compression ratio.
Test Integrity	`zstd -t <archive_name>.zst`	`zstd -t archive.zst`	Tests whether the compressed file is complete and decompressible, without performing actual decompression. Often used to verify file integrity after transfer.

Conclusion

The above covers all the information shared today, summarized from my research and daily usage. Some aspects may not be entirely comprehensive.