How to Efficiently Store SHA1 Hash Values in MySQL?

Storing SHA1 Hash Values in MySQL Efficiently

When storing the result of a SHA1 hash in a MySQL database, a common question arises regarding the optimal field length.

Determining Field Length

Avoid using VARCHAR for fixed-length data like SHA1 hashes, as it introduces overhead. Instead, opt for a BINARY field of appropriate length.

Efficient Storage

SHA1 hashes are 160 bits long. To store this in binary format, we need 20 bytes (160/8). Using the UNHEX function to convert SHA1 values to binary allows for more compact storage.

Space Optimization

BINARY(20) requires less storage space compared to CHAR(40). For example, with a million records, BINARY(20) takes up 44.56M of storage, while CHAR(40) consumes 64.57M. This optimization becomes significant in large databases.

Recommendation

To efficiently store SHA1 hash values in MySQL, it is recommended to use BINARY(20) and convert the hashes to binary format using the UNHEX function. This provides both compactness and space optimization.

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