Can I use VARCHAR(32) for md5() values?

Since md5 always produces fixed length result, better use CHAR(32)

Better to use CHAR(32) with latin1 charset, or BINARY(16) if you want to save more spaces.

CREATE TABLE ... (    ...    md5 CHAR(32) CHARACTER SET 'latin1' NOT NULL    ...

MySQL uses utf8mb4 as default charset since 5.7, and CHAR(32) with utf8mb4 takes 128 bytes, worse than VARCHAR(32).

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