Created
May 4, 2021 18:45
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postgresql_hashes_stored_as_binary_cheatsheet.sql
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WITH xs as ( | |
select '' as x -- empty string | |
union all select 'a' -- lowercase letter | |
union all select 'A' -- uppercase | |
union all select 'aa' -- two ascii letters | |
union all select 'á' -- 'a' with accent | |
union all select '的' -- one CJK character, stored as multiple bytes | |
union all select 'deadbeef' | |
union all select 'DEADBEEF' | |
) | |
select | |
x | |
, length(x) as readable_char_len | |
, octet_length(x) as byte_len | |
-- , md5(x)::bytea as md5_bin_THIS_IS_WRONG | |
, decode(md5(x), 'hex') as md5_bin -- RIGHT | |
, octet_length(decode(md5(x), 'hex')) as md5_bin_bytelen | |
, encode(decode(md5(x), 'hex'),'hex') as md5hex_to_md5bin_to_md5hex_roundtrip | |
, md5(x) as md5_hex | |
, md5(x)=encode(decode(md5(x), 'hex'),'hex') unittest | |
from xs | |
; |
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