Hashids is a small open-source library that generates short, unique, non-sequential ids from numbers. It converts numbers like 347 into strings like “yr8”. You can also decode those ids back. This is useful in bundling several parameters into one or simply using them as short UIDs.

You can use hashids to hide primary keys in your database.

More information about hashids and it's implementations can be found here: hashids.org

Suitable for hosted environments like AWS RDS.

But if you are looking for an PG extention, then please check out pg_hashids repository.

Returns a hash using the default alphabet and specified min_length and salt parameters.

select hashids.encode( number := 999, min_length := 6, salt := 'salt'); -- dkrMl8

number parameter can also be an array of numbers:

select hashids.encode( number := array[111,222], min_length := 6, salt := 'salt'); -- VyAHPK

It's also could be helpful to use it with sequences:

select hashids.encode( number := nextval('schema.sequence_name'), min_length := 6, salt := 'salt');

You can also decode previously generated hashes. Just use the same parameters salt, min_length and alphabet, otherwise you'll get wrong results.

select hashids.decode( id := 'dkrMl8', min_length := 6, salt := 'salt'); -- {999}
select hashids.decode( id := 'VyAHPK', min_length := 6, salt := 'salt'); -- {111,222}

Using custom alphabet, only capitalized letters and numbers:

select hashids.encode( number := 999, salt := 'salt', alphabet := 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890'); -- D3Q5

Useful if you want to encode Mongo's ObjectIds. Note that there is no limit on how large of a hex number you can pass (it does not have to be Mongo's ObjectId).

select hashids.encode_hex( hex := '507f1f77bcf86cd799439011', salt := 'salt'); -- zro2yr9M4ZCzZ9zd9xYv

These ids can be also easily decoded back to their original values:

select hashids.decode_hex( id := 'zro2yr9M4ZCzZ9zd9xYv', salt := 'salt'); -- 507f1f77bcf86cd799439011