Hemil: On Wed, Oct 7, 2020 at 2:49 PM Hemil Ruparel <hemilruparel2002@xxxxxxxxx> wrote: > I was integrating a payment gateway for my app when I noticed its maximum length of customer id string is 32. SIze of UUID is 36 (32 characters and 4 dashes). So I want to change the type of customer id to serial. The problem is by now, the column is being used at many places. How to migrate the column to serial without dropping the data? An uuid is just a 128 bit number, as noted by many. Your problem is the default encoding is 32 hex digits plus 4 hyphens. If your payment gateway uses a 32 CHARs string ( "maximum length of customer id string is 32" ) you can just use other encodings. Passing to integer and using decimal wont cut it ( you'll need 39 digits ), but using just hex (without hyphens) will drop the string representation to 32 characters ( you can encode with a subst and postgres accepts it without hyphens ). If you want to buy a little more space for your own purposes you can even fit 128 bits in 22 base64 chars with a couple pairs of bits to spare, and IIRC you can do it with a creative decode/encode step after killing the dashes. And if your payment gateway uses unicode codepoints instead of ASCII chars as units you could probably use more creative encodings ;-) , but probably using a "drop the dashes" subst in the interface will be your simpler option. Francisco Olarte.
