I’m having trouble understanding the intent of the start and count arguments to SUBSTR in the SCRUB_EMAIL function . I understand that we want to return the first five or more characters from the MD5 value. The PostgreSQL documentation examples indicate that string indexes start at 1, not 0. Why doe…

Hi @douglasshuang . Thanks for the detailed write-up again here. I don’t remember for sure whether I knew functions like substring() had 1-based indexes and not 0-based. I studied that documentation page and didn’t explicitly see it mentioned, however it can be deduced from the examples, for example…

High Performance PostgreSQL for Rails: Confusing `SUBSTR` arguments in `SCRUB_EMAIL` (page 52)

Pragmatic Bookshelf PragProg Customers

douglasshuang 5 May 2025 13:49 3

Hi @andatki, that sounds good. Thank you!

1 Like