> doing a tolower() on every db search and not use indices
If you create the index with lower() it will uses that; e.g. "create index on tbl (lower(email))" and then "select * from tbl where lower(email)=lower($1)". That's more or less the standard way to do this but there are some other ways as well. It's more explicit than MySQL, so in that way it's better. It's more effort and easy to forget, and in that way it's worse – either way: it's definitely possible to do case-insensitive searches with indexes.
When I first used PostgreSQL I ran in to "how the hell do I do this?! MySQL just lets me [...]" kind of issues, but after many years of PostgreSQL usage I now have the opposite when I use MariaDB, which also has its share of awkwardness and issues (just different ones).
> It's more explicit than MySQL, so in that way it's better.
It sounds like you're under the impression that MySQL just makes everything case-insensitive and is silent about this? That's decidedly not the case.
MySQL 8 ships with 41 different character sets, supporting a total of 286 different collations. Collation names explicitly include "ci" (case-insensitive) vs "cs" (case-sensitive), as well as "ai" (accent-insensitive) vs "as" (accent-sensitive), and also the language/region conventions used for sorting purposes.
You can choose collation at the column-level granularity, as well as setting defaults at the table, schema, and server levels. It's completely explicit and very configurable.
Eh, just from a SQL query alone, there's no way to see that (lower(email)) is indexed, or see column data types etc. That metadata lives in the table definition, which is a normal place for it, so it seems reasonable for the collation / case-insensitivity to not be explicit in the query text.
Besides, MySQL also supports functional indexes, so you could do the (lower(email)) approach in MySQL too if you really want!
No, you can't see everything, but you can see the exact comparison it's making. Is that useful? You can decide that for yourself but I like being able to see as much of the logic (and thus verify the correctness) in the query itself. Also helps with copy/paste and some other things.
I never said you can't use functional indexes in MySQL. Someone said "you can't do this in PostgreSQL" and I just commented "here's (one way) to do this, maybe that's helpful some day". That's it.
I was disappointed with MariaDB and tried it before using MySQL. It is so far behind MySQL that it can't be considered equivalent anymore. And I really wanted to use MariaDB instead.
The "MySQL just lets me" stuff eventually adds up and hinders development. For example, your lower() on the param example is now incompatible with most ORMs unless you do that in code or create a special SQL statement for that. This isn't all fringe cases that you run into when you're months in either. I really wonder on some of these comments saying they've vetter both and Postgres wins hands down.
Postgres is solid but it definitely has its warts and downsides too.
If you create the index with lower() it will uses that; e.g. "create index on tbl (lower(email))" and then "select * from tbl where lower(email)=lower($1)". That's more or less the standard way to do this but there are some other ways as well. It's more explicit than MySQL, so in that way it's better. It's more effort and easy to forget, and in that way it's worse – either way: it's definitely possible to do case-insensitive searches with indexes.
When I first used PostgreSQL I ran in to "how the hell do I do this?! MySQL just lets me [...]" kind of issues, but after many years of PostgreSQL usage I now have the opposite when I use MariaDB, which also has its share of awkwardness and issues (just different ones).