[typeid-sql] Fix typos and clarify usage of different encodings in README (#378)

## Summary
Fix typos and clarify usage of different encodings in README

## How was it tested?
N/A

Author: loreto

README.md

@@ -25,52 +25,94 @@ for development and testing, but you do **not** need to use Supabase for this
 implementation to work – simply use the Postgres instance of your choice.
 
 ## Usage
-
 Once you've installed the TypeID types and functions in your Postgres instance,
-you can use it as follows.
+you have two options on how to encode TypeIDs in your database.
+
+### 1. Text-based encoding
+This encoding is more inefficient than the alternative, but it's very straight-forward
+to understand, it's easy to debug by simply inspecting the contents of your tables, and
+it works well with other tools you might be using to inspect your database.
 
-To define a new type of typeid with a specific prefix use the `typeid\_
+To use it:
++ Declare your `id` column using the `text` type.
++ Use the `typeid_generate_text` function to generate new default values.
++ Use the `typeid_check_text` to enforce all strings in the column are valid typeids.
+
+Example:
 
 ```sql
 -- Define a `users` table that uses `user_id` as its primary key.
--- We use the `typeid_generate` function to randomly generate a new typeid of the
+-- We use the `typeid_generate_text` function to randomly generate a new typeid of the
 -- correct type for each user.
+-- We also recommend adding the check constraint to the column
 CREATE TABLE users (
-    "id" user_id not null default typeid_generate('user'),
+    "id" text not null default typeid_generate_text('user') CHECK (typeid_check_text(id, 'user')),
     "name" text,
     "email" text
 );
 
--- Now we can insert new uses and have the `id` column automatically generated.
+-- Now we can insert new users and have the `id` column automatically generated.
 INSERT INTO users ("name", "email") VALUES ('Alice P. Hacker', 'alice@hacker.net');
+SELECT id FROM users;
+-- Result:
+-- "user_01hfs6amkdfem8sb6b1xmg7tq7"
+
+-- Insert a user with a specific typeid that might have been generated elsewhere:
+INSERT INTO users ("id", "name", "email")
+VALUES ('user_01h455vb4pex5vsknk084sn02q', 'Ben Bitdiddle', 'ben@bitdiddle.com');
+
+-- To retrieve the ids as encoded strings, just use the column:
+SELECT id AS id, "name", "email" FROM users;
+
+-- You can also use filter in a WHERE clause to filter by typeid:
+SELECT typeid_print(id) AS id, "name", "email" FROM users
+WHERE id = 'user_01h455vb4pex5vsknk084sn02q';
 ```
 
-Or
+### 2. UUID-based encoding using compound types
+In this approach, we internally encode typeids as a `(prefix, uuid)` tuple. The
+sql files in this library provide a predefined `typeid` type to represent
+said tuples.
+
+The advantage of this approach is that it is a more efficient encoding because we
+store the uuid portion of the typeid using the native `uuid` type.
 
-You can use the typeid_generate_text function to generate a new typeid as a string, and not use the typeid type
+The disadvanage is that it is harder to work with and debug.
+
+If performance is a primary concern of yours, also consider using the native
+[postgres extension](https://github.com/blitss/typeid-postgres) for typeid,
+which exposes typeids as a "built-in" type.
+
+To define a new typeid using this encoding, you can use the `typeid_check` function:
+```sql
+-- Define a `user_id` type, which is a typeid with type prefix "user".
+-- Using `user_id` throughout our schema, gives us type safety by guaranteeing
+-- that the type prefix is always "user".
+CREATE DOMAIN user_id AS typeid CHECK (typeid_check(value, 'user'));
+```
+
+You can now use the newly defined type in your tables. The `typeid_generate` function
+makes it possible to automatically a new random typeid for each row:
 
 ```sql
 -- Define a `users` table that uses `user_id` as its primary key.
--- We use the `typeid_generate_text` function to randomly generate a new typeid of the
+-- We use the `typeid_generate` function to randomly generate a new typeid of the
 -- correct type for each user.
--- You will need to manually add the check constraint to the column
 CREATE TABLE users (
-    "id" text not null default typeid_generate_text('user') CHECK (typeid_check_text(id, 'user')),
+    "id" user_id not null default typeid_generate('user'),
     "name" text,
     "email" text
 );
 
--- Now we can insert new uses and have the `id` column automatically generated.
+-- Now we can insert new users and have the `id` column automatically generated.
 INSERT INTO users ("name", "email") VALUES ('Alice P. Hacker', 'alice@hacker.net');
-SELECT id FROM users;
--- Result:
--- "user_01hfs6amkdfem8sb6b1xmg7tq7"
 ```
+#### Querying
+To make it easy to query typeid tuples using the standard string representation, we
+provide two convenience functions: `typeid_parse` and `typeid_print`, which convert
+to and from the standard string representation.
 
-Note that the database internally encodes typeids as a `(prefix, uuid)` tuple. Because
-this is different than the standard string representation of typeids in other libraries,
-we provide a `typeid_parse` and a `typeid_print` function that can be used to write
-queries with the standard string representation of typeids:
+Example:
 
 ```sql
 -- Insert a user with a specific typeid that might have been generated elsewhere:
@@ -85,22 +127,7 @@ SELECT typeid_print(id) AS id, "name", "email" FROM users
 WHERE id = typeid_parse('user_01h455vb4pex5vsknk084sn02q');
 ```
 
-or for the text variant
-
-```sql
--- Insert a user with a specific typeid that might have been generated elsewhere:
-INSERT INTO users ("id", "name", "email")
-VALUES ('user_01h455vb4pex5vsknk084sn02q', 'Ben Bitdiddle', 'ben@bitdiddle.com');
-
--- To retrieve the ids as encoded strings, just use the column:
-SELECT id AS id, "name", "email" FROM users;
-
--- You can also use filter in a WHERE clause to filter by typeid:
-SELECT typeid_print(id) AS id, "name", "email" FROM users
-WHERE id = 'user_01h455vb4pex5vsknk084sn02q';
-```
-
-## (Optional) Operator overload
+#### (Optional) Operator overload
 
 If you'd like to be able to do the following:
 
@@ -112,7 +139,10 @@ SELECT * FROM users u WHERE u.id = 'user_01h455vb4pex5vsknk084sn02q';
 -- "(user,018962e7-3a6d-7290-b088-5c4e3bdf918c)",Ben Bitdiddle,ben@bitdiddle.com
 ```
 
-Then you can add in [the operator overload function for typeids](https://github.com/search?q=repo%3Ajetify-com%2Ftypeid-sql%20compare_type_id_equality&type=code):
+Then you can add in [the operator overload functions for typeid](https://github.com/jetify-com/typeid-sql/blob/main/sql/04_operator.sql).
+
+Some users have reported issues with the above operator when using Rails and ActiveRecord – we
+recommend removing `COMMUTATOR` from the operator definition if you encounter issues.
 
 ## Future work (contributions welcome)