PartiQL Identifier - Variable Binding and Variable Look Up.

[yliuuuu]

Related Issues:

• Revisit case sensitivity of identifiers partiql-lang-kotlin#1122

Variable Binding

For variable binding, case insensitivity identifier are not normalized, and the exact text was used to track identifier in environment as defined in PartiQL specification.

Variable Look up

The implementation of PartiQL-Lang-Kotlin uses a "match" strategy for variable look up.

match(id, env) = {
   env.get(DIB(id)) if id is a delimited identifier
   env.get(id, ignoreCase) if id is a regular identifier
} 

Note: env.get(id, ignoreCase) will attempts to compare each key with id 
regardless of the case. 

In other word: For each key: it compares upper(key) with upper(id)

This match strategy is not conformant to behavior defined in the SQL specification for case insensitive identifier.

We need to decided if we want to :

1. Keep the current behavior, and specify and stabilize it.
2. Switch to the behavior defined by SQL.
3. Switch to case sensitive identifier, in which case the double quoted identifier is only for escaping special character and reserved word.

DoD:

• A RFC on PartiQL Identifier is published, reviewed, and merged.
• Implementation of PartiQL-Lang-Kotlin and PartiQL-Lang-Rust is changed according to the specification.