Add ConnectorIdentifier to Connector

[prrvchr]

Description

I am trying to add a functional comparator for identifiers that support delimiters.
The new class ConnectorIdentifier is intended to do so. It also allows the connector to know whether the DDL commands for which it is responsible should be executed with delimited identifiers or not.

Additional context and related issues

• This should resolve Connectors need to know whether an identifier is delimited or not #28356

Release notes

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## Section
* Fix some things. ({issue}`28356`)

[prrvchr]

@wendigo Here's how it's possible to switch to mixed case with Trino while maintaining a minimum of backward compatibility. This requires more changes than expected and is only implemented for views.
Thanks for your feedback.

[martint]

Names coming from connectors don't have a delimited / non-delimited characteristic. They are already canonicalized. The delimited characteristic only pertains to identifiers parsed from a SQL query, and matters only for deciding how to match identifiers to names.

[prrvchr]

Names coming from connectors don't have a delimited / non-delimited characteristic.

Regarding the identifiers coming from the connectors, I agree. But here we're talking about identifiers coming from Trino tasks and destined for the connectors in order to execute the appropriate DDL commands.

If we want to be able to manage delimited and undelimited identifiers and compare them according to the underlying database rules. For example:

• in HsqlDB (uppercase) "PUBLIC".Table1 is the same identifier as public."TABLE1"

• in SQLite (lowercase) "main".Table1 is the same identifier as MAIN."table1"

If we need to test whether a schema exists before its creation, I don't see any other way without using the ConnectorIdentifier class, which allows these comparisons between identifiers.

I'd like you to explain how you plan to solve this problem, because so far I haven't found anything better?

[prrvchr]

@martint I think I understand what you were trying to tell me.

You're saying that Trino must normalize (ie: canonalize) all undelimited identifiers and that, therefore, all identifiers received by connectors must be considered as delimited identifiers.

Can you confirm this? Please excuse my lack of understanding.

[prrvchr]

I got a little sidetracked, I'm closing this.