Re: Re: proposal: schema variables

Hi

so 28. 12. 2024 v 17:47 odesílatel jian he <jian(dot)universality(at)gmail(dot)com>
napsal:

> hi.
>
> + if (stmt->collClause)
> + collation = LookupCollation(pstate,
> + stmt->collClause->collname,
> + stmt->collClause->location);
> + else
> + collation = typcollation;;
>
> two semi-colon. should be only one.
>

removed

> ------------------<<>>>---------------
> + /* locks the variable with an AccessShareLock */
> + varid = IdentifyVariable(names, &attrname, &not_unique, false);
> + if (not_unique)
> + ereport(ERROR,
> + (errcode(ERRCODE_AMBIGUOUS_PARAMETER),
> + errmsg("target \"%s\" of LET command is ambiguous",
> + NameListToString(names)),
> + parser_errposition(pstate, stmt->location)));
>
> the following are tests for the above "LET command is ambiguous" error
> message.
>
> create schema test;
> CREATE TYPE test AS (test int);
> CREATE variable test.test as test;
> set search_path to test;
> let test.test = 1;
>

done

------------------<<>>>---------------
> + else
> + {
> + /* the last field of list can be star too */
> + Assert(IsA(field2, A_Star));
> +
> + /*
> + * In this case, the field1 should be variable name. But
> + * direct unboxing of composite session variables is not
> + * supported now, and then we don't need to try lookup
> + * related variable.
> + *
> + * Unboxing is supported by syntax (var).*
> + */
> + return InvalidOid;
> + }
> I don't fully understand the above comments,
>

The parser allows only two syntaxes - identifier.identifier or
identifier.star. Second
syntax is not supported by session variables, and then I didn't try to
search for the variable.
Some users can be confused by similar syntaxes identifier.* and
(identifier).* Only
second syntax is composite unboxing, and only second syntax is supported for
session variables.

Maybe the note about unboxing is messy there?

add
> `elog(INFO, "%s:%d called", __FILE__, __LINE__); ` within the ELSE branch.
> Then I found out the ELSE branch doesn't have coverage tests.
>

I don't understand this comment? I don't use elog(INFO anywhere

>
> ------------------<<>>>---------------
> + /*
> + * a.b.c can mean catalog.schema.variable or
> + * schema.variable.field.
> ....
> + /*
> + * a.b can mean "schema"."variable" or "variable"."field".
> + * Check both variants, and returns InvalidOid with
> + * not_unique flag, when both interpretations are
> + * possible.
> + */
> here, we use the word "field", but the function IdentifyVariable above
> comment, we use
> word "attribute", for consistency's sake, we should use "attribute"
> instead of "field"
>

done

>
> +/* -----
> + * IdentifyVariable - try to find a variable from a list of identifiers
> + *
> + * Returns the OID of the variable found, or InvalidOid.
> + *
> + * "names" is a list of up to four identifiers; possible meanings are:
> + * - variable (searched on the search_path)
> + * - schema.variable
> + * - variable.attribute (searched on the search_path)
> + * - schema.variable.attribute
> + * - database.schema.variable
> + * - database.schema.variable.attribute
>
> ------------------<<>>>---------------
>

updated patchset assigned

Thank you very much for review

Regards

Pavel