Bug Report: vtexplain with sequence does not work when the vitess_sequence is used with uppercase COMMENT #14941

Overview of the Issue

If you have a sequence definition like:

CREATE TABLE t1_seq (
        id bigint unsigned NOT NULL,
        next_id bigint unsigned,
        cache bigint unsigned,
        PRIMARY KEY (id)
) COMMENT 'vitess_sequence';

and the associated vschema to use it, when you try and plan an INSERT query using the sequence via vtexplain, you will get an error like:

target: unsharded.-.primary: t1_seq is not a sequence

Scratched my head about this for a bit, but if you look at the code for checking the sequence comment, the problem becomes clearer:

https://github.com/vitessio/vitess/blob/release-18.0/go/vt/vtexplain/vtexplain_vttablet.go#L426

We check for comment (lowercase); and the option.Name values are not normalized. The problem is therefore the capitalization. Using the following sequence definition therefore works:

CREATE TABLE t1_seq (
        id bigint unsigned NOT NULL,
        next_id bigint unsigned,
        cache bigint unsigned,
        PRIMARY KEY (id)
) comment 'vitess_sequence';

Reproduction Steps

See above.

Binary Version

release-18.0 main branch;  but this affects all Vitess versions since the support was merged from https://github.com/vitessio/vitess/pull/7186

Operating System and Environment details

Linux x86_64

Log Fragments

No response