Partial fix optional match 4745

[xtcyclist]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

#4745

Description:

The where clause is omitted in a singular optional match, resulting in wrong responses.

How do you solve it?

• Added a seperate if-scope to prevent singular optional matches producing random results.
• Leave the other issues of optional matches for further discussions and fixes.

Special notes for your reviewer, ex. impact of this fix, design document, etc:

• Needs to check whether this would cause other problems.
• There are other known problems with optional match, which are left out of this PR.

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• TCK

Affects:

• [] Documentation affected (Please add the label if documentation needs to be modified.)
• [] Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

Please confirm whether to be reflected in release notes and how to describe:

ex. Fixed the bug .....

[xtcyclist]

After discussion, I close this PR because it only stops a singular optional match producing random wrong results without completely fixing all problems around optional match. So it comes with a risk of sabotaging other queries, many of which may not have been covered by our current tcks.

We need to discuss a PR to fully address all issues around optional match.