Expression Implementation

[dkhenry]

Feature Description

Implement the expression logic needed to match the MySQL Expression Engine. The following are expressions that need to be supported

• Addition 1 + 1
• Subtraction 1 - 1
• Multiplication 1 * 1
• Division 1 / 1

Long term the full list of expressions to handle can be found here https://dev.mysql.com/doc/refman/5.6/en/non-typed-operators.html

Use Case(s)

Queries that must evaluate these expressions

[systay]

Do you have an example query that could benefit from implementing this? When do we try to execute this instead of passing it down to the actual MySQL engine?

[sougou]

There are a few in https://github.com/vitessio/vitess/blob/master/go/vt/vtgate/planbuilder/testdata/unsupported_cases.txt. For example:

# expression on a cross-shard subquery
"select id+1 from (select user.id, user.col from user join user_extra) as t"
"unsupported: expression on results of a cross-shard subquery"

[deepthi]

Re-opening since multiplication and division are not yet complete.

[harshit-gangal]

@deepthi I see the support is added now.

[deepthi]

@deepthi I see the support is added now.

🎉