CREATE OR REPLACE FUNCTION

[xzdandy]

• Support from parser to executor.
• Fix existing unit tests and short integration tests.
• Add unit tests for CREATE OR REPALCE FUNCTION
• Update documentation
• Add integration test
• Check no long integration test failed due to this PR

Close #1131

[jiashenC]

What will be the bahavior of CREATE OR REPLACE FUNCTION ... IF NOT EXISTS ...?

It seems like Postgres (https://www.postgresql.org/docs/current/sql-createfunction.html) only allows CREATE OR REPLACE but not IF NOT EXISTS for FUNCTION.

[xzdandy]

What will be the bahavior of CREATE OR REPLACE FUNCTION ... IF NOT EXISTS ...?

It seems like Postgres (https://www.postgresql.org/docs/current/sql-createfunction.html) only allows CREATE OR REPLACE but not IF NOT EXISTS for FUNCTION.

What will be the bahavior of CREATE OR REPLACE FUNCTION ... IF NOT EXISTS ...?

It seems like Postgres (https://www.postgresql.org/docs/current/sql-createfunction.html) only allows CREATE OR REPLACE but not IF NOT EXISTS for FUNCTION.

Yes, Postgres only supports ‘OR REPLACE’. I think it does not hurt support both, so did not remove the ‘IF NOT EXISTS’ support. When both are specified, an error message is raised.