Postgres: Correct parsing of multiline statements

[tyrannosaurus-becks]

Fixes #6098

Postgres was splitting statements on a semicolon. This would be fine normally, but sometimes people do send statements with semicolons that need to be parsed as a single query.

Example:

// User sends:
DO $$ BEGIN IF NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname='my_role') THEN CREATE ROLE my_role; END IF; END $$

// In the current state, Postgres executes the first piece as an independent piece
// causing a syntax error: 
DO $$ BEGIN IF NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname='my_role') THEN CREATE ROLE my_role

// After this PR, it will be sent as the original syntax:
DO $$ BEGIN IF NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname='my_role') THEN CREATE ROLE my_role; END IF; END $$

[ncabatoff]

I wonder if it would make more sense to define a multiline string as one starting with DO . That's AFAIK the only way to begin a multi-line statement. And although dollar quoting is recommended for the body of the anonymous DO function, it's not required, so in theory they could put a multi-line statement within single quotes I think.

[tyrannosaurus-becks]

Hi @ncabatoff ! Thanks for the review! :-)

Regarding this:

I wonder if it would make more sense to define a multiline string as one starting with DO . That's AFAIK the only way to begin a multi-line statement. And although dollar quoting is recommended for the body of the anonymous DO function, it's not required, so in theory they could put a multi-line statement within single quotes I think.

I did some poking around and it looks like it would be possible for multiline statements to not include DO.

[ncabatoff]

I did some poking around and it looks like it would be possible for multiline statements to not include DO.

Hmm, you're right. I was making the assumption that they wouldn't be issuing DDL statements because that would be weird, but people do weird stuff all the time...

[Legogris]

Looking in the changelog, it seems this has not been released yet? Was it simply omitted from the changelog or is it yet to be released?

(Encountering the same issue in 1.5.0)

[ncabatoff]

Looking in the changelog, it seems this has not been released yet? Was it simply omitted from the changelog or is it yet to be released?

(Encountering the same issue in 1.5.0)

Sorry, we missed adding it to the 1.5.0 changelog (I just added it there now.). Please open a new issue if you're still having problems of this sort with 1.5.0.