Howto clean comments from raw sql file

Question

I have problem with cleaning comments and empty lines from already existing sql file. The file has over 10k lines so cleaning it manually is not an option.

I have a litt

Answer 1

Try the sqlparse module.

Updated example: leaving comments inside insert values, and comments within CREATE FUNCTION blocks. You can tweak further to tune the behavior:

import sqlparse
from sqlparse import tokens

queries = '''
CREATE FUNCTION func1(a integer) RETURNS void
    LANGUAGE plpgsql
        AS $$
        BEGIN
                -- comment
       END;
       $$;
SELECT -- comment
* FROM -- comment
TABLE foo;
-- comment
INSERT INTO foo VALUES ('a -- foo bar');
INSERT INTO foo
VALUES ('
a 
-- foo bar'
);

'''

IGNORE = set(['CREATE FUNCTION',])  # extend this

def _filter(stmt, allow=0):
    ddl = [t for t in stmt.tokens if t.ttype in (tokens.DDL, tokens.Keyword)]
    start = ' '.join(d.value for d in ddl[:2])
    if ddl and start in IGNORE:
        allow = 1
    for tok in stmt.tokens:
        if allow or not isinstance(tok, sqlparse.sql.Comment):
            yield tok

for stmt in sqlparse.split(queries):
    sql = sqlparse.parse(stmt)[0]
    print sqlparse.sql.TokenList([t for t in _filter(sql)])

Output:

CREATE FUNCTION func1(a integer) RETURNS void
    LANGUAGE plpgsql
        AS $$
        BEGIN
                -- comment
       END;
       $$;

SELECT * FROM TABLE foo;

INSERT INTO foo VALUES ('a -- foo bar');

INSERT INTO foo
VALUES ('
a
-- foo bar'
);