[IMPALA-6096] RLIKE/REGEXP operator and regexp_* functions require different character escaping

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: Impala 2.5.0
• Component/s: Frontend
• Epic Color: ghx-label-7
• Assignee: Unassigned
• Reporter: Harsh J
• Created: 20/Oct/17 21:23
• Updated: 13/Apr/18 15:47

Description

When escaping a regex-special character such as ( or [, the REGEXP/RLIKE operator requires a triple escape such as

\\\(

while the regexp_like/regexp_extract/etc. functions only require a double escape such as

\\(

Here's a test proving the difference in requirement:

CREATE TABLE test_regexp (a STRING);
INSERT INTO test_regexp VALUES ('This is a (string) with [special chars] that need e.s.c.a.p.i.n.g');

-- The below will fail
SELECT regexp_extract(a, 'This is a \\((.*)\\) with .*', 1) FROM test_regexp WHERE a RLIKE 'This is a \\(string.*';

-- The below will pass correctly
SELECT regexp_extract(a, 'This is a \\((.*)\\) with .*', 1) FROM test_regexp WHERE a RLIKE 'This is a \\\(string.*';

The failure message is:

invalid regular expression in 'a RLIKE 'This is a \\(string.*''

Could the escape format be unified between the two? Per the documentation, both are supposed to be following the standard RE2 syntax.

Issue Links

• relates to: IMPALA-2422 % escaping does not work correctly in a LIKE clause