BUG #14512: Backslashes in LIKE

The following bug has been logged on the website:

Bug reference: 14512
Logged by: Vojtěch Rylko
Email address: vojta(dot)rylko(at)gmail(dot)com
PostgreSQL version: 9.5.5
Operating system: Linux 3.19.0-32-generic x86_64
Description:

Hi, LIKE behaves differently depending on left side.

> select 1 where '\' like '\\\'; -- one and three backslashes
?column?
----------
(0 rows)

> select 1 where '\\' like '\\\'; -- two and three backslashes
ERROR: LIKE pattern must not end with escape character

The same behaviour occurs also with usage of table:

root=# create table t (a varchar);
CREATE TABLE
root=# insert into t values ('\'); -- one backslash
INSERT 0 1
root=# select * from t where t.a like '\\\'; -- three backslashes
a
---
(0 rows)

root=# insert into t values ('\\'); -- two backslashes
INSERT 0 1
root=# select * from t where t.a like '\\\'; -- three backslashes
ERROR: LIKE pattern must not end with escape character

Cheers,
Vojta Rylko, vry.cz