[IMPALA-3744] Pattern making in "show ... like ..." behaves differently from Hive

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: Impala 2.6.0
• Component/s: Frontend
• Labels: incompatibility newbie
• Assignee: Unassigned
• Reporter: Huaisi Xu
• Created: 14/Jun/16 20:38
• Updated: 19/Jun/20 19:02

Description

In impala:

[localhost:21000] > show tables;
Query: show tables
+------+
| name |
+------+
| a    |
| aa   |
| aaa  |
+------+
Fetched 3 row(s) in 0.01s
[localhost:21000] > show tables like "a";
Query: show tables like "a"
+------+
| name |
+------+
| a    |
+------+
Fetched 1 row(s) in 0.01s
[localhost:21000] > show tables like "a_";
Query: show tables like "a_"

Fetched 0 row(s) in 0.01s
[localhost:21000] > show tables like "a%";                                                                                                                                                                                                                                                 
Query: show tables like "a%"

Fetched 0 row(s) in 0.00s
[localhost:21000] > show tables like "a.";                                                                                                                                                                                                                                                 
Query: show tables like "a."

Fetched 0 row(s) in 0.00s
[localhost:21000] > show tables like "a*";
Query: show tables like "a*"
+------+
| name |
+------+
| a    |
| aa   |
| aaa  |
+------+
Fetched 3 row(s) in 0.01s

In Hive:

hive> show tables;
OK
a
aa
aaa
Time taken: 0.013 seconds, Fetched: 3 row(s)
hive> show tables like "a";
OK
a
Time taken: 0.012 seconds, Fetched: 1 row(s)
hive> show tables like "a_";
OK
aa
Time taken: 0.014 seconds, Fetched: 1 row(s)
hive> show tables like "a%";
OK
a
aa
aaa
Time taken: 0.014 seconds, Fetched: 3 row(s)
hive> show tables like "a.";
OK
aa
Time taken: 0.011 seconds, Fetched: 1 row(s)
hive> show tables like "a*";
OK
a
aa
aaa
Time taken: 0.015 seconds, Fetched: 3 row(s)

The problem seems to be http://github.mtv.cloudera.com/CDH/Impala/blob/cdh5-trunk/fe/src/main/java/com/cloudera/impala/util/PatternMatcher.java

It is very confusing to have two pattern matcher.. we use Hive pattern matcher in this case, but it escapes ".", which is a bit surprising.

Solution is to only use JdbcPatternMatcher, but this may break our API.