Impala sorting Issue

String sorting of impala is inconsistent with our expectations:

Impala sorting
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SELECT BQT1.SmallA.StringNum FROM BQT1.SmallA

Results
1: -1
2: -10
3: -11
4: -12
5: -13
6: -14
7: -15
8: -16
9: -17
10: -18
11: -19
12: -2
13: -20
14: -21
15: -22
16: -24
17: -3
18: -4
19: -5
20: -6
21: -8
22: -9
23: 0
24: 1
25: 10
26: 11
27: 12
28: 13
29: 14
30: 15
31: 16
32: 17
33: 18
34: 19
35: 2
36: 20
37: 21
38: 22
39: 23
40: 24
41: 3
42: 4
43: 5
44: 6
45: 7
46: 8
47: null
48: null
49: null
50: null

Expected
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While we expect sorting to be consistent with other sources:

1: 0
2: 1
3: -1
4: 10
5: -10
6: 11
7: -11
8: 12
9: -12
10: 13
11: -13
12: 14
13: -14
14: 15
15: -15
16: 16
17: -16
18: 17
19: -17
20: 18
21: -18
22: 19
23: -19
24: 2
25: -2
26: 20
27: -20
28: 21
29: -21
30: 22
31: -22
32: 23
33: 24
34: -24
35: 3
36: -3
37: 4
38: -4
39: 5
40: -5
41: 6
42: -6
43: 7
44: 8
45: -8
46: -9
47: null
48: null
49: null
50: null