expression: fix painc on substring_index #7806
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eurekaka
reviewed
Sep 28, 2018
| @@ -1208,6 +1208,9 @@ func (b *builtinSubstringIndexSig) evalString(row chunk.Row) (d string, isNull b | |||
| end = count | |||
| } | |||
| } else { | |||
| if count <= -int64(math.Pow(2, 63)) { | |||
| return "", false, nil | |||
| } | |||
| // If count is negative, everything to the right of the final delimiter (counting from the right) is returned. | |||
| count = -count | |||
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can we just check count < 0 again here?
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I think we don't need to check count<0 again. Because once we enter the above else branch, count<0 is guaranteed.
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the else branch indicates the count is < 0, then we assign -count to count, I mean, if we check count < 0 again after assigning -count to count, we can remove if count <= -int64(math.Pow(2, 63)) check then.
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Got it. Comment addressed, PTAL again
XuHuaiyu
reviewed
Oct 8, 2018
expression/builtin_string.go
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| @@ -1208,6 +1208,9 @@ func (b *builtinSubstringIndexSig) evalString(row chunk.Row) (d string, isNull b | |||
| end = count | |||
| } | |||
| } else { | |||
| if count <= -int64(math.Pow(2, 63)) { | |||
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- -(1<<63) is ok?
- Do we need to leave a comment here to explain this check?
XuHuaiyu
approved these changes
Oct 8, 2018
|
/run-all-tests |
|
/run-common-test tidb-test=pr/631 |
|
/run-integration-common-test tidb-test=pr/631 |
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What problem does this PR solve?
This PR fixes the panic in
substring_index:What is changed and how it works?
Check List
Tests