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expression: fix painc on substring_index #7806

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merged 8 commits into from
Oct 8, 2018
Merged

expression: fix painc on substring_index #7806

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14eb73f
expression: fix painc on substring_index
zz-jason Sep 28, 2018
7a2bba2
Merge branch 'master' into dev/fix-substr-index
zz-jason Sep 28, 2018
3390d2d
Merge branch 'master' into dev/fix-substr-index
zz-jason Oct 8, 2018
028df83
address comment
zz-jason Oct 8, 2018
e585207
Merge branch 'dev/fix-substr-index' of https://github.com/zz-jason/ti…
zz-jason Oct 8, 2018
6c8a611
address comment
zz-jason Oct 8, 2018
f706ceb
tiny refine
zz-jason Oct 8, 2018
cf78602
Merge branch 'master' into dev/fix-substr-index
eurekaka Oct 8, 2018
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3 changes: 3 additions & 0 deletions expression/builtin_string.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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. -(1<<63) is ok?
  2. Do we need to leave a comment here to explain this check?

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

if count < end {
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1 change: 1 addition & 0 deletions expression/integration_test.go
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Expand Up @@ -736,6 +736,7 @@ func (s *testIntegrationSuite) TestStringBuiltin(c *C) {
result.Check(testkit.Rows("www.pingcap 12345 45 2017 01:01"))
result = tk.MustQuery(`select substring_index('www.pingcap.com', '.', 0), substring_index('www.pingcap.com', '.', 100), substring_index('www.pingcap.com', '.', -100)`)
result.Check(testkit.Rows(" www.pingcap.com www.pingcap.com"))
tk.MustQuery(`select substring_index('xyz', 'abc', 9223372036854775808)`).Check(testkit.Rows(``))
result = tk.MustQuery(`select substring_index('www.pingcap.com', 'd', 1), substring_index('www.pingcap.com', '', 1), substring_index('', '.', 1)`)
result.Check(testutil.RowsWithSep(",", "www.pingcap.com,,"))
result = tk.MustQuery(`select substring_index(null, '.', 1), substring_index('www.pingcap.com', null, 1), substring_index('www.pingcap.com', '.', null)`)
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