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planner: fix expression rewriter wrong compare logic #8269

Merged
merged 7 commits into from
Nov 13, 2018
Merged

planner: fix expression rewriter wrong compare logic #8269

merged 7 commits into from
Nov 13, 2018

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imtbkcat
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What problem does this PR solve?

#8248 has fixed compare logic for constant expression, but there is still error in following query:

CREATE TABLE t(a int, b int, c int);
INSERT INTO t VALUES (1, 2, 3), (NULL, 2, 3  ), 
(1, NULL, 3),(1, 2,   NULL),(NULL, 2, 3+1), (1, NULL, 3+1), 
(1, 2+1, NULL),(NULL, 2, 3-1), (1, NULL, 3-1), (1, 2-1, NULL);

TiDB:

mysql> SELECT * FROM t1 WHERE (a,b,c) >= (1,2,3);
+------+------+------+
| a    | b    | c    |
+------+------+------+
|    1 |    2 |    3 |
| NULL |    2 |    3 |
|    1 | NULL |    3 |
| NULL |    2 |    4 |
|    1 | NULL |    4 |
|    1 |    3 | NULL |
+------+------+------+
6 rows in set (0.00 sec)

MySQL:

mysql> SELECT * FROM t1 WHERE (a,b,c) >= (1,2,3);
+------+------+------+
| a    | b    | c    |
+------+------+------+
|    1 |    2 |    3 |
|    1 |    3 | NULL |
+------+------+------+
2 rows in set (0.00 sec)

What is changed and how it works?

Patch before just fixed bug when expression is constant expression, but ignore expression has variables. New patch changed expression rewrite logic.

Check List

Tests

  • Unit test

Code changes

  • Has exported variable/fields change

Side effects

  • Possible performance regression

Related changes

  • Need to cherry-pick to the release branch

@imtbkcat imtbkcat added type/bugfix This PR fixes a bug. sig/planner SIG: Planner labels Nov 12, 2018
XuHuaiyu
XuHuaiyu reviewed Nov 12, 2018
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go.mod Outdated Show resolved Hide resolved
planner/core/expression_rewriter.go
@@ -202,9 +202,10 @@ func (er *expressionRewriter) constructBinaryOpFunction(l expression.Expression,
return expression.ComposeCNFCondition(er.ctx, funcs...), nil
default:
larg0, rarg0 := expression.GetFuncArg(l, 0), expression.GetFuncArg(r, 0)
var expr1, expr2, expr3 expression.Expression
var expr1, expr2, expr3, expr4, expr5 expression.Expression
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Update the comments of this function.

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ok

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addressed

eurekaka
eurekaka reviewed Nov 12, 2018
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planner/core/expression_rewriter.go Outdated
// 2. Else constructBinaryOpFunctions converts (a0,a1,a2) op (b0,b1,b2) to
// `IF( (a0 NE b0) EQ 1, a0 op b0,
// IF ( (a0 NE b0) EQ Null, Null,
// IF ( (a0 NE b0) EQ 1, a1 op b1,
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s/a0 NE b0/a1 NE b1 ?

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ok

eurekaka
eurekaka reviewed Nov 12, 2018
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rest LGTM

@eurekaka eurekaka added the status/LGT1 Indicates that a PR has LGTM 1. label Nov 12, 2018
@imtbkcat
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/run-all-tests

winoros
winoros reviewed Nov 12, 2018
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planner/core/expression_rewriter.go Outdated
// a1 op b1,
// a2 op b2)
// )`
// IF ( (a0 NE b0) EQ Null, Null,
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One tab here may be better?

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ok

@imtbkcat
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/run-all-tests

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@imtbkcat
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/run-all-tests

@imtbkcat
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PTAL @XuHuaiyu @winoros

XuHuaiyu
XuHuaiyu reviewed Nov 12, 2018
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planner/core/expression_rewriter.go Outdated
// a1 op b1,
// a2 op b2)
// )`
// IF ( (a0 NE b0) EQ Null, Null,
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s/ (a0 NE b0) EQ Null/ IsNull(a0 NE b0)?
The result of (a0 NE b0) EQ Null will always be null

XuHuaiyu
XuHuaiyu reviewed Nov 12, 2018
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planner/core/expression_rewriter.go Outdated
// a2 op b2)
// )`
// IF ( (a0 NE b0) EQ Null, Null,
// IF ( a0 NE b0, a1 op b1,
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s/ a0 NE b0/ a1 NE b1 ?

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@XuHuaiyu addressed

@zz-jason
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LGTM

XuHuaiyu
XuHuaiyu approved these changes Nov 13, 2018
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LGTM

@XuHuaiyu
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Please cherry-pick this to release-2.1 and release-2.0. @imtbkcat

@zz-jason zz-jason added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Nov 13, 2018
@imtbkcat imtbkcat merged commit a28a3a7 into pingcap:master Nov 13, 2018
@imtbkcat imtbkcat mentioned this pull request Nov 13, 2018
Merged
jackysp pushed a commit that referenced this pull request Nov 13, 2018
@jackysp
planner: fix expression rewriter wrong compare logic (#8269) (#8288)
162fa84
@imtbkcat imtbkcat mentioned this pull request Nov 13, 2018
Merged
jackysp pushed a commit that referenced this pull request Nov 13, 2018
@jackysp
planner: fix expression rewriter wrong compare logic (#8269) (#8289)
67b37c5
@imtbkcat imtbkcat deleted the fixrewriter branch November 13, 2018 11:27
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@eurekaka eurekaka eurekaka left review comments

@winoros winoros winoros left review comments

@XuHuaiyu XuHuaiyu XuHuaiyu approved these changes

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@imtbkcat @zz-jason @XuHuaiyu @eurekaka @winoros