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aggfuncs: implement bit-or with new aggregation framework #6975

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merged 9 commits into from
Jul 5, 2018
Merged

aggfuncs: implement bit-or with new aggregation framework #6975

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6b7ecfe
aggfuncs: implement bit-or
crazycs520 Jul 4, 2018
ced83db
aggfuncs: rename variable name
crazycs520 Jul 4, 2018
5f59da3
aggfuncs: add comment
crazycs520 Jul 4, 2018
742a5ff
aggfuncs: bit_or refactor
crazycs520 Jul 4, 2018
da9bfd1
Merge branch 'master' of https://github.com/pingcap/tidb into dev/agg…
crazycs520 Jul 5, 2018
d826d6b
aggfuncs: bit_or add only handle uint64 judge
crazycs520 Jul 5, 2018
0b00dc8
aggfuncs: rename func_bit_or.go to func_bitfunc.go
crazycs520 Jul 5, 2018
836aafd
aggfuncs: refactor bit or functions
crazycs520 Jul 5, 2018
cd51cdb
Merge branch 'master' into dev/agg-bit-or
XuHuaiyu Jul 5, 2018
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12 changes: 7 additions & 5 deletions executor/aggfuncs/aggfuncs.go
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Expand Up @@ -32,11 +32,13 @@ var (
_ AggFunc = (*avgOriginal4Float64)(nil)
_ AggFunc = (*avgPartial4Float64)(nil)

// All the AggFunc implementations for "FIRSTROW" are listed here.
// All the AggFunc implementations for "MAX" are listed here.
// All the AggFunc implementations for "MIN" are listed here.
// All the AggFunc implementations for "GROUP_CONCAT" are listed here.
// All the AggFunc implementations for "BIT_OR" are listed here.
// All the AggFunc implementations for "FIRSTROW" are listed here.
// All the AggFunc implementations for "MAX" are listed here.
// All the AggFunc implementations for "MIN" are listed here.
// All the AggFunc implementations for "GROUP_CONCAT" are listed here.
// All the AggFunc implementations for "BIT_OR" are listed here.
_ AggFunc = (*bitOrUint64)(nil)

// All the AggFunc implementations for "BIT_XOR" are listed here.
// All the AggFunc implementations for "BIT_AND" are listed here.
)
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7 changes: 6 additions & 1 deletion executor/aggfuncs/builder.go
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Expand Up @@ -120,7 +120,12 @@ func buildGroupConcat(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc

// buildCount builds the AggFunc implementation for function "BIT_OR".
func buildBitOr(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
return nil
// BIT_OR doesn't need to handle the distinct property.
base := baseAggFunc{
args: aggFuncDesc.Args,
ordinal: ordinal,
}
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need to handle the function which has the distinct property.

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why bit-or need to care distinct property?

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consider this query: select bit_or(distinct a) from t; we only calculate the distinct values of column a in this kind of query.

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It doesn't matter, because bit_or(distinct a) = bit_or(a), bit_and same too, except bit_xor.

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ok

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please add a comment here to statement that function bitor no need to consider the distinct property

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done

return &bitOrUint64{baseBitAggFunc{base}}
}

// buildCount builds the AggFunc implementation for function "BIT_XOR".
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60 changes: 60 additions & 0 deletions executor/aggfuncs/func_bit_or.go
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@@ -0,0 +1,60 @@
// Copyright 2018 PingCAP, Inc.
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rename the filename as func_bitfuncs.go

//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package aggfuncs

import (
"github.com/juju/errors"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/util/chunk"
)

type baseBitAggFunc struct {
baseAggFunc
}

type bitOrUint64 struct {
baseBitAggFunc
}

type partialResult4BitFunc = uint64

func (e *bitOrUint64) AllocPartialResult() PartialResult {
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This can be a member function of *baseBitAggFunc.

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great suggestion.

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...I take back the last sentence. 😂
We should not make the result value to be a member of baseBitAggFunc , Because this will make The baseBitAggFunc to be Stateful.
Consider another scenario, If we have many groups to be aggregated, if the AggFunc is statefull, we have to create many aggFunc to handle this.
But if AggFunc is not statefull, we can only create one AggFunc and many partialResult4BitFunc, this will reduce go GC pressure.
( This is @zz-jason told me. Thanks very much~ )

return PartialResult(new(partialResult4BitFunc))
}

func (e *bitOrUint64) ResetPartialResult(pr PartialResult) {
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ditto

p := (*partialResult4BitFunc)(pr)
*p = 0
}

func (e *bitOrUint64) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
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ditto

p := (*partialResult4BitFunc)(pr)
chk.AppendUint64(e.ordinal, *p)
return nil
}

func (e *bitOrUint64) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error {
p := (*partialResult4BitFunc)(pr)
for _, row := range rowsInGroup {
inputValue, isNull, err := e.args[0].EvalInt(sctx, row)
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Should we wrap a cast as uint in typeInfer4BitFuncs,
or bit_or(varchar) may fail?

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bit_or( varchar ) will return 0.

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actually, we need to add a cast, consider this case:

drop table if exists t;
create table t(a decimal(10, 4));
insert into t values(12.2);
select bit_or(a) from (select * from t union all select * from t) tmp;
TiDB(localhost:4000) > desc select bit_or(a) from (select * from t union all select * from t) tmp;
+--------------------------+------+----------------------------------------------+----------+
| id                       | task | operator info                                | count    |
+--------------------------+------+----------------------------------------------+----------+
| StreamAgg_13             | root | funcs:bit_or(tmp.a)                          | 1.00     |
| └─Union_21               | root |                                              | 20000.00 |
|   ├─TableReader_24       | root | data:TableScan_23                            | 10000.00 |
|   │ └─TableScan_23       | cop  | table:t, range:[-inf,+inf], keep order:false | 10000.00 |
|   └─TableReader_27       | root | data:TableScan_26                            | 10000.00 |
|     └─TableScan_26       | cop  | table:t, range:[-inf,+inf], keep order:false | 10000.00 |
+--------------------------+------+----------------------------------------------+----------+
6 rows in set (0.00 sec)

The above StreamAgg_13 directly handles the original data instead of another aggregate operator's partial result, which is guaranteed to be uint64. This PR may failed on this query if we don't wrap a cast on it's parameter.

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Ye, I'll fix it

if err != nil {
return errors.Trace(err)
}
if isNull {
continue
}
*p |= uint64(inputValue)
}
return nil
}