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Order index segments in multi segments builder in descending order. (#…
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notbdu authored Nov 13, 2020
1 parent 07d0997 commit dd58747
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6 changes: 6 additions & 0 deletions src/m3ninx/index/segment/builder/multi_segments_builder.go
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Expand Up @@ -138,6 +138,12 @@ func (b *builderFromSegments) AddSegments(segments []segment.Segment) error {
b.segmentsOffset += postings.ID(added)
}

// Sort segments in descending order in terms of size so the multi segments
// terms iter more efficiently builds its postings list.
sort.Slice(b.segments, func(i, j int) bool {
return b.segments[i].segment.Size() > b.segments[j].segment.Size()
})

// Make sure the terms iter has all the segments to combine data from
b.termsIter.reset(b.segments)

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79 changes: 79 additions & 0 deletions src/m3ninx/index/segment/builder/multi_segments_builder_test.go
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@@ -0,0 +1,79 @@
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package builder

import (
"sort"
"testing"

"github.com/golang/mock/gomock"
"github.com/stretchr/testify/require"

"github.com/m3db/m3/src/m3ninx/index"
"github.com/m3db/m3/src/m3ninx/index/segment"
"github.com/m3db/m3/src/m3ninx/postings"
)

// TestMultiSegmentsBuilderSortedBySizeDescending ensures that segments in the
// multi segments builder are in descending order by size for optimal compaction.
func TestMultiSegmentsBuilderSortedBySizeDescending(t *testing.T) {
ctrl := gomock.NewController(t)
defer ctrl.Finish()

b := NewBuilderFromSegments(NewOptions()).(*builderFromSegments)

numSegments := 5
segs := make([]segment.Segment, 0, numSegments)
for i := 1; i <= numSegments; i++ {
pi := postings.NewMockIterator(ctrl)
gomock.InOrder(
pi.EXPECT().Next().Return(false),
pi.EXPECT().Close().Return(nil),
)
r := segment.NewMockReader(ctrl)
it := index.NewIDDocIterator(nil, pi)
gomock.InOrder(
r.EXPECT().AllDocs().Return(it, nil),
r.EXPECT().Close().Return(nil),
)

seg := segment.NewMockSegment(ctrl)
seg.EXPECT().Reader().Return(r, nil)
seg.EXPECT().Size().Return(int64(i * 10)).AnyTimes()
seg.EXPECT().TermsIterable().Return(nil)
segs = append(segs, seg)
}
require.NoError(t, b.AddSegments(segs))

// Sort segments in descending order by size.
sort.Slice(segs, func(i, j int) bool {
return segs[i].Size() > segs[j].Size()
})

actualSegs := make([]segment.Segment, 0, numSegments)
for _, segMD := range b.segments {
actualSegs = append(actualSegs, segMD.segment)
}

for i := 0; i < numSegments; i++ {
require.Equal(t, segs[i].Size(), actualSegs[i].Size())
}
}

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