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perf(query): use quickselect instead of sorting while pagination #8995

Merged
merged 13 commits into from
Sep 14, 2023
Merged

perf(query): use quickselect instead of sorting while pagination #8995

merged 13 commits into from
Sep 14, 2023

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harshil-goel
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@harshil-goel harshil-goel commented Sep 7, 2023 •
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When we get pagination request, we still sort the entire structure and then return relevant results. This diff introduces mini select algorithm that will only sort till we get first k elements out of n.

Both LDBC Benchmarks and MicroBenchmarks show that this is only useful until 50%

LDBC Queries Benchmarks
Total elements : 300000
Current main:
BenchmarkQueries/IC09/First_:20-8                      1        36621508916 ns/op
BenchmarkQueries/IC09/First_:304368-8                  1        50905281926 ns/op
BenchmarkQueries/IC09/First_:608716-8                  1        63878833326 ns/op
BenchmarkQueries/IC09/First_:913064-8                  1        77455114015 ns/op
BenchmarkQueries/IC09/First_:1217412-8                 1        94143638593 ns/op
BenchmarkQueries/IC09/First_:1521760-8                 1        111483390712 ns/op
BenchmarkQueries/IC09/First_:1826108-8                 1        123910498449 ns/op


QuickSelect:
BenchmarkQueries/IC09/First_:20-8                      1        32248068234 ns/op
BenchmarkQueries/IC09/First_:304368-8                  1        45877353021 ns/op
BenchmarkQueries/IC09/First_:608716-8                  1        60671818631 ns/op
BenchmarkQueries/IC09/First_:913064-8                  1        73447308743 ns/op
BenchmarkQueries/IC09/First_:1217412-8                 1        90371662972 ns/op
BenchmarkQueries/IC09/First_:1521760-8                 1        112880718231 ns/op
BenchmarkQueries/IC09/First_:1826108-8                 1        125487157700 ns/op

In microbenchmarks, first row is the current sort. Further rows are various different k values for the new algo

MicroBenchmarks
Normal Sort vs QuickSelect
BenchmarkSortQuickSort/Normal_Sort_Ratio_1000000_-8                    1        1652489894 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_1-8                1          77946322 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_166667-8                   1         327467804 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_333333-8                   1         613629295 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_499999-8                   1         899239726 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_666665-8                   1        1231191998 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_833331-8                   1        1565101591 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_999997-8                   1        1746166978 ns/op

@dgraph-bot dgraph-bot added area/core internal mechanisms go Pull requests that update Go code labels Sep 7, 2023
mangalaman93
mangalaman93 requested changes Sep 8, 2023
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  1. we don't need to compare start == 0
  2. what if end is close to len(ul.Uids)

mangalaman93
mangalaman93 requested changes Sep 10, 2023
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  1. move the quick select code to another files in the types package
  2. Fix the benchmarks
  3. Add a TODO in line 458 of worker/sort.go
  4. Update the description with the new benchmarks
  5. Add a reference to the place where we copied the quicksort code

@mangalaman93 mangalaman93 changed the title Update sorting function to improve performance perf(query): use quickselect instead of sorting while pagination Sep 14, 2023
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LG, minor comments

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jairad26
jairad26 previously approved these changes Sep 14, 2023
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lgtm

jairad26
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lgtm

@mangalaman93 mangalaman93 merged commit 8d744e6 into main Sep 14, 2023
@mangalaman93 mangalaman93 deleted the harshil-goel/sort-fix branch September 14, 2023 20:58
shivaji-kharse pushed a commit that referenced this pull request Mar 12, 2024
@harshil-goel @mangalaman93
perf(query): use quickselect instead of sorting while pagination (#8995)
6357cb4 
When we get pagination request, we still sort the entire structure and
then return relevant results. This diff introduces mini select algorithm
that will only sort till we get first k elements out of n.

Both LDBC Benchmarks and MicroBenchmarks show that this is only useful
until 50%

```
LDBC Queries Benchmarks
Total elements : 300000
Current main:
BenchmarkQueries/IC09/First_:20-8                      1        36621508916 ns/op
BenchmarkQueries/IC09/First_:304368-8                  1        50905281926 ns/op
BenchmarkQueries/IC09/First_:608716-8                  1        63878833326 ns/op
BenchmarkQueries/IC09/First_:913064-8                  1        77455114015 ns/op
BenchmarkQueries/IC09/First_:1217412-8                 1        94143638593 ns/op
BenchmarkQueries/IC09/First_:1521760-8                 1        111483390712 ns/op
BenchmarkQueries/IC09/First_:1826108-8                 1        123910498449 ns/op
```

```
QuickSelect:
BenchmarkQueries/IC09/First_:20-8                      1        32248068234 ns/op
BenchmarkQueries/IC09/First_:304368-8                  1        45877353021 ns/op
BenchmarkQueries/IC09/First_:608716-8                  1        60671818631 ns/op
BenchmarkQueries/IC09/First_:913064-8                  1        73447308743 ns/op
BenchmarkQueries/IC09/First_:1217412-8                 1        90371662972 ns/op
BenchmarkQueries/IC09/First_:1521760-8                 1        112880718231 ns/op
BenchmarkQueries/IC09/First_:1826108-8                 1        125487157700 ns/op
```

In microbenchmarks, first row is the current sort. Further rows are
various different k values for the new algo

```
MicroBenchmarks
Normal Sort vs QuickSelect
BenchmarkSortQuickSort/Normal_Sort_Ratio_1000000_-8                    1        1652489894 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_1-8                1          77946322 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_166667-8                   1         327467804 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_333333-8                   1         613629295 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_499999-8                   1         899239726 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_666665-8                   1        1231191998 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_833331-8                   1        1565101591 ns/op
BenchmarkSortQuickSort/QuickSort_Sort_Ratio_1000000_999997-8                   1        1746166978 ns/op
```
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@jairad26 jairad26 jairad26 approved these changes

@mangalaman93 mangalaman93 mangalaman93 approved these changes

@meghalims meghalims Awaiting requested review from meghalims

@sanjayk-github-dev sanjayk-github-dev Awaiting requested review from sanjayk-github-dev

@all-seeing-code all-seeing-code Awaiting requested review from all-seeing-code

@billprovince billprovince Awaiting requested review from billprovince

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