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Code Block
long totalStartTime = System.nanoTime();
    for (int fileIndex = 0; fileIndex < fileNum; fileIndex++) {
      // file path
      String path =
          "/home/fit/szs/data/data/sequence/root.sg/0/"
              + chunkNum
              + "/test"
              + fileIndex
              + ".tsfile";

      // aggregation query
      try (TsFileSequenceReader reader = new TsFileSequenceReader(path)) {
        Path seriesPath = new Path(DEVICE1, "sensor_1");
        long startTime = System.nanoTime();
        TimeseriesMetadata timeseriesMetadata = reader.readTimeseriesMetadata(seriesPath, false);
        long count = timeseriesMetadata.getStatistics().getCount();
        costTime += (System.nanoTime() - startTime);
      }
    }
    System.out.println(
        "Total raw read cost time: " + (System.nanoTime() - totalStartTime) / 1000_000 + "ms");
    System.out.println("Index area cost time: " + costTime / 1000_000 + "ms");



chunk number


1

2

3

5

8

10

15

20

25

raw

with timeseriesMetadata

overall cost time (ms)

210

230

237

250

276

297

309

344

374

index area time (ms)

116

131

142

156

185

197

220

255

282

without timeseriesMetadata

overall cost time (ms)


219

223

242

267

287

302

334

357

index area time (ms)


131

136

155

182

200

219

251

274

count(*)

with timeseriesMetadata

overall cost time (ms)

89

90

91

93

93

93

94

97

97

index area time (ms)

15

16

16

16

16

16

16

17

17

without timeseriesMetadata

overall cost time (ms)


122

123

127

127

127

127

128

130

index area time (ms)


50

50

50

50

51

52

52

53


Image Modified

Conclusion:

  1. Although the index area structure with no TimeseriesMetadata speeds up a little (about 5%) in raw data query,
    it reduces the speed a lot in aggregation query (about 30%). => We should reserve TimeseriesMetadata.
  2. The time cost does not change in the data area of TsFile.


(II) Experiment about combine Chunk and Page

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