Use 8byte offsets in chunk based raw index creator #5285
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| Original file line number | Diff line number | Diff line change |
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@@ -49,7 +49,7 @@ | |
| */ | ||
| @NotThreadSafe | ||
| public class VarByteChunkSingleValueWriter extends BaseChunkSingleValueWriter { | ||
| private static final int CURRENT_VERSION = 3; | ||
| public static final int CHUNK_HEADER_ENTRY_ROW_OFFSET_SIZE = Integer.BYTES; | ||
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| private final int _chunkHeaderSize; | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -43,7 +43,7 @@ static PinotNativeOrderLBuffer loadFile(File file, long offset, long size) | |
| return buffer; | ||
| } | ||
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| public static PinotNativeOrderLBuffer mapFile(File file, boolean readOnly, long offset, long size) | ||
| throws IOException { | ||
| if (readOnly) { | ||
| return new PinotNativeOrderLBuffer(new MMapBuffer(file, offset, size, MMapMode.READ_ONLY), true, false); | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -43,7 +43,7 @@ static PinotNonNativeOrderLBuffer loadFile(File file, long offset, long size) | |
| return buffer; | ||
| } | ||
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| public static PinotNonNativeOrderLBuffer mapFile(File file, boolean readOnly, long offset, long size) | ||
| throws IOException { | ||
| if (readOnly) { | ||
| return new PinotNonNativeOrderLBuffer(new MMapBuffer(file, offset, size, MMapMode.READ_ONLY), true, false); | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -21,16 +21,20 @@ | |
| import java.io.File; | ||
| import java.io.IOException; | ||
| import java.net.URL; | ||
| import java.nio.ByteOrder; | ||
| import java.nio.charset.Charset; | ||
| import java.util.Random; | ||
| import org.apache.commons.io.FileUtils; | ||
| import org.apache.commons.lang.RandomStringUtils; | ||
| import org.apache.pinot.common.utils.StringUtil; | ||
| import org.apache.pinot.core.io.compression.ChunkCompressorFactory; | ||
| import org.apache.pinot.core.io.reader.impl.ChunkReaderContext; | ||
| import org.apache.pinot.core.io.reader.impl.v1.VarByteChunkSingleValueReader; | ||
| import org.apache.pinot.core.io.writer.impl.v1.VarByteChunkSingleValueWriter; | ||
| import org.apache.pinot.core.segment.creator.impl.fwd.SingleValueVarByteRawIndexCreator; | ||
| import org.apache.pinot.core.segment.memory.PinotDataBuffer; | ||
| import org.apache.pinot.core.segment.memory.PinotNativeOrderLBuffer; | ||
| import org.apache.pinot.core.segment.memory.PinotNonNativeOrderLBuffer; | ||
| import org.testng.Assert; | ||
| import org.testng.annotations.Test; | ||
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@@ -113,27 +117,37 @@ public void test(ChunkCompressorFactory.CompressionType compressionType) | |
| * @throws IOException | ||
| */ | ||
| @Test | ||
| public void testBackwardCompatibilityV1() | ||
| throws Exception { | ||
| String[] expected = new String[]{"abcde", "fgh", "ijklmn", "12345"}; | ||
| testBackwardCompatibilityHelper("data/varByteStrings.v1", expected, 1009); | ||
| } | ||
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| /** | ||
| * This test ensures that the reader can read in an data file from version 2. | ||
| */ | ||
| @Test | ||
| public void testBackwardCompatibilityV2() | ||
| throws Exception { | ||
| String[] data = {"abcdefghijk", "12456887", "pqrstuv", "500"}; | ||
| testBackwardCompatibilityHelper("data/varByteStringsCompressed.v2", data, 1000); | ||
|
There was a problem hiding this comment. Nice. Do we also want to add a v1 raw data in the tests? |
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| testBackwardCompatibilityHelper("data/varByteStringsRaw.v2", data, 1000); | ||
| } | ||
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| private void testBackwardCompatibilityHelper(String fileName, String[] data, int numDocs) | ||
| throws Exception { | ||
| ClassLoader classLoader = getClass().getClassLoader(); | ||
| URL resource = classLoader.getResource(fileName); | ||
| if (resource == null) { | ||
| throw new RuntimeException("Input file not found: " + fileName); | ||
| } | ||
| File file = new File(resource.getFile()); | ||
| try (VarByteChunkSingleValueReader reader = new VarByteChunkSingleValueReader( | ||
| PinotDataBuffer.mapReadOnlyBigEndianFile(file))) { | ||
| ChunkReaderContext context = reader.createContext(); | ||
| for (int i = 0; i < numDocs; i++) { | ||
| String actual = reader.getString(i, context); | ||
| Assert.assertEquals(actual, data[i % data.length]); | ||
| } | ||
| } | ||
| } | ||
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@@ -173,7 +187,7 @@ private void testLargeVarcharHelper(ChunkCompressorFactory.CompressionType compr | |
| int maxStringLengthInBytes = 0; | ||
| for (int i = 0; i < numDocs; i++) { | ||
| expected[i] = RandomStringUtils.random(random.nextInt(numChars)); | ||
| maxStringLengthInBytes = Math.max(maxStringLengthInBytes, StringUtil.encodeUtf8(expected[i]).length); | ||
| } | ||
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| int numDocsPerChunk = SingleValueVarByteRawIndexCreator.getNumDocsPerChunk(maxStringLengthInBytes); | ||
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@@ -183,20 +197,44 @@ private void testLargeVarcharHelper(ChunkCompressorFactory.CompressionType compr | |
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| for (int i = 0; i < numDocs; i += 2) { | ||
| writer.setString(i, expected[i]); | ||
| writer.setBytes(i + 1, StringUtil.encodeUtf8(expected[i])); | ||
| } | ||
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| writer.close(); | ||
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| PinotDataBuffer buffer = PinotDataBuffer.mapReadOnlyBigEndianFile(outFile); | ||
| try (VarByteChunkSingleValueReader reader = new VarByteChunkSingleValueReader(buffer)) { | ||
| ChunkReaderContext context = reader.createContext(); | ||
| for (int i = 0; i < numDocs; i += 2) { | ||
| String actual = reader.getString(i, context); | ||
| Assert.assertEquals(actual, expected[i]); | ||
| byte[] expectedBytes = StringUtil.encodeUtf8(expected[i]); | ||
| Assert.assertEquals(StringUtil.encodeUtf8(actual), expectedBytes); | ||
| Assert.assertEquals(reader.getBytes(i + 1, context), expectedBytes); | ||
| } | ||
| } | ||
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| // For large variable width column values (where total size of data | ||
| // across all rows in the segment is > 2GB), LBuffer will be used for | ||
| // reading the fwd index. However, to test this scenario the unit test | ||
| // will take a long time to execute due to comparison | ||
| // (75000 characters in each row and 10000 rows will hit this scenario). | ||
| // So we specifically test for mapping the index file into a LBuffer | ||
| // to exercise the LBuffer code | ||
| if (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN) { | ||
| buffer = PinotNativeOrderLBuffer.mapFile(outFile, true, 0, outFile.length()); | ||
| } else { | ||
| buffer = PinotNonNativeOrderLBuffer.mapFile(outFile, true, 0, outFile.length()); | ||
| } | ||
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| try (VarByteChunkSingleValueReader reader = new VarByteChunkSingleValueReader(buffer)) { | ||
| ChunkReaderContext context = reader.createContext(); | ||
| for (int i = 0; i < numDocs; i += 2) { | ||
| String actual = reader.getString(i, context); | ||
| Assert.assertEquals(actual, expected[i]); | ||
| byte[] expectedBytes = StringUtil.encodeUtf8(expected[i]); | ||
| Assert.assertEquals(StringUtil.encodeUtf8(actual), expectedBytes); | ||
| Assert.assertEquals(reader.getBytes(i + 1, context), expectedBytes); | ||
| } | ||
| } | ||
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nice.
I would also introduce a
private final _headerEntryChunkOffsetSizehere, and initialize it by calling a methodgetHeaderEntryChunkOffssetSize(version)in the writer.There was a problem hiding this comment.
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Done.
@mcvsubbu , this actually comes handy now itself since I haven't bumped the version of fixed byte chunk writer. It is still on version 2 and using 4-byte chunk offset entries in file header. So the current changes protect compatibility of v1/v2 for var-byte, read/write new var byte in v3 and still continue to read/write fixed byte indexes in v1/v2.
I am having mixed opinions on bumping up the version of fixed byte chunk writer to use 8byte offsets as well. The thing is that if we don't bump it up and tomorrow file format for fixed byte changes (for some reason), then we will bump it up to 3. At that time it will automatically get 8-byte offsets by virtue of being at version >=3. So may be do it now and keep the versions same.
The flip side is that you would ideally want to evolve fixed-byte and var-byte formats independently (which is what is done in this PR by keeping the fixed byte writer still at version 2). Obviously if we separate out base class and duplicate code, then things will be simplified but that's not the best option. Thoughts?
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Fixed and var byte formats cannot evolve independently unless we split the base class like you said. Some duplication can be avoided, but in the end, the version number at the top should decide what the format is, underneath.
I guess the con side of moving this for fixed byte will be that storage will (almost) double for the fixed byte no-dictionary columns?
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No my bad. It will be double offset per chunk, so it should be ok. Let us just make it 8 bytes for all like we discussed.
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Discussed offline. It is better to keep the version/format same so we will use 8-byte chunk offsets for fixed-byte indexes as well.
Storage overhead - Consider a segment with 10million rows. Since we currently pack 1000 rows in a fixed byte chunk, there will be 10k chunks. If the file header has 8-byte chunk offsets instead of 4, the storage overhead for the raw forward index of the particular column goes up by 40KB (10000 chunks * 4). Extrapolating this to 1000 segments on the server with roughly 5 fixed width no dictionary columns per segment, we are looking at 40KB * 1000 * 5 = 200MB
Will make the changes
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Made the changes as discussed