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GH-3263: Add DictionaryPage.decode to allow dictionary reuse in the ColumnReaderBase ctor #3264

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Merged
wgtmac merged 7 commits into from
Aug 15, 2025
Merged

GH-3263: Add DictionaryPage.decode to allow dictionary reuse in the ColumnReaderBase ctor #3264

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7ac4953
Add c-tor to ColumnReaderBase to allow dictionary reuse
pyckle Aug 6, 2025
73f68c7
add getDictionary function to PageReader
pyckle Aug 7, 2025
a9f07e1
run spotless
pyckle Aug 7, 2025
a220df6
add converter logic mistakenly removed
pyckle Aug 7, 2025
e6930f9
move getDictionary to DictionaryPage
pyckle Aug 10, 2025
a69918a
improve naming
Aug 11, 2025
69b45e2
test that getting a dict from decode rather than decoding bytes works
Aug 14, 2025
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14 changes: 3 additions & 11 deletions parquet-column/src/main/java/org/apache/parquet/column/impl/ColumnReaderBase.java
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Original file line number Diff line number Diff line change
Expand Up @@ -453,17 +453,9 @@ void writeValue() {
this.writerVersion = writerVersion;
this.maxDefinitionLevel = path.getMaxDefinitionLevel();
DictionaryPage dictionaryPage = pageReader.readDictionaryPage();
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if (dictionaryPage != null) {
try {
this.dictionary = dictionaryPage.getEncoding().initDictionary(path, dictionaryPage);
if (converter.hasDictionarySupport()) {
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converter.setDictionary(dictionary);
}
} catch (IOException e) {
throw new ParquetDecodingException("could not decode the dictionary for " + path, e);
}
} else {
this.dictionary = null;
this.dictionary = dictionaryPage == null ? null : dictionaryPage.getDictionary(path);
if (dictionary != null && converter.hasDictionarySupport()) {
converter.setDictionary(dictionary);
}
this.totalValueCount = pageReader.getTotalValueCount();
if (totalValueCount <= 0) {
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14 changes: 14 additions & 0 deletions parquet-column/src/main/java/org/apache/parquet/column/page/DictionaryPage.java
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Expand Up @@ -21,7 +21,10 @@
import java.io.IOException;
import java.util.Objects;
import org.apache.parquet.bytes.BytesInput;
import org.apache.parquet.column.ColumnDescriptor;
import org.apache.parquet.column.Dictionary;
import org.apache.parquet.column.Encoding;
import org.apache.parquet.io.ParquetDecodingException;

/**
* Data for a dictionary page
Expand Down Expand Up @@ -74,6 +77,17 @@ public DictionaryPage copy() throws IOException {
return new DictionaryPage(BytesInput.copy(bytes), getUncompressedSize(), dictionarySize, encoding);
}

/**
* @return the decoded dictionary
*/
public Dictionary getDictionary(ColumnDescriptor path) {
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try {
return getEncoding().initDictionary(path, this);
} catch (IOException e) {
throw new ParquetDecodingException("could not decode the dictionary for " + path, e);
}
}

@Override
public String toString() {
return "Page [bytes.size=" + bytes.size() + ", entryCount=" + dictionarySize + ", uncompressedSize="
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