kazuyukitanimura commented on a change in pull request #34611:
URL: https://github.com/apache/spark/pull/34611#discussion_r754823543
##########
File path:
sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedPlainValuesReader.java
##########
@@ -53,19 +53,47 @@ public void skip() {
throw new UnsupportedOperationException();
}
+ private void updateCurrentByte() {
+ try {
+ currentByte = (byte) in.read();
+ } catch (IOException e) {
+ throw new ParquetDecodingException("Failed to read a byte", e);
+ }
+ }
+
@Override
public final void readBooleans(int total, WritableColumnVector c, int rowId)
{
- // TODO: properly vectorize this
- for (int i = 0; i < total; i++) {
- c.putBoolean(rowId + i, readBoolean());
+ int i = 0;
+ if (bitOffset > 0) {
+ i = Math.min(8 - bitOffset, total);
+ c.putBooleans(rowId, i, currentByte, bitOffset);
+ bitOffset = (bitOffset + i) & 7;
+ }
+ for (; i + 7 < total; i += 8) {
+ updateCurrentByte();
+ c.putBooleans(rowId + i, currentByte);
+ }
+ if (i < total) {
+ updateCurrentByte();
+ bitOffset = total - i;
+ c.putBooleans(rowId + i, bitOffset, currentByte, 0);
}
}
@Override
public final void skipBooleans(int total) {
- // TODO: properly vectorize this
- for (int i = 0; i < total; i++) {
- readBoolean();
+ // using >>3 instead of /8 below since Java division rounds towards zero
i.e. (-1)/8=0
Review comment:
Oh I see. The difference is important when `(total-(8-bitOffset))<0.`
E.g. `(-1)>>3=(-1)` vs. `(-1)/8=0`. The latter incorrectly enters the
`if(numBytesToSkip>=0){`. I updated the comment, hopefully it is clearer now.
We should not call
```
if (bitOffset > 0) {
updateCurrentByte();
}
```
outside of the `if (numBytesToSkip >= 0) {` clause. That is because
`numBytesToSkip<0` <=> `(total-(8-bitOffset))<0` means there will be still
unread bits left in `currentByte`
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