tustvold commented on code in PR #2999:
URL: https://github.com/apache/arrow-rs/pull/2999#discussion_r1014596963
##########
parquet/src/column/reader/decoder.rs:
##########
@@ -323,41 +368,153 @@ impl DefinitionLevelDecoder for ColumnLevelDecoderImpl {
) -> Result<(usize, usize)> {
let mut level_skip = 0;
let mut value_skip = 0;
- match self.decoder.as_mut().unwrap() {
- LevelDecoderInner::Packed(reader, bit_width) => {
- for _ in 0..num_levels {
- // Values are delimited by max_def_level
- if max_def_level
- == reader
- .get_value::<i16>(*bit_width as usize)
- .expect("Not enough values in Packed
ColumnLevelDecoderImpl.")
- {
- value_skip += 1;
- }
- level_skip += 1;
- }
- }
- LevelDecoderInner::Rle(reader) => {
- for _ in 0..num_levels {
- if let Some(level) = reader
- .get::<i16>()
- .expect("Not enough values in Rle
ColumnLevelDecoderImpl.")
- {
- // Values are delimited by max_def_level
- if level == max_def_level {
- value_skip += 1;
- }
- }
- level_skip += 1;
+ while level_skip < num_levels {
+ let remaining_levels = num_levels - level_skip;
+
+ if self.buffer.is_empty() {
+ // Only read number of needed values
+ self.read_to_buffer(remaining_levels.min(SKIP_BUFFER_SIZE))?;
+ if self.buffer.is_empty() {
+ // Reached end of page
+ break;
}
}
+ let to_read = self.buffer.len().min(remaining_levels);
+
+ level_skip += to_read;
+ value_skip += self.buffer[..to_read]
+ .iter()
+ .filter(|x| **x == max_def_level)
+ .count();
+
+ self.split_off_buffer(to_read)
}
+
Ok((value_skip, level_skip))
}
}
impl RepetitionLevelDecoder for ColumnLevelDecoderImpl {
- fn skip_rep_levels(&mut self, _num_records: usize) -> Result<(usize,
usize)> {
- Err(nyi_err!("https://github.com/apache/arrow-rs/issues/1792";))
+ fn skip_rep_levels(&mut self, num_records: usize) -> Result<(usize,
usize)> {
+ let mut level_skip = 0;
+ let mut record_skip = 0;
+
+ loop {
+ if self.buffer.is_empty() {
+ // Read SKIP_BUFFER_SIZE as we don't know how many to read
+ self.read_to_buffer(SKIP_BUFFER_SIZE)?;
+ if self.buffer.is_empty() {
+ // Reached end of page
+ break;
+ }
+ }
+
+ let mut to_skip = 0;
+ while to_skip < self.buffer.len() && record_skip != num_records {
+ if self.buffer[to_skip] == 0 {
+ record_skip += 1;
+ }
+ to_skip += 1;
+ }
+
+ // Find end of record
+ while to_skip < self.buffer.len() && self.buffer[to_skip] != 0 {
+ to_skip += 1;
+ }
+
+ level_skip += to_skip;
+ if to_skip >= self.buffer.len() {
Review Comment:
Yeah, the hope is that >= helps LLVM elide bound checks that follow. Not
sure it makes any difference, just habit 😅
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