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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/12/05 21:25:58 UTC
[GitHub] [arrow-datafusion] isidentical opened a new pull request, #4521: Fix limited statistic collection accross files with no stats
isidentical opened a new pull request, #4521:
URL: https://github.com/apache/arrow-datafusion/pull/4521
# Which issue does this PR close?
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Closes #4323.
# Rationale for this change
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Even in the cases where none of the files included stats/byte size information, `get_statistics_with_limit` was generating statistics with the claims of zero rows / zero bytes. This PR fixes it to only include the number of rows when it is known.
# What changes are included in this PR?
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There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR.
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For preserving the old relaxed behavior, this PR changes the collection to include row/byte count information when any of them are present in any of the files. If it is only present in even one file, that is enough for the listing (all the others are counted towards zero rows, which is the existing behavior).
# Are these changes tested?
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Yes.
# Are there any user-facing changes?
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No.
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[GitHub] [arrow-datafusion] alamb commented on pull request #4521: Fix limited statistic collection accross files with no stats
Posted by GitBox <gi...@apache.org>.
alamb commented on PR #4521:
URL: https://github.com/apache/arrow-datafusion/pull/4521#issuecomment-1353665777
cc @mingmwang
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #4521: Fix limited statistic collection accross files with no stats
Posted by GitBox <gi...@apache.org>.
alamb commented on code in PR #4521:
URL: https://github.com/apache/arrow-datafusion/pull/4521#discussion_r1050098588
##########
datafusion/core/src/datasource/listing/table.rs:
##########
@@ -747,6 +747,30 @@ mod tests {
Ok(())
}
+ #[tokio::test]
+ async fn load_table_stats_when_no_stats() -> Result<()> {
+ let testdata = crate::test_util::parquet_test_data();
+ let filename = format!("{}/{}", testdata, "alltypes_plain.parquet");
+ let table_path = ListingTableUrl::parse(filename).unwrap();
+
+ let ctx = SessionContext::new();
+ let state = ctx.state();
+
+ let opt = ListingOptions::new(Arc::new(ParquetFormat::new(ctx.config_options())))
+ .with_collect_stat(false);
+ let schema = opt.infer_schema(&state, &table_path).await?;
+ let config = ListingTableConfig::new(table_path)
+ .with_listing_options(opt)
+ .with_schema(schema);
+ let table = ListingTable::try_new(config)?;
+
+ let exec = table.scan(&state, None, &[], None).await?;
+ assert_eq!(exec.statistics().num_rows, None);
Review Comment:
👍
##########
datafusion/core/src/datasource/mod.rs:
##########
@@ -47,29 +47,42 @@ use futures::StreamExt;
/// Get all files as well as the file level summary statistics (no statistic for partition columns).
/// If the optional `limit` is provided, includes only sufficient files.
/// Needed to read up to `limit` number of rows.
-/// TODO fix case where `num_rows` and `total_byte_size` are not defined (stat should be None instead of Some(0))
pub async fn get_statistics_with_limit(
all_files: impl Stream<Item = Result<(PartitionedFile, Statistics)>>,
file_schema: SchemaRef,
limit: Option<usize>,
) -> Result<(Vec<PartitionedFile>, Statistics)> {
let mut result_files = vec![];
- let mut total_byte_size = 0;
let mut null_counts = vec![0; file_schema.fields().len()];
let mut has_statistics = false;
let (mut max_values, mut min_values) = create_max_min_accs(&file_schema);
- let mut num_rows = 0;
let mut is_exact = true;
+
+ // The number of rows and the total byte size can be calculated as long as
+ // at least one file has them. If none of the files provide them, then they
+ // will be omitted from the statistics. The missing values will be counted
+ // as zero.
+ let mut num_rows = None;
+ let mut total_byte_size = None;
+
// fusing the stream allows us to call next safely even once it is finished
let mut all_files = Box::pin(all_files.fuse());
while let Some(res) = all_files.next().await {
let (file, file_stats) = res?;
result_files.push(file);
is_exact &= file_stats.is_exact;
- num_rows += file_stats.num_rows.unwrap_or(0);
- total_byte_size += file_stats.total_byte_size.unwrap_or(0);
+ num_rows = if let Some(num_rows) = num_rows {
+ Some(num_rows + file_stats.num_rows.unwrap_or(0))
+ } else {
+ file_stats.num_rows
+ };
+ total_byte_size = if let Some(total_byte_size) = total_byte_size {
+ Some(total_byte_size + file_stats.total_byte_size.unwrap_or(0))
+ } else {
+ file_stats.total_byte_size
+ };
Review Comment:
If you are into a more functional style of coding, you can do something like the following as well
```suggestion
num_rows = num_rows
.map(|num_rows| num_rows + file_stats.num_rows.unwrap_or(0))
.or(file_stats.num_rows);
total_byte_size = total_byte_size
.map(|total_byte_size| total_byte_size + file_stats.total_byte_size.unwrap_or(0))
.or(file_stats.total_byte_size);
```
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[GitHub] [arrow-datafusion] ursabot commented on pull request #4521: Fix limited statistic collection accross files with no stats
Posted by GitBox <gi...@apache.org>.
ursabot commented on PR #4521:
URL: https://github.com/apache/arrow-datafusion/pull/4521#issuecomment-1356184037
Benchmark runs are scheduled for baseline = 8d36529abab500f4effd805e204b78ff0ab03d17 and contender = 067d0443d2167cc33666c6490f383083a1c2b200. 067d0443d2167cc33666c6490f383083a1c2b200 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped :warning: Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] [ec2-t3-xlarge-us-east-2](https://conbench.ursa.dev/compare/runs/bb0da02769ac46b1a162c105189f1c0c...a09167a525864135964f8271f8b35fd2/)
[Skipped :warning: Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] [test-mac-arm](https://conbench.ursa.dev/compare/runs/3526c02763d9483396f4b06764668e4a...e008b570aad1459884df601d0a7f453e/)
[Skipped :warning: Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] [ursa-i9-9960x](https://conbench.ursa.dev/compare/runs/2b0be7985b34467caf81c07aaa58c71c...9c39c5824d034fdaafdd8063b59dce98/)
[Skipped :warning: Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] [ursa-thinkcentre-m75q](https://conbench.ursa.dev/compare/runs/393e3a539d6a4f658a549bd48b7f4b1b...08a3ee3390434162b97171d598e29bdd/)
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java
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[GitHub] [arrow-datafusion] alamb merged pull request #4521: Fix limited statistic collection accross files with no stats
Posted by GitBox <gi...@apache.org>.
alamb merged PR #4521:
URL: https://github.com/apache/arrow-datafusion/pull/4521
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