nuno-faria commented on PR #17275:
URL: https://github.com/apache/datafusion/pull/17275#issuecomment-3266643038
I found a potential performance regression with `parquet 56.1.0`. Now more
data pages will be returned if their size is less than the execution batch
size. For example:
```rust
use datafusion::error::Result;
use datafusion::prelude::{ParquetReadOptions, SessionConfig, SessionContext};
#[tokio::main]
async fn main() -> Result<()> {
let config = SessionConfig::new().with_target_partitions(1);
let ctx = SessionContext::new_with_config(config);
ctx.sql("set datafusion.execution.parquet.pushdown_filters = true")
.await?
.collect()
.await?;
ctx.sql(
"
copy (
select i as k
from generate_series(1, 1000000) as t(i)
order by k
) to 't.parquet'
options (MAX_ROW_GROUP_SIZE 100000, DATA_PAGE_ROW_COUNT_LIMIT 1000,
WRITE_BATCH_SIZE 1000, DICTIONARY_ENABLED FALSE);",
)
.await?
.collect()
.await?;
ctx.register_parquet("t", "t.parquet", ParquetReadOptions::new())
.await?;
ctx.sql("explain analyze select k from t where k = 123456")
.await?
.show()
.await?;
Ok(())
}
```
With `parquet 56.0.0`:
```
metrics=[..., bytes_scanned=1273, ...]
# some debug info showing that a single page is retrieved
total=1273
ranges=[132974..134247]
```
With `parquet 56.1.0`:
```
metrics=[..., bytes_scanned=9929, ...]
# some debug info showing that multiple pages are retrieved
total=9929
ranges=[125400..126482, 126482..127564, 127564..128646, 128646..129728,
129728..130810, 130810..131892, 131892..132974, 132974..134247, 134247..135329]
```
I think this is a consequence of
https://github.com/apache/arrow-rs/pull/7850, more specifically
https://github.com/apache/arrow-rs/blame/0c7cb2ac3f3132216a08fd557f9b1edc7f90060f/parquet/src/arrow/arrow_reader/selection.rs#L445.
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