SQL

success
SQL
SELECT COUNT(*) AS total
FROM trips
WHERE trip_id > 2374

Dataset trips · ./data/trips

success 31.97 ms 1 row 26.9% of dataset bytes read Run #3 details
1 row 1 column
Row total
1 297,625
Bytes scanned / dataset bytes
26.9%
1.6 MB came off disk, out of 5.9 MB of compressed dataset bytes.
Execution
Duration 31.97 ms
Rows returned 1
Rows scanned 300000
Files pruned 0 of 15 files
Row-groups pruned 0 of 120 row-groups
Columns read 1 of 7 columns
Why it read that much
  • Only 1 of 7 columns came off disk — the other 6 were never referenced, and Parquet is columnar.
Where the bytes went
A naive full scan
5.9 MB
every byte of every column in every file
Columns not referenced
4.3 MB
Parquet is columnar, so these were never touched
Actually read
1.6 MB
what came off disk to answer the query

The middle bars are bytes a scan-everything engine would have read and this one did not. They add up to the full scan exactly — it is one number decomposed, not four separate measurements.

Row-group map (120 of 120 read)
region=EU/date=2024-01-01
region=EU/date=2024-01-02
region=EU/date=2024-01-03
region=EU/date=2024-01-04
region=EU/date=2024-01-05
region=US/date=2024-01-01
region=US/date=2024-01-02
region=US/date=2024-01-03
region=US/date=2024-01-04
region=US/date=2024-01-05
region=APAC/date=2024-01-01
region=APAC/date=2024-01-02
region=APAC/date=2024-01-03
region=APAC/date=2024-01-04
region=APAC/date=2024-01-05
read skipped — footer stats proved no match file never opened, so its row-group count is unknown by design