SQL

success
SQL
SELECT *
FROM trips
LIMIT 20

Dataset trips · ./data/trips

success 101.34 ms 20 rows 100.0% of dataset bytes read Run #6 details
20 rows 9 columns
Row trip_idpickup_hourpassengersdistancepricetippaymentregiondate
1 012137.91118.5218.03cardEU2024-01-01
2 113116.1140.46NULLwalletEU2024-01-01
3 21224.975.67NULLwalletEU2024-01-01
4 3844.0911.781.83cashEU2024-01-01
5 41623.6716.8NULLwalletEU2024-01-01
6 515413.1453.9615.23cashEU2024-01-01
7 61223.2114.37NULLwalletEU2024-01-01
8 79317.644.717.3cardEU2024-01-01
9 815319.1642.616.02cardEU2024-01-01
10 91134.012.14NULLwalletEU2024-01-01
11 1018114.6846.36NULLwalletEU2024-01-01
12 116136.93133.9234.7cashEU2024-01-01
13 121610.455.62NULLwalletEU2024-01-01
14 134226.873.7311.26cashEU2024-01-01
15 14916.9626.410.33cardEU2024-01-01
16 154431.36108.7316.81cashEU2024-01-01
17 16317.1534.9910.46cardEU2024-01-01
18 1719321.9175.5613.77cardEU2024-01-01
19 18811.028.451.45cardEU2024-01-01
20 1917330.6299.01NULLcashEU2024-01-01
Bytes scanned / dataset bytes
100.0%
5.9 MB came off disk, out of 5.9 MB of compressed dataset bytes.
Execution
Duration 101.34 ms
Rows returned 20
Rows scanned 300000
Files pruned 0 of 15 files
Row-groups pruned 0 of 120 row-groups
Columns read 7 of 7 columns
Why it read that much
  • Nothing was pruned: this query had no filter the engine could push down, so every file, row-group and column had to be read. This is the baseline the other demo queries are measured against.
Where the bytes went
A naive full scan
5.9 MB
every byte of every column in every file
Actually read
5.9 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