Condition pushdown for rand() > value multiply the probabilities #17244
Description
Describe the bug
If we pushdown сonditions with rand() function in subquery, we actually multiply the probabilities.
How to reproduce
Clickhouse version 20.12
SELECT count(*)
FROM
(
SELECT number
FROM
(
SELECT number
FROM numbers(1000000)
)
WHERE rand64() < (0.01 * 18446744073709552000.)
)
Query id: 13c8ae5e-ed90-4610-b7c3-8e8d3bf27f12
┌─count()─┐
│ 114 │
└─────────┘
1 rows in set. Elapsed: 0.008 sec. Processed 1.05 million rows, 8.38 MB (136.06 million rows/s., 1.09 GB/s.)
EXPLAIN SYNTAX
SELECT count(*)
FROM
(
SELECT number
FROM
(
SELECT number
FROM numbers(1000000)
)
WHERE rand64() < (0.01 * 18446744073709552000.)
)
Query id: 6036d15a-32ba-4161-a6fe-41eff40af246
┌─explain─────────────────────────────────────────────────┐
│ SELECT count() │
│ FROM │
│ ( │
│ SELECT number │
│ FROM │
│ ( │
│ SELECT number │
│ FROM numbers(1000000) │
│ WHERE rand64() < (0.01 * 18446744073709552000.) │
│ ) │
│ WHERE rand64() < (0.01 * 18446744073709552000.) │
│ ) │
└─────────────────────────────────────────────────────────┘