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email-tracker/external/duckdb/test/sql/sample/sample_verification.test_slow
2025-10-24 19:21:19 -05:00

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# name: test/sql/sample/sample_verification.test_slow
# description: Test SAMPLE keyword
# group: [sample]
statement ok
PRAGMA enable_verification;
# verify that it is a sample without replacement (i.e. the same row will never occur more than once in the result)
loop i 0 10
query I
select count(distinct i) from range(10) tbl(i) using sample 5;
----
5
endloop
# specifying a seed leads to repeatable behavior
loop i 0 10
query I nosort reservoirseed
select * from range(100) using sample 10 (reservoir, 250)
----
query I nosort bernoulliseed
select * from range(100) using sample 10% (bernoulli, 250)
----
query I nosort systemseed
select * from range(100) using sample 10% (system, 250)
----
endloop
# specify as sample_size, with reservoir sampling this should give us an exact count (i.e. always 10)
loop i 0 10
query I
select count(*) from range(100) using sample 10% (reservoir)
----
10
endloop