SQL functions for random sampling.
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- See also
- For an overview of random-sampling functions, see the module description Random Sampling.
◆ gamma_random()
float8 gamma_random |
( |
float8 |
alpha | ) |
|
◆ index_weighted_sample()
integer index_weighted_sample |
( |
float8 |
[] | ) |
|
◆ poisson_random()
integer poisson_random |
( |
float8 |
mean | ) |
|
◆ weighted_sample() [1/2]
aggregate bytea8 weighted_sample |
( |
bigint |
value, |
|
|
float8 |
weight |
|
) |
| |
- Parameters
-
value | Value of row. Uniqueness is not enforced. If a value occurs multiple times, the probability of sampling this value is proportional to the sum of its weights. |
weight | Weight for row. A negative value here is treated has zero weight. |
- Returns
identifier
of the selected row. The probability of sampling any particular row (value, weight)
is weight/SUM(weight)
.
◆ weighted_sample() [2/2]
aggregate bytea8 weighted_sample |
( |
float8 [] |
value, |
|
|
float8 |
weight |
|
) |
| |
◆ weighted_sample_final_int64()
bigint weighted_sample_final_int64 |
( |
bytea8 |
state | ) |
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◆ weighted_sample_final_vector()
float8 [] weighted_sample_final_vector |
( |
bytea8 |
state | ) |
|
◆ weighted_sample_merge_int64()
bytea8 weighted_sample_merge_int64 |
( |
bytea8 |
state_left, |
|
|
bytea8 |
state_right |
|
) |
| |
◆ weighted_sample_merge_vector()
bytea8 weighted_sample_merge_vector |
( |
bytea8 |
state_left, |
|
|
bytea8 |
state_right |
|
) |
| |
◆ weighted_sample_transition_int64()
bytea8 weighted_sample_transition_int64 |
( |
bytea8 |
state, |
|
|
bigint |
value, |
|
|
float8 |
weight |
|
) |
| |
◆ weighted_sample_transition_vector()
bytea8 weighted_sample_transition_vector |
( |
bytea8 |
state, |
|
|
float8 [] |
value, |
|
|
float8 |
weight |
|
) |
| |