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Lei, HUANG
c6b10bfbb9
* feat(function): add Welford stddev functions Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * test(function): cover merged Welford time windows Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * refactor(function): use stddev_pop SQL names Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * fix(function): make Welford arithmetic partition-stable Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * fix(function): reject invalid singleton Welford states Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * test(function): pin Welford state compatibility Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * refactor(function): remove unreachable variance clamp Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * fix(function): reject DISTINCT Welford aggregates Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> * test(compat): bound Welford downgrade targets Signed-off-by: Lei, HUANG <ratuthomm@gmail.com> --------- Signed-off-by: Lei, HUANG <ratuthomm@gmail.com>
22 lines
508 B
Plaintext
22 lines
508 B
Plaintext
-- Direct calculation from each state persisted by the old binary.
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SELECT grp, stddev_pop_calc(state) AS stddev
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FROM stddev_states
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ORDER BY grp;
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+-----+--------+
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| grp | stddev |
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+-----+--------+
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| 0 | 0.5 |
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| 1 | 0.5 |
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+-----+--------+
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-- Merge all persisted states with the new binary before calculating.
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SELECT stddev_pop_calc(stddev_pop_merge(state)) AS stddev
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FROM stddev_states;
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+-------------------+
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| stddev |
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+-------------------+
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| 1.118033988749895 |
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+-------------------+
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