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https://github.com/GreptimeTeam/greptimedb.git
synced 2026-09-22 13:15:34 +00:00
Dennis Zhuang
47f439ea07
Review follow-up. Two things surfaced once range functions started returning NULL for a window without samples. The filter after a function call required every field column to be non-NULL, so on a multi-field table one field with no samples in a window would drop the other fields' results with it. It now keeps a row when any field has a sample, which is the shape a selector already emits. On a single field column the two predicates are identical. `quantile_over_time` returned NaN rather than NULL for a window without samples, so the row survived that filter. Prometheus returns an empty vector there, so the emptiness check now sits in the range UDF; the shared quantile kernel still yields NaN for an empty slice, matching upstream's `quantile()` helper that `quantile_aggr` depends on. Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
94 lines
2.6 KiB
SQL
94 lines
2.6 KiB
SQL
CREATE TABLE null_samples (
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ts TIMESTAMP(3) TIME INDEX,
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"region" STRING,
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host STRING,
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val DOUBLE,
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PRIMARY KEY ("region", host)
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);
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INSERT INTO null_samples VALUES
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(0, 'empty', 'e', NULL),
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(1000, 'empty', 'e', NULL),
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(0, 'ok', 'o', 1.0),
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(1000, 'ok', 'o', 2.0),
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(2000, 'ok', 'o', 3.0);
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-- The `empty` series has no sample in any window, so it must not reach the aggregation.
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-- SQLNESS SORT_RESULT 3 1
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TQL EVAL (0, 15, '1s') avg by (region) (rate(null_samples[4s]));
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DROP TABLE null_samples;
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CREATE TABLE sparse_samples (
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ts TIMESTAMP(3) TIME INDEX,
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host STRING PRIMARY KEY,
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val DOUBLE
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);
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INSERT INTO sparse_samples VALUES
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(0, 'a', 1.0),
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(1000, 'a', NULL),
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(2000, 'a', NULL),
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(3000, 'a', 4.0);
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-- Every window below holds two samples, 1.0 at 0s and 4.0 at 3s.
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TQL EVAL (3, 3, '1s') rate(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') increase(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') delta(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') idelta(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') irate(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') changes(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') resets(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') avg_over_time(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') stddev_over_time(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') stdvar_over_time(sparse_samples[4s]);
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TQL EVAL (3, 3, '1s') quantile_over_time(0.5, sparse_samples[4s]);
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-- A window whose only slot is NULL holds no sample.
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TQL EVAL (1, 1, '1s') rate(sparse_samples[1s]);
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TQL EVAL (1, 1, '1s') changes(sparse_samples[1s]);
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-- Prometheus returns an empty vector for a range without samples, not NaN.
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TQL EVAL (1, 1, '1s') quantile_over_time(0.5, sparse_samples[1s]);
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DROP TABLE sparse_samples;
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CREATE TABLE multi_field (
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ts TIMESTAMP(3) TIME INDEX,
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host STRING PRIMARY KEY,
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f1 DOUBLE,
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f2 DOUBLE
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);
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INSERT INTO multi_field VALUES
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(0, 'a', 1.0, 10.0),
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(1000, 'a', 2.0, NULL),
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(2000, 'a', 3.0, NULL),
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(3000, 'a', 4.0, 40.0);
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-- f1 and f2 share the same rows but have samples at different timestamps. Dropping the rows
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-- where f2 is NULL would also drop two of f1's samples, so each field is counted separately.
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-- SQLNESS SORT_RESULT 3 1
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TQL EVAL (3, 3, '1s') rate(multi_field[4s]);
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-- f1 has two samples in this window and f2 only one, so f1 keeps its result while f2 is NULL.
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-- SQLNESS SORT_RESULT 3 1
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TQL EVAL (1, 1, '1s') rate(multi_field[4s]);
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-- A selector emits the same shape: the row stays, the field without a sample is NULL.
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-- SQLNESS SORT_RESULT 3 1
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TQL EVAL (1, 1, '1s') multi_field;
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DROP TABLE multi_field;
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