Fix grouped MAX for non-positive floating-point values - #18300
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JackieTien97 merged 1 commit intoJul 24, 2026
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JackieTien97
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CritasWang
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I think this PR needs to be updated to 2.0.11 |
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The milliseconds aggregation path projected MAX over the numeric COALESCE expression. IoTDB's grouped max accumulator seeds FLOAT/DOUBLE state with Float/Double.MIN_VALUE -- the smallest positive value, not the most negative one -- and only marks a group initialized when value >= state, so a bucket whose numeric maximum is zero or negative comes back NULL. This DAO reads a NULL aggregate as an empty bucket and skips it, so a MAX downsampling query over, for example, a sub-zero sensor silently lost whole buckets instead of failing. Project -MIN(-x) instead: the grouped min accumulator seeds with MAX_VALUE and is not affected, and IEEE-754 negation is exact, so the result is identical over finite values on servers with and without the upstream fix. The projection is shared with the calendar path, whose non-grouped accumulators track an explicit initialized flag rather than a sentinel, so the substitution is exact there too and an empty bucket still yields NULL. The long and string channels are already correct and keep using MAX. Verified against apache/iotdb 2.0.8 and 2.0.10 containers. See apache/iotdb#18300, fixed on master but not yet in a released version. Signed-off-by: Zihan Dai <99155080+PDGGK@users.noreply.github.com>
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The milliseconds aggregation path projected MAX over the numeric COALESCE expression. IoTDB's grouped max accumulator seeds FLOAT/DOUBLE state with Float/Double.MIN_VALUE -- the smallest positive value, not the most negative one -- and only marks a group initialized when value >= state, so a bucket whose numeric maximum is zero or negative comes back NULL. This DAO reads a NULL aggregate as an empty bucket and skips it, so a MAX downsampling query over, for example, a sub-zero sensor silently lost whole buckets instead of failing. Project -MIN(-x) instead: the grouped min accumulator seeds with MAX_VALUE and is not affected, and IEEE-754 negation is exact, so the result is identical over finite values on servers with and without the upstream fix. The projection is shared with the calendar path, whose non-grouped accumulators track an explicit initialized flag rather than a sentinel, so the substitution is exact there too and an empty bucket still yields NULL. The long and string channels are already correct and keep using MAX. Verified against apache/iotdb 2.0.8 and 2.0.10 containers. See apache/iotdb#18300, fixed on master but not yet in a released version. Signed-off-by: Zihan Dai <99155080+PDGGK@users.noreply.github.com>
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Description
Fix table-model grouped
MAXreturningNULLwhen everyFLOATorDOUBLEvalue in a group is zero or negative.
GroupedMaxAccumulatorinitialized floating-point states withFloat.MIN_VALUEand
Double.MIN_VALUE. In Java, those constants are the smallest positivevalues, not the most negative values. As a result, non-positive inputs never
initialized the group state, and the final result was emitted as
NULL.MAX_BYwas unaffected because its implementation explicitly handles the firstinput value.
Changes
MAXstates with negative infinity.raw and intermediate inputs.
NULL.aggregation path.
User impact
Grouped
MAX(FLOAT)andMAX(DOUBLE)now return the correct value for groupswhose maximum is non-positive, including all-zero groups.
Validation
mvn clean test -pl iotdb-core/calc-commons \ -Dtest=GroupedMaxAccumulatorTest mvn clean verify -Drat.skip=true -DskipUTs \ -Dit.test=IoTDBTableAggregationNonStreamIT#maxNonPositiveFloatingPointTest \ -DfailIfNoTests=false -Dfailsafe.failIfNoSpecifiedTests=false \ -pl integration-test -am -PTableSimpleIT -P with-integration-testsThe targeted integration test passed and the 37-module clean reactor build
completed successfully.