Filter all-null FIELD columns before tablet insert in Java/C++/Python… - #18533
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hongzhi-gao wants to merge 5 commits into
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Filter all-null FIELD columns before tablet insert in Java/C++/Python…#18533hongzhi-gao wants to merge 5 commits into
hongzhi-gao wants to merge 5 commits into
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… clients Skip or shrink tablets that only contain null FIELD values so insert paths avoid shipping unused measurement columns across languages.
jt2594838
reviewed
Aug 27, 2026
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| static bool isColumnAllNull(const BitMap& bitMap, size_t rowSize) { | ||
| if (rowSize == 0) { | ||
| return false; | ||
| } | ||
| if (bitMap.getSize() == rowSize && bitMap.isAllMarked()) { | ||
| return true; | ||
| } | ||
| for (size_t row = 0; row < rowSize; row++) { | ||
| if (!bitMap.isMarked(row)) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } |
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Why is bitMap.isAllMarked not enough?
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BitMap is sized to maxRowNumber, not rowSize. When rowSize < maxRowNumber, tail bits are unmarked, so isAllMarked() returns false even if all active rows are null. We only use it when getSize() == rowSize.
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Is it possible to add BitMap.isAllMarked(int start, int end) to accelerate this iteration?
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| auto filteredOut = std::make_shared<Tablet>(tablet.deviceId, keptSchemas, keptColumnTypes, | ||
| tablet.maxRowNumber, tablet.isAligned); | ||
| filteredOut->deleteColumns(); |
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Not create-and-delete or copy. May add a constructor for this.
Table-model tablet inserts may carry only time and tag/attribute columns. Do not treat all-null FIELD columns as an empty tablet when non-FIELD columns remain, and clarify buildInsertTabletReq skip semantics.
…olumns. Add a private constructor and createWithoutValueColumns to build tablets without pre-allocating value columns, fix bitmap null-check bounds, and update the Java table-model test constructor.
BitMap is sized to maxRowNumber, so a full-map isAllMarked() can miss all-null FIELD columns when rowSize is smaller. Use isRangeAllMarked on [0, rowSize) in the Java, C++, and Python clients.
A never-written column is treated as all-null; dropping it skipped the existing measurement-name check and omitted timeseries that tests expect.
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Description
Before inserting a Tablet, drop FIELD columns that are entirely null within
[0, rowSize). TAG / ATTRIBUTE columns are always kept. This avoids shipping unused measurement columns when the client schema is wide but each batch only fills a subset of fields.Behavior
Multi-language clients
Aligned the same logic in Java / C++ / Python Session insert tablet paths (
insertTablet/insertTablets/ aligned / relational where applicable). C API goes through the C++ Session, so no separate implementation.Design notes
SessionUtils.filterNullColumns(Java / C++) andfilter_null_columns(Python), and is invoked when building insert requests after sort.std::shared_ptr<const Tablet>(non-owning empty deleter for the original tablet; owning shared_ptr for a filtered copy) instead of a raw pointer + out-parameter.This PR has:
Key changed/added classes (or packages if there are too many classes) in this PR
org.apache.iotdb.session.util.SessionUtilsorg.apache.iotdb.session.Sessioniotdb-client/client-cppSessionUtils::filterNullColumns/Sessioniotdb.utils.SessionUtils(Python)SessionUtilsTest(Java),sessionUtilsTest(C++),test_session_utils.py(Python)