Fix tag index misalignment in read_tsfile when projection pruning removes tag columns

[shuwenwei]

Problem

When projection pruning removes tag columns from the scan node's assignments, constructExternalTsFileDeviceFilter builds a TsTable from the pruned assignments and recomputes tag indices via getTagColumnIndex. This causes subsequent tag columns to be assigned wrong indices.

For example, with tags [tag1, tag2] and a query like:

SELECT time, value FROM read_tsfile(...) WHERE tag2 = 'x'

The optimizer:

1. Prunes tag1 and tag2 from the scan node's assignments (they are not in SELECT)
2. Rebuilds a TsTable containing only tag2
3. Recomputes tag index: tag2 → 0 (should be 1)
4. ExternalTsFileDeviceFilterVisitor reads deviceID.segment(0 + 1) = tag1 instead of deviceID.segment(1 + 1) = tag2

Result: WHERE tag2 = 'x' actually evaluates WHERE tag1 = 'x'.

Fix

Use ExternalTsFileQueryResource.getTableColumnSchema() instead of the pruned scan node getAssignments() when constructing the TsTable for device filter. The query resource always holds the complete, unpruned column schema with correct tag ordering from the initial planning phase.

Changes

• PushPredicateIntoTableScan.java: Change constructExternalTsFileDeviceFilter to build TsTable from the complete table column schema
• IoTDBReadTsFileTableFunctionIT.java: Add testReadTsFileWithTagFilterAndProjectionPruning to verify correct tag filtering when projection prunes tag columns

[Copilot]

Pull request overview

Fixes incorrect tag filtering for read_tsfile(...) when optimizer projection pruning removes tag columns from an ExternalTsFileScanNode’s assignments, which previously caused tag index recomputation against a pruned schema and led to mis-addressing deviceID.segment(tagIndex + 1).

Changes:

• Update PushPredicateIntoTableScan.constructExternalTsFileDeviceFilter to build the TsTable from ExternalTsFileQueryResource.getTableColumnSchema() (complete, unpruned schema) instead of the scan node’s pruned assignments.
• Add an integration test that reproduces the tag-index misalignment under projection pruning and verifies correct tag filtering behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/optimizations/PushPredicateIntoTableScan.java	Builds device-filter TsTable from the full external TsFile table schema to preserve correct tag ordering/indices after column pruning.
integration-test/src/test/java/org/apache/iotdb/relational/it/query/recent/IoTDBReadTsFileTableFunctionIT.java	Adds an IT case ensuring tag predicates still match the correct tag values when tag columns are pruned from projection.

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[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 42.41%. Comparing base (350c6c7) to head (9b31558).
⚠️ Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
...nner/optimizations/PushPredicateIntoTableScan.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18191      +/-   ##
============================================
+ Coverage     41.93%   42.41%   +0.47%     
  Complexity      318      318              
============================================
  Files          5312     5321       +9     
  Lines        375370   376605    +1235     
  Branches      48474    48716     +242     
============================================
+ Hits         157423   159720    +2297     
+ Misses       217947   216885    -1062     

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