[SQL] Implement (partially) FIRST_VALUE and LAST_VALUE window aggregation functions#3924
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mihaibudiu merged 1 commit intomainfrom Apr 23, 2025
Merged
[SQL] Implement (partially) FIRST_VALUE and LAST_VALUE window aggregation functions#3924mihaibudiu merged 1 commit intomainfrom
FIRST_VALUE and LAST_VALUE window aggregation functions#3924mihaibudiu merged 1 commit intomainfrom
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mihaibudiu
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FIRST_VALUE and LAST_VALUE window aggregation functions
…tion functions Signed-off-by: Mihai Budiu <mbudiu@feldera.com>
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Apr 23, 2025
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We support
FIRST_VALUEandLAST_VALUEonly if they are used with anUNLIMITED RANGE.This is still useful, because
FIRST_VALUEis generated by the Calcite decorrelator when decorrelating queries that contain(ORDER BY ... LIMIT 1). This enables us to support such queries.This partially fixes #3918.
Testing this has uncovered some bugs related to the sorting of
NULLvalues and the handling ofNULLS LASTandNULLS FIRST. Some tests were passing although they were incorrect, because they were tested on a system whereNULLs compare largest. In our SQL dialectNULLs compare smallest (conveniently matches Rust, and cannot be easily changed).We will write more tests for sorting as part of #3922