test: add parity tests for spark.sql.legacy.timeParserPolicy#4181
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andygrove wants to merge 2 commits intoapache:mainfrom
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test: add parity tests for spark.sql.legacy.timeParserPolicy#4181andygrove wants to merge 2 commits intoapache:mainfrom
andygrove wants to merge 2 commits intoapache:mainfrom
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…olicy Adds parity tests for Spark's timeParserPolicy config (CORRECTED/LEGACY) across CAST(string AS date/timestamp), to_date, to_timestamp, unix_timestamp, from_unixtime, and date_format. Two tests for string-to-timestamp are marked ignore because Comet's native ISO parser rejects inputs like "2020-1-1 1:2:3" that Spark accepts under LEGACY. Flip ignore -> test once Comet honors the policy.
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Summary
Adds a new test suite (
CometTimeParserPolicySuite) that verifies Comet matches Spark under non-default values ofspark.sql.legacy.timeParserPolicy(CORRECTEDandLEGACY) for:CAST(string AS date/timestamp),to_date,to_timestamp,unix_timestamp,from_unixtime, anddate_format.This is draft / exploratory — the goal is to document current behavior gaps rather than fix them. It's part of a broader audit of Spark configs whose non-default values may produce divergent results in Comet.
Findings
Running on Spark 4.0:
CAST(string AS date)CAST(string AS timestamp)ignoredto_date(s)without patternto_date(s, pattern)ParseToDateserde)to_timestamp(s)without patternignoredto_timestamp(s, pattern)unix_timestamp(s, pattern)from_unixtime(long, pattern)Incompatible(None)default fallback)date_format(date, pattern)The two
ignored tests show concrete divergence:2020-1-1 1:2:32020-01-01 01:02:03.0nullComet's native ISO parser in
native/spark-expr/src/conversion_funcs/string.rsrejects the single-digit month/day/hour/minute/second formats that Spark'sSimpleDateFormataccepts under LEGACY. The config is not read anywhere in Comet.Passing tests mostly represent cases where Comet falls back to Spark (pattern-based functions with no serde handler, or
Incompatible(None)default). They're still useful as regression guards.Context
Follow-up to a broader audit of Spark configs whose non-default values can silently produce wrong results in Comet — other candidates:
parquet.datetimeRebaseModeInRead,parquet.int96RebaseModeInRead,parquet.binaryAsString,mapKeyDedupPolicy.Test plan
-Pspark-4.0 -Pscala-2.13CometTimeParserPolicySuitelocally — 7 pass, 2ignoreignored tests drive a fix (honor the policy) or explicit fallback (timeParserPolicy != CORRECTED→ fall back to Spark)