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https://issues.apache.org/jira/browse/SPARK-52621?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Max Gekk updated SPARK-52621:
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Description:
h2. What
Support {{CAST}} in both directions between {{TIME}} and {{VARIANT}}.
h2. Key design decision
The Spark Variant binary encoding has no native TIME primitive today. The
ticket must pick
and document one of:
* (Preferred) Add a TIME primitive to the Variant encoding so the value and its
precision
round-trip losslessly, consistent with how TIMESTAMP/TIMESTAMP_NTZ are
encoded; or
* Encode TIME as a Variant string (ISO-8601 {{HH:mm:ss[.fffffffff]}}) when no
primitive is
added - lossless textually but typed as string on the way out.
State the chosen representation explicitly in the ticket and in the Variant
spec doc.
h2. Semantics
* {{CAST(time AS VARIANT)}}: produce the representation above, preserving
fractional-seconds
precision.
* {{CAST(variant AS TIME(p))}}: accept the TIME primitive (or a string
parseable by
{{stringToTime}}); truncate fractional seconds to {{p}}; invalid content
follows
{{try_variant_get}}/cast null-vs-error rules for ANSI/non-ANSI.
h2. Scope
* {{VariantGet.checkDataType}} already accepts {{DatetimeType}}; implement the
actual
encode/decode in the Variant build/get paths (the current generic path has no
{{Type.TIME}}).
* Temporal interplay with {{variant_get}}, {{to_variant}},
{{schema_of_variant}}.
h2. Acceptance criteria
* {{cast(cast(t as variant) as time)}} round-trips for precisions 0..9
(coordinate with
the precision-9 extension SPARK-57551).
* Tests in the variant cast suites and SQL golden files.
was:Support casting the TIME data type to/from the VARIANT type.
> Cast TIME to/from VARIANT
> -------------------------
>
> Key: SPARK-52621
> URL: https://issues.apache.org/jira/browse/SPARK-52621
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 4.1.0
> Reporter: Max Gekk
> Priority: Major
> Labels: pull-request-available
>
> h2. What
> Support {{CAST}} in both directions between {{TIME}} and {{VARIANT}}.
> h2. Key design decision
> The Spark Variant binary encoding has no native TIME primitive today. The
> ticket must pick
> and document one of:
> * (Preferred) Add a TIME primitive to the Variant encoding so the value and
> its precision
> round-trip losslessly, consistent with how TIMESTAMP/TIMESTAMP_NTZ are
> encoded; or
> * Encode TIME as a Variant string (ISO-8601 {{HH:mm:ss[.fffffffff]}}) when no
> primitive is
> added - lossless textually but typed as string on the way out.
> State the chosen representation explicitly in the ticket and in the Variant
> spec doc.
> h2. Semantics
> * {{CAST(time AS VARIANT)}}: produce the representation above, preserving
> fractional-seconds
> precision.
> * {{CAST(variant AS TIME(p))}}: accept the TIME primitive (or a string
> parseable by
> {{stringToTime}}); truncate fractional seconds to {{p}}; invalid content
> follows
> {{try_variant_get}}/cast null-vs-error rules for ANSI/non-ANSI.
> h2. Scope
> * {{VariantGet.checkDataType}} already accepts {{DatetimeType}}; implement
> the actual
> encode/decode in the Variant build/get paths (the current generic path has
> no
> {{Type.TIME}}).
> * Temporal interplay with {{variant_get}}, {{to_variant}},
> {{schema_of_variant}}.
> h2. Acceptance criteria
> * {{cast(cast(t as variant) as time)}} round-trips for precisions 0..9
> (coordinate with
> the precision-9 extension SPARK-57551).
> * Tests in the variant cast suites and SQL golden files.
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