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https://issues.apache.org/jira/browse/SPARK-47412?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17836009#comment-17836009
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Gideon P edited comment on SPARK-47412 at 4/11/24 5:30 AM:
-----------------------------------------------------------
Confirming expected behavior:
According to "Collation Support in Spark" word documpend, padding functions
will be "pass through". That is to say if both or one of the string parameters
to LPAD/RPAD have either the same collation or a collation that overrides the
other ( Explicit collation has precedence over Implicit collation which has
precedence over Default location), the return type will have that collation.
But in terms of _value_, that will be the same as it would be prior to
collations. Similar to substring/left/right.
And If the two string parameters to pad functions have different collations,
and both explicitly defined (or both implicitly defined), the function would be
expected to throw an exception, right?
[~uros-db] please confirm. Thanks!
was (Author: JIRAUSER304403):
Confirming expected behavior:
According to "Collation Support in Spark" word documpend, padding functions
will be "pass through". That is to say if both or one of the string parameters
to LPAD/RPAD have either the same collation or a collation that overrides the
other ( Explicit collation has precedence over Implicit collation which has
precedence over Default location), the return type will have that collation.
But in terms of _value_, that will be the same as it would be prior to
collations. Similar to substring/left/right.
And If different collations of the same precedence, the function would be
expected to throw an exception, right?
[~uros-db] please confirm. Thanks!
> StringLPad, StringRPad (all collations)
> ---------------------------------------
>
> Key: SPARK-47412
> URL: https://issues.apache.org/jira/browse/SPARK-47412
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 4.0.0
> Reporter: Uroš Bojanić
> Priority: Major
>
> Enable collation support for the *StringLPad* & *StringRPad* built-in string
> functions in Spark. First confirm what is the expected behaviour for these
> functions when given collated strings, then move on to the implementation
> that would enable handling strings of all collation types. Implement the
> corresponding unit tests (CollationStringExpressionsSuite) and E2E tests
> (CollationSuite) to reflect how this function should be used with collation
> in SparkSQL, and feel free to use your chosen Spark SQL Editor to experiment
> with the existing functions to learn more about how they work. In addition,
> look into the possible use-cases and implementation of similar functions
> within other other open-source DBMS, such as
> [PostgreSQL|https://www.postgresql.org/docs/].
>
> The goal for this Jira ticket is to implement the *StringLPad* & *StringRPad*
> functions so that they support all collation types currently supported in
> Spark. To understand what changes were introduced in order to enable full
> collation support for other existing functions in Spark, take a look at the
> Spark PRs and Jira tickets for completed tasks in this parent (for example:
> Contains, StartsWith, EndsWith).
>
> Read more about ICU [Collation Concepts|http://example.com/] and
> [Collator|http://example.com/] class. Also, refer to the Unicode Technical
> Standard for
> [collation|https://www.unicode.org/reports/tr35/tr35-collation.html#Collation_Type_Fallback].
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