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https://issues.apache.org/jira/browse/BEAM-5918?focusedWorklogId=162653&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-162653
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ASF GitHub Bot logged work on BEAM-5918:
----------------------------------------
Author: ASF GitHub Bot
Created on: 05/Nov/18 18:23
Start Date: 05/Nov/18 18:23
Worklog Time Spent: 10m
Work Description: kennknowles commented on a change in pull request
#6888: [BEAM-5918] Add Cast transform for Rows
URL: https://github.com/apache/beam/pull/6888#discussion_r230854619
##########
File path: sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/Schema.java
##########
@@ -338,6 +338,47 @@ public boolean isMapType() {
public boolean isCompositeType() {
return COMPOSITE_TYPES.contains(this);
}
+
+ public boolean isSubtypeOf(TypeName other) {
+ return other.isSupertypeOf(this);
+ }
+
+ public boolean isSupertypeOf(TypeName other) {
Review comment:
In #6861 nullability is added for array elements and map values. It isn't
expressed in the most natural "type system" way, but we should move towards
treating a nullable `T` as `OPTIONAL<T>` with automatic coercion to `T` rather
than treating it as just a `T` with nullability as a side condition. It
requires a fairly significant refactor to do so. Just something to keep in
mind. It would affect this sub/supertype check.
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Issue Time Tracking
-------------------
Worklog Id: (was: 162653)
Time Spent: 4h 20m (was: 4h 10m)
> Add Cast transform for Rows
> ---------------------------
>
> Key: BEAM-5918
> URL: https://issues.apache.org/jira/browse/BEAM-5918
> Project: Beam
> Issue Type: Improvement
> Components: sdk-java-core
> Reporter: Gleb Kanterov
> Assignee: Gleb Kanterov
> Priority: Major
> Time Spent: 4h 20m
> Remaining Estimate: 0h
>
> There is a need for a generic transform that given two Row schemas will
> convert rows between them. There must be a possibility to opt-out from
> certain kind of conversions, for instance, converting ints to shorts can
> cause overflow. Another example, a schema could have a nullable field, but
> never have NULL value in practice, because it was filtered out.
> What is needed:
> - widening values (e.g., int -> long)
> - narrowwing (e.g., int -> short)
> - runtime check for overflow while narrowing
> - ignoring nullability (nullable=true -> nullable=false)
> - weakening nullability (nullable=false -> nullable=true)
> - projection (Schema(a: Int32, b: Int32) -> Schema(a: Int32))
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