[
https://issues.apache.org/jira/browse/BEAM-4461?focusedWorklogId=381936&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-381936
]
ASF GitHub Bot logged work on BEAM-4461:
----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Feb/20 23:06
Start Date: 04/Feb/20 23:06
Worklog Time Spent: 10m
Work Description: TheNeuralBit commented on pull request #10766:
[BEAM-4461] Add Selected.flattenedSchema
URL: https://github.com/apache/beam/pull/10766#discussion_r374966003
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/Select.java
##########
@@ -69,55 +75,117 @@
* }</pre>
*/
@Experimental(Kind.SCHEMAS)
-public class Select<T> extends PTransform<PCollection<T>, PCollection<Row>> {
- private final FieldAccessDescriptor fieldAccessDescriptor;
-
- private Select(FieldAccessDescriptor fieldAccessDescriptor) {
- this.fieldAccessDescriptor = fieldAccessDescriptor;
+public class Select {
+ public static <T> Select.Fields<T> create() {
+ return new Fields<>(FieldAccessDescriptor.create());
}
/** Select a set of top-level field ids from the row. */
- public static <T> Select<T> fieldIds(Integer... ids) {
- return new Select<>(FieldAccessDescriptor.withFieldIds(ids));
+ public static <T> Fields<T> fieldIds(Integer... ids) {
+ return new Fields<>(FieldAccessDescriptor.withFieldIds(ids));
}
/** Select a set of top-level field names from the row. */
- public static <T> Select<T> fieldNames(String... names) {
- return new Select<>(FieldAccessDescriptor.withFieldNames(names));
+ public static <T> Fields<T> fieldNames(String... names) {
+ return new Fields<>(FieldAccessDescriptor.withFieldNames(names));
}
/**
* Select a set of fields described in a {@link FieldAccessDescriptor}.
*
* <p>This allows for nested fields to be selected as well.
*/
- public static <T> Select<T> fieldAccess(FieldAccessDescriptor
fieldAccessDescriptor) {
- return new Select<>(fieldAccessDescriptor);
+ public static <T> Fields<T> fieldAccess(FieldAccessDescriptor
fieldAccessDescriptor) {
+ return new Fields<>(fieldAccessDescriptor);
+ }
+
+ /**
+ * Selects every leaf-level field. This results in a a nested schema being
flattened into a single
+ * top-level schema.
+ */
+ public static <T> Flattened<T> flattenedSchema() {
+ return new Flattened<>();
+ }
+
+ private static class SelectDoFn<T> extends DoFn<T, Row> {
+ private FieldAccessDescriptor fieldAccessDescriptor;
+ private Schema inputSchema;
+ private Schema outputSchema;
+
+ // TODO: This should be the same as resolved so that Beam knows which
fields
+ // are being accessed. Currently Beam only supports wildcard descriptors.
+ // Once BEAM-4457 is fixed, fix this.
+ @FieldAccess("selectFields")
+ final FieldAccessDescriptor fieldAccess =
FieldAccessDescriptor.withAllFields();
Review comment:
It took me a minute to understand what's going on with "selectFields" here
and in `process`. I had no idea that the value on `FieldAccess` could be an id
referencing a member `FieldAccessDescriptor` until I [dug into the
code](https://github.com/apache/beam/blob/2ad1f68/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/ParDo.java#L479-L494).
Let's document that as part of
[BEAM-9217](https://issues.apache.org/jira/browse/BEAM-9217) as well.
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Issue Time Tracking
-------------------
Worklog Id: (was: 381936)
Time Spent: 28h 50m (was: 28h 40m)
> Create a library of useful transforms that use schemas
> ------------------------------------------------------
>
> Key: BEAM-4461
> URL: https://issues.apache.org/jira/browse/BEAM-4461
> Project: Beam
> Issue Type: Sub-task
> Components: sdk-java-core
> Reporter: Reuven Lax
> Assignee: Reuven Lax
> Priority: Major
> Time Spent: 28h 50m
> Remaining Estimate: 0h
>
> e.g. JoinBy(fields). Project, Filter, etc.
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