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https://issues.apache.org/jira/browse/FLINK-19038?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17185585#comment-17185585
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Nicholas Jiang edited comment on FLINK-19038 at 8/27/20, 3:37 AM:
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[~twalthr],[~dwysakowicz],
{code:java}
private SortQueryOperation validateAndGetChildSort(QueryOperation child,
PostResolverFactory postResolverFactory) {
final SortQueryOperation previousSort;
if (child instanceof SortQueryOperation) {
previousSort = (SortQueryOperation) child;
} else {
previousSort = (SortQueryOperation) createSort(Collections.emptyList(),
child, postResolverFactory);
}
if ((previousSort).getFetch() != -1) {
throw new ValidationException("FETCH is already defined.");
}
return previousSort;
}
{code}
Why does method validateAndGetChildSort check the fetch of previousSort? In my
opinion, this validation makes no sense if user desire to continuously fetch or
limit.
was (Author: nicholasjiang):
[~twalthr],[~dwysakowicz],
{code:java}
private SortQueryOperation validateAndGetChildSort(QueryOperation child,
PostResolverFactory postResolverFactory) {
final SortQueryOperation previousSort;
if (child instanceof SortQueryOperation) {
previousSort = (SortQueryOperation) child;
} else {
previousSort = (SortQueryOperation) createSort(Collections.emptyList(),
child, postResolverFactory);
}
if ((previousSort).getFetch() != -1) {
throw new ValidationException("FETCH is already defined.");
}
return previousSort;
}
{code}
Why does method validateAndGetChildSort check the fetch of previousSort? In my
opinion, this validation has no sense if user want to continuously fetch or
limit.
> It doesn't support to call Table.limit() continuously
> -----------------------------------------------------
>
> Key: FLINK-19038
> URL: https://issues.apache.org/jira/browse/FLINK-19038
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / API
> Affects Versions: 1.12.0
> Reporter: Dian Fu
> Assignee: Nicholas Jiang
> Priority: Major
> Fix For: 1.12.0
>
>
> For example, table.limit(3).limit(2) will failed with "FETCH is already
> defined."
> {code}
> org.apache.flink.table.api.ValidationException: FETCH is already defined.
> at
> org.apache.flink.table.operations.utils.SortOperationFactory.validateAndGetChildSort(SortOperationFactory.java:125)
> at
> org.apache.flink.table.operations.utils.SortOperationFactory.createLimitWithFetch(SortOperationFactory.java:105)
> at
> org.apache.flink.table.operations.utils.OperationTreeBuilder.limitWithFetch(OperationTreeBuilder.java:418)
> {code}
> However, as we support to call table.limit() without specifying the order, I
> guess this should be a valid usage and should be allowed.
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