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https://issues.apache.org/jira/browse/DRILL-2288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14990527#comment-14990527
]
ASF GitHub Bot commented on DRILL-2288:
---------------------------------------
Github user dsbos commented on a diff in the pull request:
https://github.com/apache/drill/pull/228#discussion_r43946374
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/vector/complex/fn/JsonReader.java
---
@@ -93,13 +93,15 @@ public void ensureAtLeastOneField(ComplexWriter writer)
{
if (!atLeastOneWrite) {
// if we had no columns, create one empty one so we can return some
data for count purposes.
SchemaPath sp = columns.get(0);
- PathSegment root = sp.getRootSegment();
+ PathSegment fieldPath = sp.getRootSegment();
BaseWriter.MapWriter fieldWriter = writer.rootAsMap();
- while (root.getChild() != null && !root.getChild().isArray()) {
- fieldWriter = fieldWriter.map(root.getNameSegment().getPath());
- root = root.getChild();
+ while (fieldPath.getChild() != null && !
fieldPath.getChild().isArray()) {
+ fieldWriter =
fieldWriter.map(fieldPath.getNameSegment().getPath());
+ fieldPath = fieldPath.getChild();
+ }
+ if (fieldWriter.isEmptyMap()) {
--- End diff --
Another question:
> Basically change:
>
> if (!atLeastOneWrite) {
>
> to
>
> if (fieldWriter.isEmptyMap()) {
Would that field writer be the writer from writer.rootAsMap(), or does the
code still need the loop and its traversal?
(It seems that changing the "if (!atLeastOneWrite)" to (the simplified
equivalent) of "if (true)" (and keeping the loop) work work, but I don't know
what the minimum fix is (i.e., exactly how much of that loop and traversal is
needed).)
> ScanBatch violates IterOutcome protocol for zero-row sources [was: missing
> JDBC metadata (schema) for 0-row results...]
> -----------------------------------------------------------------------------------------------------------------------
>
> Key: DRILL-2288
> URL: https://issues.apache.org/jira/browse/DRILL-2288
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - Information Schema
> Reporter: Daniel Barclay (Drill)
> Assignee: Daniel Barclay (Drill)
> Fix For: 1.3.0
>
> Attachments: Drill2288NoResultSetMetadataWhenZeroRowsTest.java
>
>
> The ResultSetMetaData object from getMetadata() of a ResultSet is not set up
> (getColumnCount() returns zero, and trying to access any other metadata
> throws IndexOutOfBoundsException) for a result set with zero rows, at least
> for one from DatabaseMetaData.getColumns(...).
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