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The following commit(s) were added to refs/heads/master by this push:
new 49feffff1b Add comment about double-close in
ColumnSelectorColumnIndexSelector. (#12735)
49feffff1b is described below
commit 49feffff1bd72781e2ca4c27312aedaf50b0510b
Author: Gian Merlino <[email protected]>
AuthorDate: Wed Jul 6 00:50:35 2022 -0700
Add comment about double-close in ColumnSelectorColumnIndexSelector.
(#12735)
---
.../druid/segment/ColumnSelectorColumnIndexSelector.java | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git
a/processing/src/main/java/org/apache/druid/segment/ColumnSelectorColumnIndexSelector.java
b/processing/src/main/java/org/apache/druid/segment/ColumnSelectorColumnIndexSelector.java
index f87c4bffec..6b7e0b666b 100644
---
a/processing/src/main/java/org/apache/druid/segment/ColumnSelectorColumnIndexSelector.java
+++
b/processing/src/main/java/org/apache/druid/segment/ColumnSelectorColumnIndexSelector.java
@@ -29,6 +29,7 @@ import org.apache.druid.segment.column.NumericColumn;
import javax.annotation.Nullable;
/**
+ *
*/
public class ColumnSelectorColumnIndexSelector implements ColumnIndexSelector
{
@@ -50,7 +51,17 @@ public class ColumnSelectorColumnIndexSelector implements
ColumnIndexSelector
@Override
public int getNumRows()
{
- try (final NumericColumn column = (NumericColumn)
columnSelector.getColumnHolder(ColumnHolder.TIME_COLUMN_NAME).getColumn()) {
+ // This closes the __time column, which may initially seem like good
behavior, but in reality leads to a
+ // double-close when columnSelector is a ColumnCache (because all columns
from a ColumnCache are closed when
+ // the cache itself is closed). We're closing it here anyway, however, for
two reasons:
+ //
+ // 1) Sometimes, columnSelector is
DeprecatedQueryableIndexColumnSelector, not ColumnCache, and so the close
+ // here is important.
+ // 2) Double-close is OK for the __time column when this method is
expected to be used: the __time column is
+ // expected to be a ColumnarLongs, which is safe to double-close.
+
+ try (final NumericColumn column = (NumericColumn)
columnSelector.getColumnHolder(ColumnHolder.TIME_COLUMN_NAME)
+
.getColumn()) {
return column.length();
}
}
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