rdblue commented on a change in pull request #3039:
URL: https://github.com/apache/iceberg/pull/3039#discussion_r753578980
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File path: core/src/main/java/org/apache/iceberg/util/SnapshotUtil.java
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@@ -65,12 +65,18 @@ public static boolean ancestorOf(Table table, long
snapshotId, long ancestorSnap
}
/**
- * Traverses the history of the table's current snapshot and finds the
oldest Snapshot.
- * @return null if there is no current snapshot in the table, else the
oldest Snapshot.
+ * Traverses the history of the table's current snapshot
+ * and finds the oldest Snapshot after or equal to the timestamp in
milliseconds.
+ * @return null if there is no current snapshot in the table,
+ * else the oldest Snapshot after or equal to the timestamp in milliseconds.
*/
- public static Snapshot oldestSnapshot(Table table) {
+ public static Snapshot oldestSnapshot(Table table, long timestampMillis) {
Review comment:
To simplify the work here, I updated how `SnapshotUtil` works in #3259.
That adds a way to create an `Iterable<Snapshot>` of the ancestors given some
starting snapshot, `SnapshotUtil.ancestorsOf`. That should make implementing
`oldestAncestorAfter` cleaner:
```java
/**
* Traverses the history of the table's current snapshot and finds the
first snapshot after the given timestamp.
*
* @param table a table
* @param timestampMillis a timestamp in milliseconds
* @return the first snapshot after the given timestamp, or null if the
current snapshot is older than the timestamp
* @throws IllegalStateException if the first ancestor after the given
time can't be determined
*/
public static Snapshot oldestAncestorAfter(Table table, long
timestampMillis) {
if (table.currentSnapshot() == null) {
// there are no snapshots or ancestors
return null;
}
Snapshot lastSnapshot = null;
for (Snapshot snapshot : currentAncestors(table)) {
if (snapshot.timestampMillis() <= timestampMillis) {
return lastSnapshot;
}
lastSnapshot = snapshot;
}
if (lastSnapshot != null && lastSnapshot.parentId() == null) {
// this is the first snapshot in the table, return it
return lastSnapshot;
}
throw new IllegalStateException(
"Cannot find snapshot older than " +
DateTimeUtil.formatTimestampMillis(timestampMillis));
}
```
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