[GitHub] [iceberg] namrathamyske commented on a diff in pull request #5364: Core, API: Support scanning from a branch along with time travel

[GitBox <gi...@apache.org>]

namrathamyske commented on code in PR #5364:
URL: https://github.com/apache/iceberg/pull/5364#discussion_r940689479


##########
core/src/main/java/org/apache/iceberg/util/SnapshotUtil.java:
##########
@@ -322,6 +323,39 @@ public static long snapshotIdAsOfTime(Table table, long timestampMillis) {
     return snapshotId;
   }
 
+  /**
+   * Returns the ID of the most recent snapshot on the given branch
+   * as of the given time in milliseconds
+   *
+   * @param table a {@link Table}
+   * @param branch a {@link String}
+   * @param timestampMillis the timestamp in millis since the Unix epoch
+   * @return the snapshot ID
+   * @throws IllegalArgumentException when no snapshot is found in the table, on the given branch
+   * older than the timestamp
+   */
+  public static long snapshotIdAsOfTime(Table table, String branch, long timestampMillis) {
+    SnapshotRef ref = table.refs().get(branch);
+    Preconditions.checkArgument(ref != null, "Branch %s does not exist", branch);
+    Preconditions.checkArgument(ref.isBranch(), "Ref %s is a tag, not a branch", branch);
+    Long snapshotId = null;
+    long minimumTimeDifference = Long.MAX_VALUE;
+    for (Snapshot snapshot : ancestorsOf(ref.snapshotId(), table::snapshot)) {
+      if (snapshot.timestampMillis() <= timestampMillis) {
+        if (timestampMillis - snapshot.timestampMillis() <= minimumTimeDifference) {
+          minimumTimeDifference = timestampMillis - snapshot.timestampMillis();
+          snapshotId = snapshot.snapshotId();
+        }
+      }
+    }
+
+    Preconditions.checkArgument(snapshotId != null,
+        "Cannot find a snapshot older than %s on branch %s",
+        DateTimeUtil.formatTimestampMillis(timestampMillis), branch);
+
+    return snapshotId;
+  }
+

Review Comment:
   Can we make reuse `snapshotIdAsOfTime` here? We will also need to make necessary changes for this function to accept a branch.



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