zhengzengprc commented on a change in pull request #3039:
URL: https://github.com/apache/iceberg/pull/3039#discussion_r700639354
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File path: core/src/main/java/org/apache/iceberg/util/SnapshotUtil.java
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@@ -65,12 +65,16 @@ 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 the timestamp.
+ * @return null if there is no current snapshot in the table, else the
oldest Snapshot after the timestamp.
Review comment:
Hello @kbendick , thanks for bringing up the questions. That's a really
good question for the strictly greater than the passed in timestamp.
Honestly, I don't have a strong reason use strictly greater. IMO, the
function should include the "equal" case while user passes in the existing
timestamp that exists.
From the sample:
let's say we have snapshot with time series: 10,20,30,40,50
Current snapshot will be with timestamp 50.
The input timestamp is 30.
I think 30 should be the expected answer from the function calls.
The boolean logic should include the "=" case,
`while (current.parentId() != null &&
table.snapshot(current.parentId()).timestampMillis() >= timestamp)`
I try to reach @SreeramGarlapati to see if we have a strong reason put
"strictly greater", if I miss something here. But I am still waiting input from
Sreeram.
@SreeramGarlapati do you know anything behind the scene that we put the
"strictly greater"?
Personally I prefer the ">=" approach.
Beside the reason of `as-of-timestamp`. I think the function return should
be consistent, let's take back above example to go through current
implementation:
Case 1:
Snapshot with time series: 10,20,30,40,50
Current timestamp: 50
Input timestamp: 50
Function return 50
Case 2:
Snapshot with time series: 10,20,30,40,50
Current timestamp: 50
Input timestamp: 40
Function return 50
The result looks like inconsistent to me, since case 1 returns inclusive 50,
but case 2 not. IMO, these logic should be consistent with each other
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