Github user zsxwing commented on a diff in the pull request:
https://github.com/apache/spark/pull/15852#discussion_r88357129
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/CompactibleFileStreamLog.scala
---
@@ -63,7 +63,60 @@ abstract class CompactibleFileStreamLog[T <: AnyRef :
ClassTag](
protected def isDeletingExpiredLog: Boolean
- protected def compactInterval: Int
+ protected def defaultCompactInterval: Int
+
+ protected final lazy val compactInterval: Int = {
+ // SPARK-18187: "compactInterval" can be set by user via
defaultCompactInterval.
+ // If there are existing log entries, then we should ensure a
compatible compactInterval
+ // is used, irrespective of the defaultCompactInterval. There are
three cases:
+ //
+ // 1. If there is no '.compact' file, we can use the default setting
directly.
+ // 2. If there are two or more '.compact' files, we use the interval
of patch id suffix with
+ // '.compact' as compactInterval. It is unclear whether this case will
ever happen in the
+ // current code, since only the latest '.compact' file is retained
i.e., other are garbage
+ // collected.
+ // 3. If there is only one '.compact' file, then we must find a
compact interval
+ // that is compatible with (i.e., a divisor of) the previous compact
file, and that
+ // faithfully tries to represent the revised default compact interval
i.e., is at least
+ // is large if possible.
+ // e.g., if defaultCompactInterval is 5 (and previous compact interval
could have
+ // been any 2,3,4,6,12), then a log could be: 11.compact, 12, 13, in
which case
+ // will ensure that the new compactInterval = 6 > 5 and (11 + 1) % 6
== 0
+ val compactibleBatchIds = fileManager.list(metadataPath,
batchFilesFilter)
+ .filter(f =>
f.getPath.toString.endsWith(CompactibleFileStreamLog.COMPACT_FILE_SUFFIX))
+ .map(f => pathToBatchId(f.getPath))
+ .sorted
+ .reverse
+
+ // Case 1
+ var interval = defaultCompactInterval
+ if (compactibleBatchIds.length >= 2) {
+ // Case 2
+ val latestCompactBatchId = compactibleBatchIds(0)
+ val previousCompactBatchId = compactibleBatchIds(1)
+ interval = (latestCompactBatchId - previousCompactBatchId).toInt
+ logInfo(s"Compact interval case 2 = $interval")
+ } else if (compactibleBatchIds.length == 1) {
+ // Case 3
+ val latestCompactBatchId = compactibleBatchIds(0).toInt
+ if (latestCompactBatchId + 1 <= defaultCompactInterval) {
+ interval = latestCompactBatchId + 1
+ } else if (defaultCompactInterval < (latestCompactBatchId + 1) / 2) {
+ // Find the first divisor >= default compact interval
+ def properDivisors(n: Int, min: Int) =
+ (min to n/2).filter(i => n % i == 0) :+ n
+
--- End diff --
I would use the following codes to avoid generating the real number
sequence:
```Scala
def properDivisors(n: Int, min: Int) = (min to n/2).view.filter(n % _ == 0)
:+ n
interval = properDivisors(latestCompactBatchId + 1,
defaultCompactInterval).head
```
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