tkalkirill commented on code in PR #2019:
URL: https://github.com/apache/ignite-3/pull/2019#discussion_r1187262290
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modules/metastorage/src/main/java/org/apache/ignite/internal/metastorage/server/persistence/RocksDbKeyValueStorage.java:
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@@ -975,30 +1020,104 @@ private boolean addToBatchForRemoval(WriteBatch batch,
byte[] key, long curRev,
}
/**
- * Compacts all entries by the given key, removing all previous revisions
and deleting the last entry if it is a tombstone.
+ * Compacts all entries by the given key, removing revision that are no
longer needed.
+ * Last entry with a revision lesser or equal to the {@code
minRevisionToKeep} and all consecutive entries will be preserved.
+ * If the first entry to keep is a tombstone, it will be removed.
+ * Example:
+ * <pre>
+ * Example 1:
+ * put entry1: revision 5
+ * put entry2: revision 7
+ *
+ * do compaction: revision 6
+ *
+ * entry1: exists
+ * entry2: exists
+ *
+ * Example 2:
+ * put entry1: revision 5
+ * put entry2: revision 7
+ *
+ * do compaction: revision 7
+ *
+ * entry1: doesn't exist
+ * entry2: exists
+ * </pre>
*
* @param batch Write batch.
* @param key Target key.
* @param revs Revisions.
+ * @param minRevisionToKeep Minimum revision that should be kept.
* @throws RocksDBException If failed.
*/
- private void compactForKey(WriteBatch batch, byte[] key, long[] revs)
throws RocksDBException {
- long lastRev = lastRevision(revs);
+ private void compactForKey(WriteBatch batch, byte[] key, long[] revs, long
minRevisionToKeep) throws RocksDBException {
+ if (revs.length < 2) {
+ // If we have less than two revisions, there is no point in
compaction.
+ return;
+ }
+
+ // Index of the first revision we will be keeping in the array of
revisions.
+ int idxToKeepFrom = 0;
+
+ // Whether there is an entry with the minRevisionToKeep.
+ boolean hasMinRevision = false;
+
+ // Traverse revisions, looking for the first revision that needs to be
kept.
+ for (long rev : revs) {
+ if (rev >= minRevisionToKeep) {
+ if (rev == minRevisionToKeep) {
+ hasMinRevision = true;
+ }
+ break;
+ }
+
+ idxToKeepFrom++;
+ }
Review Comment:
It's just a "can it be done?" question.
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