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https://issues.apache.org/jira/browse/AURORA-1861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15750491#comment-15750491
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David McLaughlin commented on AURORA-1861:
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The ability to process the fields without having to restore the H2 database is
probably more useful when writing scripts against backups in languages like
Python/Go/any language with a Thrift compiler. I know we do some of this at
Twitter. We could probably provide a JVM utility that converts a DB Script
backup into the old fully hydrated one though... otherwise I don't know how
we'd ever be able to turn DbTaskStore on at any scale.
> Remove duplicate Snapshot fields for DB stores
> ----------------------------------------------
>
> Key: AURORA-1861
> URL: https://issues.apache.org/jira/browse/AURORA-1861
> Project: Aurora
> Issue Type: Task
> Components: Scheduler
> Reporter: David McLaughlin
>
> Currently we double-write any DB-backed stores into a Snapshot struct when
> creating a Snapshot. This inflates the size of the Snapshot, which is already
> a problem for large production clusters (see AURORA-74).
> Example for LockStore from
> https://github.com/apache/aurora/blob/master/src/main/java/org/apache/aurora/scheduler/storage/log/SnapshotStoreImpl.java:
> {code}
> new SnapshotField() {
> // It's important for locks to be replayed first, since there are
> relations that expect
> // references to be valid on insertion.
> @Override
> public void saveToSnapshot(MutableStoreProvider store, Snapshot
> snapshot) {
>
> snapshot.setLocks(ILock.toBuildersSet(store.getLockStore().fetchLocks()));
> }
> @Override
> public void restoreFromSnapshot(MutableStoreProvider store, Snapshot
> snapshot) {
> if (hasDbSnapshot(snapshot)) {
> LOG.info("Deferring lock restore to dbsnapshot");
> return;
> }
> store.getLockStore().deleteLocks();
> if (snapshot.isSetLocks()) {
> for (Lock lock : snapshot.getLocks()) {
> store.getLockStore().saveLock(ILock.build(lock));
> }
> }
> }
> },
> {code}
> The saveToSnapshot here is totally redundant as the entire H2 database is
> dumped into the dbScript field.
> Note: one major side-effect here is if anyone is trying to read these
> snapshots and utilize the data outside of Java - they'll lose the ability to
> process the data without being able to apply the DB script.
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