OAK Query aborted

Every AEM developer faced with below exception which means that we are exceeded the limit of nodes for reading:

java.lang.UnsupportedOperationException: The query read or traversed more than 100000 nodes. To avoid affecting other tasks, processing was stopped.
	at org.apache.jackrabbit.oak.query.FilterIterators.checkReadLimit(FilterIterators.java:70)
	at org.apache.jackrabbit.oak.plugins.index.Cursors.checkReadLimit(Cursors.java:67)
	at org.apache.jackrabbit.oak.plugins.index.lucene.LucenePropertyIndex$LucenePathCursor$1.next(LucenePropertyIndex.java:1730)
	at org.apache.jackrabbit.oak.plugins.index.lucene.LucenePropertyIndex$LucenePathCursor$1.next(LucenePropertyIndex.java:1711)
	at com.google.common.collect.Iterators$7.computeNext(Iterators.java:646)
	at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
	at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
	at org.apache.jackrabbit.oak.plugins.index.Cursors$PathCursor.hasNext(Cursors.java:216)
	at org.apache.jackrabbit.oak.plugins.index.lucene.LucenePropertyIndex$LucenePathCursor.hasNext(LucenePropertyIndex.java:1751)
	at org.apache.jackrabbit.oak.query.ast.SelectorImpl.next(SelectorImpl.java:432)
	at org.apache.jackrabbit.oak.query.QueryImpl$RowIterator.fetchNext(QueryImpl.java:824)
	at org.apache.jackrabbit.oak.query.QueryImpl$RowIterator.hasNext(QueryImpl.java:851)
	at org.apache.jackrabbit.oak.jcr.query.QueryResultImpl$1.fetch(QueryResultImpl.java:98)

In this situation, we can:

  • define the oak index for a query
  • try to redesign taxonomy of a repository or structure if it might be improved
  • update oak indexes to cover the query
  • use oak:Unstructured instead of nt:unstructured and sling:Folder instead of sling:OrderedFolder in a case where an order is not required
  • etc.

During the development, if we want to skip this error for a while we can increase LimitReads and LimitInMemory parameters for OAK Query Engine:

  1. navigate to  QueryEngineSettings
  2.  increase selected parameters:
  3. this is for development stage only, please, do not push this on production

Links to resources for help:

  1. Oak Index Definition Generator

  2. Best Practices for Queries and Indexing

Split Apache OAK stores

Split Apache OAK stores


One of big projects drawbacks is a size of Apache OAK which is growing very fast due to big amount of assets , binary files, background processes which are care about repository data consistency, updates and so on. Of cause we can use compaction every week but there is exists another approach – split segment and blob store out of Tar files (which is an OOTB store implementation). One of the available option is to split NodeStore and BlobStore. More about BlobStore you can read here – click. Continue reading “Split Apache OAK stores”