Question 1

How do I use CQEngine with Spring Boot?

Accepted Answer

Integrate CQEngine by creating IndexedCollection beans and defining attributes for your entities. There's no out-of-the-box starter, so you'll need to manage configuration manually, but it works seamlessly with Java collections in Spring contexts.

Question 2

CQEngine vs Java Streams for filtering collections?

Accepted Answer

CQEngine outperforms Java Streams by orders of magnitude for large datasets due to indexing, reducing time complexity from O(n) to O(1) for indexed queries. Use Streams for simple transformations, but CQEngine for high-performance querying.

Question 3

How to handle null values in CQEngine attributes?

Accepted Answer

Use SimpleNullableAttribute or MultiValueNullableAttribute to properly handle null values, as non-nullable attributes can throw NullPointerException. The README warns about this and recommends nullable attributes for uncertain data.

Question 4

Does CQEngine support full-text search like Lucene?

Accepted Answer

CQEngine supports string matching via indexes like SuffixTree for contains or endsWith queries, but it lacks advanced full-text features such as stemming or relevance scoring. For complex text search, consider integrating with Lucene or Elasticsearch.

Question 5

How to persist CQEngine collections to a database?

Accepted Answer

CQEngine itself handles on-heap, off-heap, or disk persistence, but for database storage, you'd need to sync data manually or use it as a cache layer. The README shows integration with ORMs for querying database-loaded collections.

Question 6

What's the performance impact of off-heap persistence?

Accepted Answer

Off-heap persistence reduces Java heap usage but may introduce higher latency compared to on-heap, as data is stored in native memory. The README notes it's slower than on-heap but faster than disk, suitable for large datasets.

CQEngine

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