Apache Ignite ScanQuery on local node returns empty result

Question

I have one server node and one client node. I create cache on the client node and put some objects there

CacheConfiguration<String, T> cfg = new CacheConfiguration<>();
cfg.setAtomicityMode(CacheAtomicityMode.TRANSACTIONAL);
cfg.setName("myCacheName");
cfg.setCacheMode(CacheMode.REPLICATED);
cfg.setWriteSynchronizationMode(CacheWriteSynchronizationMode.FULL_SYNC);
cfg.setRebalanceMode(CacheRebalanceMode.SYNC);

NearCacheConfiguration<String, T> nearCacheCfg = new NearCacheConfiguration<>();
nearCacheCfg.setNearEvictionPolicyFactory(new LruEvictionPolicyFactory<>(100_000));
cfg.setNearConfiguration(nearCacheCfg);
cache = ignite.getOrCreateCache(cfg);

Then I try to get all entries with ScanQuery and setLocal(true) option from the client node, but I get an empty result

try (var cursor = cache.query(new ScanQuery<>(null).setLocal(true))) {
    return cursor.getAll().stream()
        .map(Cache.Entry::getValue)
        .toList();
}

If I do this without setLocal(true) option, it works well, and I get all entiries.

If I use cache.localEntries(ALL).iterator(), I get all enitries too.

What's wrong with ScanQuery?

Answer 1

• Client nodes do not hold any data
• The data is stored on server nodes (no matter if you put it from client node or not)

Therefore, local scan query always returns empty results on client node.

Local scan query makes sense on server nodes only (e.g. within a Compute task).