Executing Index Queries
Index queries work over distributed indexes and retrieve cache entries that match the specified query. IndexQuery can be used if a low amount of data
matches filtering criteria. For these cases, ScanQuery usage is not optimal.
// Create index by 2 fields (orgId, salary).
LinkedHashMap<String,String> fields = new LinkedHashMap<>();
fields.put("orgId", Integer.class.getName());
fields.put("salary", Integer.class.getName());
QueryEntity personEntity = new QueryEntity(Integer.class, Person.class)
.setFields(fields)
.setIndexes(Collections.singletonList(
new QueryIndex(Arrays.asList("orgId", "salary"), QueryIndexType.SORTED)
.setName("ORG_SALARY_IDX")
));
CacheConfiguration<Integer, Person> ccfg = new CacheConfiguration<Integer, Person>("entityCache")
.setQueryEntities(Collections.singletonList(personEntity));
IgniteCache<Integer, Person> cache = ignite.getOrCreateCache(ccfg);
// Find the persons who work in Organization 1.
QueryCursor<Cache.Entry<Integer, Person>> cursor = cache.query(
new IndexQuery<Integer, Person>(Person.class, "ORG_SALARY_IDX")
.setCriteria(eq("orgId", 1))
);Index query criteria are defined in the IndexQueryCriteriaBuilder. Criteria fields have to match the specified index.
For example, if there is an index defined with (A, B) set, then valid criteria sets are (A) and (A, B).
Criteria with the single (B) field will be executed without using an index because the field (B) is not a prefix set of the specified index fields,
and it’s impossible to build a narrow index range with it.
// Find the persons who work in Organization 1 and have salary more than 1,000.
QueryCursor<Cache.Entry<Integer, Person>> cursor = cache.query(
new IndexQuery<Integer, Person>(Person.class, "ORG_SALARY_IDX")
.setCriteria(eq("orgId", 1), gt("salary", 1000))
);The index name is an optional parameter. In this case, GridGain tries to figure out the index by itself using specified criteria fields.
// GridGain finds suitable index "ORG_SALARY_IDX" by specified criterion field "orgId".
QueryCursor<Cache.Entry<Integer, Person>> cursor = cache.query(
new IndexQuery<Integer, Person>(Person.class)
.setCriteria(eq("orgId", 1))
);For the empty criteria list, a full table scan is performed.
Additional filtering
IndexQuery also supports an optional predicate, the same as ScanQuery has. It’s suitable for additional cache entry
filtering. For example, it may contain some logic or the "OR" operations.
// Find the persons who work in Organization 1 and whose name contains 'Vasya'.
QueryCursor<Cache.Entry<Integer, Person>> cursor = cache.query(
new IndexQuery<Integer, Person>(Person.class)
.setCriteria(eq("orgId", 1))
.setFilter((k, v) -> v.getName().contains("Vasya"))
);© 2024 GridGain Systems, Inc. All Rights Reserved. Privacy Policy | Legal Notices. GridGain® is a registered trademark of GridGain Systems, Inc.
Apache, Apache Ignite, the Apache feather and the Apache Ignite logo are either registered trademarks or trademarks of The Apache Software Foundation.