Creating, Listing and Removing Indexes

The GemFire QueryService API provides methods to create, list and remove the index. You can also use gfsh command-line interface to create, list and remove indexes, and use cache.xml to create an index.

Creating Indexes

Indexes can be created programmatically, by using the gfsh command line interface or by using cache.xml.

To create an index, use one of the following QueryService methods:

createIndex. Creates the default type of index, a range index. Use this type of index if you will be writing queries that will be doing any kind of comparison operation besides an equality comparison.
createKeyIndex. Creates a key index. See Creating Key Indexes for more information.
createHashIndex. Creates a hash index. See Creating Hash Indexes for more information.
createDefinedIndexes. Creates multiple indexes that were previously defined using defineIndex. See Creating Multiple Indexes at Once for more information.

The following sections provide examples of index creation:

Using gfsh:

gfsh> create index --name=myIndex --expression=status --region=/exampleRegion
gfsh> create index --name=myKeyIndex --type=key --expression=id --region=/exampleRegion
gfsh> create index --name=myHashIndex --type=hash --expression=mktValue --region=/exampleRegion

See Index Commands for more examples.

Using Java API:

QueryService qs = cache.getQueryService();
 qs.createIndex("myIndex", "status", "/exampleRegion");
 qs.createKeyIndex("myKeyIndex", "id", "/exampleRegion");
 qs.createHashIndex("myHashIndex", "mktValue", "/exampleRegion");

Using cache.xml:

<region name=exampleRegion>
 <region-attributes . . . >
 </region-attributes>
 <index name="myIndex" from-clause="/exampleRegion" expression="status"/>
 <index name="myKeyIndex" from-clause="/exampleRegion" expression="id" key-index="true"/>
 <index name="myHashIndex" from-clause="/exampleRegion p" expression="p.mktValue" type="hash"/>
 ...
</region>

Note: If you do not specify the type of index in cache.xml, the type defaults to "range".

Listing Indexes

To retrieve a list of indexes from the cache or region, use the QueryService.getIndexes method or the gfsh command line interface.

Using gfsh:

gfsh> list indexes
gfsh> list indexes --with-stats

Using Java API:

QueryService qs = cache.getQueryService();
 qs.getIndexes(); //returns a collection of all indexes in the cache
 qs.getIndexes(exampleRegion); //returns a collection of all indexes in exampleRegion
 qs.getIndexes(exampleRegion, myKeyIndex); //returns the index named myKeyIndex from the exampleRegion

Removing Indexes

To remove an index or all indexes from the cache or region, use the QueryService.removeIndexes method or the gfsh command line interface.

Using gfsh:

gfsh> destroy index
gfsh> destroy index --name=myIndex
gfsh> destroy index --region=/exampleRegion

Using Java API:

QueryService qs = cache.getQueryService();
 qs.removeIndexes(); //removes all indexes from the cache
 qs.removeIndexes(myKeyIndex); //removes the index named myKeyIndex
 qs.removeIndexes(exampleRegion); //removes all indexes from the exampleRegion