A feature of the in-memory data store provided by Tanzu GemFire is the ability to query the data.
Queries are specified in the OQL language. OQL syntax and semantics are similar to SQL. See the Pivotal GemFire section on Querying for details on the OQL language.
Queries can be initiated through an API call of
or through the gfsh
All queries are executed on the servers holding the region data. Take care not to overwhelm the resources when specifying queries. For example,
SELECT * FROM /trades
returns all values in the
For a large region (millions of entries),
the resources of server processing and memory needed to gather and return
the data set may be considerable.
Consider the processing and data set size when specifying queries.
There are a set of example apps within the GitHub
query example introduces querying.
README.md file contains instructions on how to run the example.
This stripped-down app contains the minimum code necessary to run
in a local development environment with a GemFire cluster.