This example demonstrates simple queries on a region.
In this example, two servers host a single partitioned region with entries that represent employee information. The example does queries through the API and presents example queries to be invoked through the
gfsh command-line interface.
This example assumes that Java and Geode are installed.
geode-examples/queries to be the current working directory. Each step in this example specifies paths relative to that directory.
Build the example (with the
$ ../gradlew build
Run a script that starts a locator and two servers, and then creates the
$ ../gradlew start
Run the example to populate
example-region with employee information, print out the region information, and then programmatically invoke three queries, printing the results of each query.
$ ../gradlew run
gfshcommands to query the region
gfsh can also be used to issue queries.
If you have not already installed Geode, the build step will have installed a
gfsh executable for you at a path relative to the current working directory within a versioned directory:
You can use this relative path to invoke gfsh by substituting the appropriate
gfsh and connect to the cluster:
$ gfsh ... gfsh>connect --locator=127.0.0.1
The quantity of entries may be observed with
gfsh>describe region --name=example-region
Here are some
gfsh queries to try on the
Query for all entries in the region:
gfsh>query --query="select * from /example-region"
Query for the
gfsh>query --query="SELECT x.email FROM /example-region x"
Query for all entries that have a
lastName field that starts with the letter ‘C’:
gfsh>query --query="SELECT DISTINCT * FROM /example-region x WHERE x.lastName.startsWith('C')"
Shut down the cluster:
$ ../gradlew stop
If desired, clean up the generated directories containing logs:
$ ../gradlew cleanServer