Step 2 - Query all the employees from a state

You can use the new global secondary index to query the table. If you use only the state, the query does not use the sort key attribute. However, if the query has a value for the second parameter, the code uses the GSI_3_SK attribute of the global secondary index, which holds the same value as the city_dept attribute, to query all the values that begin with the parameter value.

The following screenshot shows using composite key attributes to query by city and department. Using Composite key attributes to query by city and department

We can perform this same query in a Python script. This snippet shows how a script can take two input parameters (shown as value1 and value2) and craft a query against the GSI_3 global secondary index.

if value2 == "-":
  ke = Key('GSI_3_PK').eq("state#{}".format(value1))
else:
  ke = Key('GSI_3_PK').eq("state#{}".format(value1)) & Key('GSI_3_SK').begins_with(value2)

response = table.query(
  IndexName='GSI_3',
  KeyConditionExpression=ke
  )

Run the following Python script to query global secondary index GSI_3 for all employees in the state of Texas.

python query_city_dept.py employees TX

The result should look similar to the following.

List of employees . State: TX
    Name: Bree Gershom. City: Austin. Dept: Development
    Name: Lida Flescher. City: Austin. Dept: Development
    Name: Tristam Mole. City: Austin. Dept: Development
    Name: Malinde Spellman. City: Austin. Dept: Development
    Name: Giovanni Goutcher. City: Austin. Dept: Development
  ...
  Name: Cullie Sheehy. City: San Antonio. Dept: Support
  Name: Ari Wilstead. City: San Antonio. Dept: Support
  Name: Odella Kringe. City: San Antonio. Dept: Support
Total of employees: 197. Execution time: 0.238062143326 seconds