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JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
HCL Informix® JSON compatibility
The Informix® JSON Compatibility Guide describes how applications that use the popular JSON-oriented query language created by MongoDB can interact with data stored in HCL Informix.
JSON data sharding
You can shard data with HCL Informix®. Documents from a collection or rows from a table can be sharded across a cluster of database servers, reducing the number of documents or rows and the size of the index for the database of each server. When you shard data across database servers, you also distribute performance across hardware. As your database grows in size, you can scale up by adding more shard servers to your shard cluster.
Preparing shard servers
You must prepare shard servers before you can shard data.

JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
- HCL Informix® JSON compatibility
  The Informix® JSON Compatibility Guide describes how applications that use the popular JSON-oriented query language created by MongoDB can interact with data stored in HCL Informix.
  - About the Informix® JSON compatibility
    You can combine relational and JSON data into a single query by using the Informix® JSON compatibility features.
  - Wire listener
    The wire listener is a mid-tier gateway server that enables communication between MongoDB, REST API, and MQTT clients and the Informix® database server.
  - JSON data sharding
    You can shard data with HCL Informix®. Documents from a collection or rows from a table can be sharded across a cluster of database servers, reducing the number of documents or rows and the size of the index for the database of each server. When you shard data across database servers, you also distribute performance across hardware. As your database grows in size, you can scale up by adding more shard servers to your shard cluster.
    - Preparing shard servers
      You must prepare shard servers before you can shard data.
    - Shard-cluster definitions for distributing data
      A cluster of shard servers uses a definition to distribute data across shard servers.
    - Shard cluster management
      You can display information about shard cluster participants and about the shard cache on each shard server. You can add or remove shard servers from a shard cluster.
  - MongoDB API and commands
    The Informix® support for MongoDB application programming interfaces and commands are described here.
  - REST API
    The REST API provides a method for accessing JSON collections in Informix® and provides driverless access to your data.
  - MQTT protocol
    The MQTT protocol provides a method for loading JSON data in Informix®.
  - Manage time series through the wire listener
    You can create and manage time series through the wire listener. You interact with time series data through a virtual table.
  - Troubleshooting Informix® JSON compatibility
    Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter with Informix® JSON compatibility.

Preparing shard servers

You must prepare shard servers before you can shard data.

Procedure

To set up shard servers:

On each shard server, set the SHARD_ID configuration parameter to a positive integer value that is unique in the shard cluster by running the following command:
```
onmode -wf SHARD_ID=unique_positive_integer
```
If the SHARD_ID configuration parameter is already set to a positive integer, you can change the value by editing the onconfig file and then restarting the database server. You can also set the SHARD_MEM configuration parameter to customize the number of memory pools that are used during shard queries.
Specify trusted hosts information for all shard servers.
On each shard server, run the SQL administration API task() or admin() function with the cdr add trustedhost argument and include the appropriate host values for all the other shard servers. You must be a Database Server Administrator (DBSA) to run these functions.
On each shard server, edit the wire listener configuration file:
1. Set the sharding.enable parameter to true.
2. Set the sharding.query.parallel.enable parameter to true.
3. Set the update.client.strategy parameter to deleteInsert.
4. If you want to allow shard key field values to be updated, set the update.mode parameter to client. If you do not want to allow the updating of shard key field values, you can leave the setting of the update.mode parameter as the default value of mixed.
5. Set the USER attribute in the url parameter to a user who has the REPLICATION privilege. If you created a database server instance during installation, the ifxjson user, who has the REPLICATION privilege, is automatically set as the value of the USER attribute. Otherwise, see Configuring the wire listener for the first time for instructions.
On each shard server, restart the wire listener.

What to do next

When applications connect to shard servers, enable sharded queries to run against data across all shard servers by setting the USE_SHARDING session environment variable:

SET ENVIRONMENT USE_SHARDING ON;