Search Group Data in Cache with SQL

Note

This feature is only available in NCache Enterprise Edition.

NCache provides object queries through which you use a criteria given in a query to search result sets. To retrieve the data according to your specified criteria, NCache provides you with an extension of SQL.

A special keyword $Group$ is used to specify that the condition under consideration uses group.A query with the searching criteria is executed using ExecuteReader.

ExecuteReader processes the query on the server side and then sends the result in chunks (as a dictionary containing keys and values) to the client in the tabular form to ICacheReader type of instance.

Prerequisites

Install the following NuGet package in your application:
- Enterprise: Alachisoft.NCache.SDK
Include the following namespaces in your application:
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
Make sure that the data being added is serializable.
For API details refer to: ICache, ICacheReader, QueryCommand, ExecuteReader
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-client</artifactId>
    <version>x.x.x</version>
</dependency>

Include the following packages in your application:
- import com.alachisoft.ncache.runtime.exceptions.*;
- import com.alachisoft.ncache.client.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
Make sure that the data being added is serializable.
For API details refer to: Cache, CacheReader, executeReader
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install and include the following module in your application:
- Enterprise: const ncache = require('ncache-client')
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
For API details refer to: Cache, executeReader.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install the NCache Python client by executing the following command:

# Enterprise Client
pip install ncache-client

Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
Import the NCache module in your application.
Cache must be running.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-scala-client</artifactId>
    <version>x.x.x</version>
</dependency>

Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
Import the following packages in your application:
- import com.alachisoft.ncache.scala.client.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Make sure that the data being added is serializable.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Warning

If the searched group is not in the cache, the query will be returned as Null.

Search for Group

Given a certain criteria, you can search for groups present in the cache with SQL queries. The following program searches for a group against a certain Customer ID through SQL query i.e. the group that the Customer ID belongs to.

try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class 
    string query = "SELECT $Group$ FROM FQN.Customer WHERE CustomerName = ?";

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);

    // Providing parameters for query
    queryCommand.Parameters.Add("CustomerName", "John Smith");

    // Executing QueryCommand through ICacheReader
    ICacheReader cacheReader = cache.SearchService.ExecuteReader(queryCommand);

    // Check if the result set is not empty
    if (cacheReader.FieldCount > 0)
    {
        while (cacheReader.Read())
        {
           // Perform operations
            string groupName = cacheReader.GetValue<string>(1);                   
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures 
        // Operation Timeout
        // Operation performed during state transfer    
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentException, ArgumentNullException
}

try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class
    String query = "SELECT $Group$ FROM FQN.Customer WHERE CustomerName = ?";

    // Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);

    // Providing parameters for query
    queryCommand.getParameters().put("CustomerName", "John Smith");

    // Executing QueryCommand through cacheReader
    CacheReader cacheReader = cache.getSearchService().executeReader(queryCommand);

    // Check if the result set is not empty
    if (cacheReader.getFieldCount() > 0)
    {
        while (cacheReader.read())
        {
            // Perform operations
            String groupName = cacheReader.getValue(1, String.class);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.getErrorCode() == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like NullPointerException or IllegalArgumentException
}

// This is an async method
try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class 
    var query = "SELECT $Group$ FROM FQN.Customer WHERE CustomerName = ?";

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);

    // Providing parameters for query
    let map = new Map();
    var parameters = map.set("CustomerName","John Smith");
    queryCommand.setParameters(parameters);

    // Executing QueryCommand
    var searchService = await this.cache.getSearchService();
    var cacheReader = await searchService.executeReader(queryCommand);

    // Check if the result set is not empty

    if (cacheReader.getFieldCount() > 0)
    {
        while (cacheReader.read())
        {
            // Perform operations
            var groupName = cacheReader.getValue(1);                   
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Pre-conditions: Cache is already connected
    # Items with groups exist in cache
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Search for items with group
    # Provide Fully Qualified Name(FQN) of your custom class

    # noinspection SqlNoDataSourceInspection
    query = "SELECT $Group$ FROM FQN.Customer WHERE customer_name = ?"

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)

    # Providing parameters for query
    parameters = {"customer_name": "John Smith"}
    query_command.set_parameters(parameters)

    # Executing QueryCommand
    search_service = cache.get_search_service()
    cache_reader = search_service.execute_reader(query_command)

    # Check if the result set is not empty

    if cache_reader.get_field_count() > 0:
        while cache_reader.read():
            # Perform operations
            group_name = cache_reader.get_value(str, 1)
    else:
        # None query result set retrieved
        print("Query result is None")
except Exception as exp:
    # Handle errors

try {
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class
    val query = "SELECT $Group$ FROM FQN.Customer WHERE CustomerName = ?"

    // Use QueryCommand for query execution
    val queryCommand = QueryCommand(query)

    // Providing parameters for query
    queryCommand.setParameters(Map("CustomerName" -> "John Smith"))

    // Executing QueryCommand through cacheReader
    val cacheReader = cache.getSearchService.executeReader(queryCommand)

    // Check if the result set is not empty
    if (cacheReader.getFieldCount > 0) {
      while (cacheReader.read) {
        // Perform operations
        val groupName = cacheReader.getValue(1, classOf[String])
      }
    } else {
      // Null query result set retrieved
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Search for Data in Groups

You can also search for cache items present in groups through SQL. The following program searches for Customer IDs present in a group through SQL query.

try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class 
    string query = "SELECT CustomerID FROM FQN.Customer WHERE $Group$ = ?";

    /// Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);

    // Providing parameters for query
    queryCommand.Parameters.Add("$Group$", "Important Customers");

    // Executing QueryCommand through ICacheReader
    ICacheReader reader = cache.SearchService.ExecuteReader(queryCommand);

    // Check if the result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            string CustomerID = reader.GetValue<string>(1);
            // Perform operations
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures 
        // Operation Timeout
        // Operation performed during state transfer    
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentException, ArgumentNullException    
}

try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class
    String query = "SELECT CustomerID FROM FQN.Customer WHERE $Group$ = ?";

    /// Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);

    // Providing parameters for query
    queryCommand.getParameters().put("$Group$", "Important Customers");

    // Executing QueryCommand through cacheReader
    CacheReader reader = cache.getSearchService().executeReader(queryCommand);

    // Check if the result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            String CustomerID = reader.getValue(1 , String.class);
            // Perform operations
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex)
{
    if (ex.getErrorCode() == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like NullPointerException or IllegalArgumentException
}

// This is an async method
try
{
    // Pre-conditions: Cache is already connected
    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class 
    var query = "SELECT $Group$ FROM FQN.Customer WHERE CustomerName = ?";

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);

    // Providing parameters for query
    var parameters = this.map.set("$Group","Important Customers");
    queryCommand.setParameters(parameters);

    // Executing QueryCommand         
    var searchService = await this.cache.getSearchService();
    var cacheReader = await searchService.executeReader(queryCommand);

    // Check if the result set is not empty
    if (cacheReader.getFieldCount() > 0)
    {
        while (cacheReader.read())
        {
            // Perform operations
            var groupName = cacheReader.getValue(1);                   
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch(error)
{
   // Handle errors
}

try:
    # Pre-conditions: Cache is already connected
    # Items with groups exist in cache
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Search for items with group
    # Provide Fully Qualified Name(FQN) of your custom class
    query = "SELECT $Group$ FROM FQN.Customer WHERE customer_name = ?"

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)

    # Providing parameters for query
    parameters = {"$Group": "Important Customers"}
    query_command.set_parameters(parameters)

    # Executing QueryCommand

    search_service = cache.get_search_service()
    cache_reader = search_service.execute_reader(query_command)

    # Check if the result set is not empty
    if cache_reader.get_field_count() > 0:
        while cache_reader.read():
            # Perform operations
            group_name = cache_reader.get_value(str, 1)
    else:
        # None query result set retrieved
        print("Query result is None")
except Exception as exp:
    # Handle errors

try {
    // Pre-conditions: Cache is already connected

    // Items with groups exist in cache
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with group
    // Provide Fully Qualified Name (FQN) of your custom class
    val query = "SELECT CustomerID FROM FQN.Customer WHERE $Group$ = ?"

    /// Use QueryCommand for query execution
    val queryCommand = new QueryCommand(query)

    // Providing parameters for query
    queryCommand.setParameters(Map("$Group$" -> "Important Customers"))

    // Executing QueryCommand through cacheReader
    val reader = cache.getSearchService.executeReader(queryCommand)

    // Check if the result set is not empty
    if (reader.getFieldCount > 0) {
      while (reader.read) {
      val CustomerID = reader.getValue(1, classOf[String])
      // Perform operations
      }
    } else {
      // Null query result set retrieved
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}