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Search Tag Data in Cache with SQL

Note

This feature is only available in NCache Enterprise Edition.

NCache provides object queries through which you can search and delete result sets based on the criteria given to the query. To retrieve the data according to your specified criteria, NCache provides you with an extension of SQL. It lets you search the data in your cache based on the criteria on which requirement is based.

A special keyword $Tag$ is used to specify that the condition under consideration uses tags. 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.

Similar to the retrieve and delete method,the three strategies of querying items on tags (i.e. by a specific tag, any tag or all tags) can also be adopted for these queries which are explained below.

Prerequisites

  • .NET/.NET Core
  • Java
  • Node.js
  • Python
  • Scala
  • Install the following NuGet package in your application:
    • Enterprise: Alachisoft.NCache.SDK
  • Include the following namespace in your application:
    • Alachisoft.NCache.Client
    • Alachisoft.NCache.Runtime.Caching
    • Alachisoft.NCache.Runtime.Exceptions
  • 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>
  • Import 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.

Search Data in Cache with One Tag

Using object queries, a single tag can be used to retrieve all the items associated with that tag.

Syntax

Following example retrieves all the items associated with the tag Beverages using the SQL query.

Warning

Providing Null tag value for the query will throw an ArgumentNullException or NullPointerException.

  • .NET/.NET Core
  • Java
  • Node.js
  • Python
  • Scala
try
{
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with tags
    // Use the Fully Qualified Name (FQN) of your own custom class   
    string query = "Select $Value$ FROM FQN.Customer WHERE $Tag$ = ?";

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);
    queryCommand.Parameters.Add("$Tag$", "Important Customers");

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

    // Check if result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            Customer result = reader.GetValue<Customer>(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 are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with tags
    // Use the Fully Qualified Name (FQN) of your own custom class   
    string query = "Select $Value$ FROM FQN.Customer WHERE $Tag$ = ?";

    // Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);
    queryCommand.getParameters().put("$Tag$", "Important Customers");

    // Executing query
    CacheReader reader = cache.getSearchService().executeReader(queryCommand);

    // Check if result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            Customer result = reader.getValue(1,Customer.class);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch (OperationFailedException ex) {

    if (ex.getErrorCode() == NCacheErrorCodes.INCORRECT_FORMAT) 
    {
        // Make sure the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation performed during state transfer
        // Operation Timeout
    }
}
catch (Exception ex) 
{
  // Any generic exception like NullPointerException or IllegalArgumentException
}
// This is an async method
try
{
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with tags
    // Use the Fully Qualified Name (FQN) of your own custom class   
    var query = "Select $Value$ FROM FQN.Customer WHERE $Tag$ = ?";

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);
    queryCommand.getParameters().set("$Tag$", "Important Customers");

    // Executing query
    var searchService = await this.cache.getSearchService();
    var reader = await searchService.executeReader(queryCommand);

    // Check if result set is not empty

    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            var result = reader.getValue(1);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch(error)
{
    // Handle errors
}
try:
    # Pre-conditions: Cache is already connected
    # Items are already present in the cache with tags
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Search for items with tags
    # Use the Fully Qualified Name(FQN) of your own custom class
    query = "Select $Value$ FROM FQN.Customer WHERE $Tag$ = ?"

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)
    query_command.set_parameters({"$Tag$": "Important Customers"})

    # Executing query
    search_service = cache.get_search_service()
    reader = search_service.execute_reader(query_command)

    # Check if result set is not empty

    if reader.get_field_count() > 0:
        while reader.read():
            # Get the value of the result set
            result = reader.get_value(Customer, 1)
    else:
        # None query result set retrieved
        print("Result set is None")
except Exception as exp:
    # Handle errors
try {
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Search for items with tags
    // Use the Fully Qualified Name (FQN) of your own custom class
    val query = "Select $Value$ FROM FQN.Customer WHERE $Tag$ = ?"

    // Use QueryCommand for query execution
    val queryCommand = new QueryCommand(query)
    queryCommand.setParameters(Map("$Tag$" -> "Important Customers"))

    // Executing query
    val reader = cache.getSearchService.executeReader(queryCommand)

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

Search Data in Cache with ANY Tag

Using object queries, if multiple tags are provided in the form of a list, items associated with ANY of the tags from the list are retrieved.

Syntax

Following example retrieves all the items associated with any of the tags from the list using the SQL query.

Warning

Providing Null tag value for the query will throw an ArgumentNullException or NullPointerException.

Note

Use fully-qualified name of the class Customer e.g. Data.Customer.

  • .NET/.NET Core
  • Java
  • Node.js
  • Python
  • Scala
try
{
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    string query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ IN (?,?,?)";

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList = new ArrayList();
    queryTagList.Add("Important Customers");
    queryTagList.Add("East Coast Customers");
    queryTagList.Add("West Coast Customers");

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);
    queryCommand.Parameters.Add("$Tag$", queryTagList);

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

    // Check if result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            Customer result = reader.GetValue<Customer>(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 are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    string query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ IN (?,?,?)";

    // If multiple tags are used for query criteria, add tags in an array list
    ArrayList queryTagList = new ArrayList();
    queryTagList.add("Important Customers");
    queryTagList.add("East Coast Customers");
    queryTagList.add("West Coast Customers");

    // Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);
    queryCommand.getParameters().put("$Tag$", queryTagList);

    // Executing query
    CacheReader reader = cache.getSearchService().executeReader(queryCommand);

    // Check if result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            Customer result = reader.getValue(1,Customer.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 are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    var query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ IN (?,?,?)";

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList = [];
    queryTagList.push("Important Customers");
    queryTagList.push("East Coast Customers");
    queryTagList.push("West Coast Customers");

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);
    queryCommand.getParameters().set("$Tag$", queryTagList);

    // Executing query
    var searchService = await this.cache.getSearchService();
    var reader = await searchService.executeReader(queryCommand);

    // Check if result set is not empty

    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            var result = reader.getValue(1);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch(error)
{
   /// Handle errors
}
try:
    # Pre-conditions: Cache is already connected
    # Items are already present in the cache with tags
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Search for items with tags
    # Use the Fully Qualified Name(FQN) of your own custom class
    query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ IN (?,?,?)"

    # If multiple tags are used for query criteria, add tags in a list
    query_tag_list = [
        "Important Customers",
        "East Coast Customers",
        "West Coast Customers"
    ]

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)
    query_command.set_parameters({"$Tag$": query_tag_list})

    # Executing query
    search_service = cache.get_search_service()
    reader = search_service.execute_reader(query_command)

    # Check if result set is not empty

    if reader.get_field_count() > 0:
        while reader.read():
            # Get the value of the result set
            result = reader.get_value(Customer, 1)
    else:
        # None query result set retrieved
        print("Result set is None")
except Exception as exp:
    # Handle errors
try {
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    val query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ IN (?,?,?)"

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList: List[Tag] = List()
    queryTagList = Tag("Important Customers") :: queryTagList
    queryTagList = Tag("East Coast Customers") :: queryTagList
    queryTagList = Tag("West Coast Customers") :: queryTagList

    // Use QueryCommand for query execution
    val queryCommand = new QueryCommand(query)
    queryCommand.setParameters(Map("$Tag$" -> queryTagList))

    // Executing query
    val reader = cache.getSearchService.executeReader(queryCommand)

    // Check if result set is not empty
    if (reader.getFieldCount > 0) {
      while (reader.read) {
        // Get the value of the result set
        val result = reader.getValue(1, classOf[Customer])
      }
    }
    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 Data in Cache with ALL Tags

Using object queries, if multiple tags are provided in the form of a list, items associated with ALL of the tags from the list are retrieved. It means that an item is not retrieved unless it contains all the tags in the list.

Syntax

Following example retrieves all the items associated with all of the tags from the list using the SQL query.

Warning

Providing Null tag value for the query will throw an ArgumentNullException or NullPointerException.

Note

Use fully-qualified name of the class Customer e.g. Data.Customer.

  • .NET/.NET Core
  • Java
  • Node.js
  • Python
  • Scala
try
{
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    string query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ = ? AND $Tag$ = ?"; 

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList = new ArrayList();
    queryTagList.Add("Important Customers");
    queryTagList.Add("East Coast Customers");

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);
    queryCommand.Parameters.Add("$Tag$", queryTagList);

    // Execute query
    ICacheReader reader = cache.SearchService.ExecuteReader(queryCommand);

    // Check if result set is not empty
    if (reader.FieldCount > 0)
    {
        while (reader.Read())
        {
            // Get the value of the result set
            Customer result = reader.GetValue<Customer>(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 are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    string query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ = ? AND $Tag$ = ?"; 

    // If multiple tags are used for query criteria, add tags in an array list
    ArrayList queryTagList = new ArrayList();
    queryTagList.add("Important Customers");
    queryTagList.add("East Coast Customers");

    // Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);
    queryCommand.getParameters().put("$Tag$", queryTagList);

    // Execute query
    CacheReader reader = cache.getSearchService().executeReader(queryCommand);

    // Check if result set is not empty
    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            Customer result = reader.getValue(1,Customer.class);            
        }
    }
    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 NullPointerException or IllegalArgumentException  
}
// This is an async method
try
{
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    var query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ = ? AND $Tag$ = ?"; 

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList = [];
    queryTagList.push("Important Customers");
    queryTagList.push("East Coast Customers");
    queryTagList.push("West Coast Customers");

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);
    queryCommand.getParameters().set("$Tag$", queryTagList);

    // Executing query
    var searchService = await this.cache.getSearchService();
    var reader = await searchService.executeReader(queryCommand);

    // Check if result set is not empty

    if (reader.getFieldCount() > 0)
    {
        while (reader.read())
        {
            // Get the value of the result set
            var result = reader.getValue(1);
        }
    }
    else
    {
        // Null query result set retrieved
    }
}
catch(error)
{
    // Handle errors
}
try:
    # Pre-conditions: Cache is already connected
    # Items are already present in the cache with tags
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Search for items with tags
    # Use the Fully Qualified Name(FQN) of your own custom class
    query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ = ? AND $Tag$ = ?"

    # If multiple tags are used for query criteria, add tags in a list
    query_tag_list = [
        "Important Customers",
        "East Coast Customers",
        "West Coast Customers"
    ]

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)
    query_command.set_parameters({"$Tag$": query_tag_list})

    # Executing query
    search_service = cache.get_search_service()
    reader = search_service.execute_reader(query_command)

    # Check if result set is not empty

    if reader.get_field_count() > 0:
        while reader.read():
            # Get the value of the result set
            result = reader.get_value(Customer, 1)
    else:
        # None query result set retrieved
        print("Result set is None")
except Exception as exp:
    # Handle errors
try {
    // Pre-conditions: Cache is already connected
    // Items are already present in the cache with tags
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Finding items associated with any of the tags
    // Make sure to use the Fully Qualified Name (FQN)
    val query = "SELECT $Value$ FROM FQN.Customer WHERE $Tag$ = ? AND $Tag$ = ?"

    // If multiple tags are used for query criteria, add tags in an array list
    var queryTagList: List[Tag] = List()
    queryTagList = Tag("Important Customers") :: queryTagList
    queryTagList = Tag("East Coast Customers") :: queryTagList

    // Use QueryCommand for query execution
    val queryCommand = new QueryCommand(query)
    queryCommand.setParameters(Map("$Tag$" -> queryTagList))

    // Execute query
    val reader = cache.getSearchService.executeReader(queryCommand)

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

In order to get more detail on NCache queries please refer to the SQL Reference for NCache section.

Additional Resources

NCache provides sample application for Tags on GitHub.

See Also

Using Groups
Add/Update Data in Cache with Tags
Retrieve Cache Data with Tags
Remove Cache Data with Tags
Delete Tag Data from Cache with SQL
Named Tags

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