Cache Data Dependency on SQL Server
Note
This feature is only available in NCache Enterprise Edition.
There are various mechanisms in NCache to keep the data synced across the cache. There may be a scenario where the user wants to keep the data synced with the database, so every database update notifies the cache. This way data in the cache remains fresh, and operations occur on the updated data set.
NCache provides the feature of SQL dependency to synchronize cache with Microsoft SQL Server 2005 onwards. An item is added with SqlCacheDependency (provided by NCache), specifying an SQL statement representing a query result set in the database. NCache then establishes a link with the database against the result set. If an application updates, the SQL Server fires event notifications, which NCache catches and removes the corresponding item from the distributed cache.
Before using SQL Dependency, set up SQL Server Environment. To create SQL Dependency:
- Enable Broker Service
- Enable Database Permissions
For further details, please refer to the Setup SQL Server Environment section in Administrator's Guide.
Prerequisites
Add Data with SQL Dependency through API
To add data in the cache using SQL Dependency NCache provides the SqlCacheDependency
class. This adds items to the cache with SQL Dependency.
The following example adds SQL Dependency to an item and then adds the item to the cache using the Insert
method. The Insert
method adds a new item with dependency, and if this data already exists in the cache, it overwrites it.
try
{
// Creating connection string to get connected with database.
string connectionString = "your_connection_string_here";
// Getting products from database.
List<Product> products = FetchProductFromDB();
foreach (Product product in products)
{
string productKey = $"Product: {product.ProductID}";
// Creating an SQL dependency on the UnitPrice of product. Whenever the UnitPrice changes, the product is removed from the cache.
string query = $"SELECT UnitPrice FROM dbo.Products WHERE ProductID = {product.ProductID}";
// Creating dependency.
SqlCacheDependency dependency = new SqlCacheDependency(connectionString, query);
CacheItem productItem = new CacheItem(product);
// Adding Dependency to product item
productItem.Dependency = dependency;
// Adding CacheItem in cache
_cache.Add(productKey, productItem);
}
}
catch (OperationFailedException ex)
{
// Make sure that the query is valid
// Exception can occur due to:
// Connection Failures
// Operation Timeout
// Operation performed during state transfer
}
catch (Exception ex)
{
// Any generic exception like ArgumentNullException or ArgumentException
// Exception may occur due to incorrect connection string or broker not enabled
}
try
{
// Creating a connection string to establish connection with the database
String connString = "your_connection_string_here";
Connection connectionString = DriverManager.getConnectionconnStri(ng);
// Creating the query which selects the data on which cache data is dependent
String query = "SELECT CustomerID, Address, City FROM dbo.Customers WHERE CustomerID = ?";
QueryCommand queryCommand = new QueryCommand(query);
queryCommand.getParameters().put("CustomerID", customerId);
// Creating SQL dependency
SqlCacheDependency sqlDependency = new SqlCacheDependency(String.valueOf(connString), query);
// Get orders against customerId
Order[] orders = fetchOrdersByCustomerId(customerId);
for (Order order : orders) {
// Generate a unique key for this order
String key = "Order:" + order.orderId;
// Create a new cache item and add sql dependency to it
CacheItem cacheItem = new CacheItem(order);
cacheItem.setDependency(sqlDependency);
// Add cache item in the cache with sql dependency
cache.insert(key, cacheItem);
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
}
catch (OperationFailedException ex)
{
// Exception can occur due to:
// Connection Failures
// Operation Timeout
// Operation performed during state transfer
}
catch (Exception ex)
{
// Any generic exception like IllegalArgumentException or NullPointerException
}
try {
// Creating a connection string to establish connection with the database
val connString = "your_connection_string_here"
val customerId = "ALFKI"
// Creating the query which selects the data on which cache data is dependent
val query = "SELECT CustomerID, Address, City FROM dbo.Customers WHERE CustomerID = ?"
val queryCommand = new QueryCommand(query)
queryCommand.setParameters(Map("CustomerID" -> customerId))
// Creating SQL dependency
val sqlDependency = new SqlCacheDependency(connString, query)
// Get orders against customerId
val orders = fetchOrdersByCustomerId(customerId)
for (order <- orders) {
// Generate a unique key for this order
val key = "Order:" + order.getOrderId
// Create a new cache item and add sql dependency to it
val cacheItem = CacheItem(order)
cacheItem.setDependency(sqlDependency)
// Add cache item in the cache with sql dependency
cache.insert(key, cacheItem)
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
}
catch {
case exception: Exception => {
// Handle any errors
}
}
// This is an async method
try
{
// Creating a connection string to establish connection with the database
var connection = new ActiveXObject("adodb.connection");
let connString = "your_connection_string_here";
let query = "SELECT CustomerID, Address, City FROM dbo.Customers WHERE CustomerID = ?";
let queryCommand = new QueryCommand(query);
queryCommand.getParameters().put("CustomerID", this.customerId);
connection.Open(query, connString);
// Creating SQL dependency
let sqlDependency = new ncache.SqlCacheDependency(connString, query);
// Get orders against customerId
let orders = await this.fetchOrdersByCustomerId(this.customerId);
for (let order in orders)
{
// Generate a unique key for this order
let key = "Order:" + order.OrderId;
// Create a new cache item and add sql dependency to it
let cacheItem = new ncache.CacheItem(order);
cacheItem.setDependency(sqlDependency);
// Add cache item in the cache with sql dependency
await this.cache.insert(key, cacheItem);
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
connection.close();
}
catch (error)
{
// Handle any errors
}
try:
# Creating a connection string to establish connection with the database
conn_string = "your_connection_string_here"
query = "SELECT CustomerID, Address, City FROM dbo.Customers WHERE CustomerID = ?"
query_command = ncache.QueryCommand(query)
query_command.set_parameters({"CustomerID": "ALFKI"})
# Creating SQL dependency
sql_dependency = ncache.SqlCacheDependency(conn_string, query)
# Get orders against Customer ID
orders = fetch_orders_by_customer_id("ALFKI")
for order in orders:
# Generate a unique key for this order
key = "Order:" + order.get_order_id()
# Create a new cache item and add sql dependency to it
cache_item = ncache.CacheItem(order)
cache_item.set_dependency(sql_dependency)
# Add cache item in the cache with sql dependency
cache.insert(key, cache_item)
# For successful addition of item with SQL Dependency
# Update the record in the database and check if key is present
except Exception as exp:
# Handle errors
Note
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
Add Data with SQL Dependency using Stored Procedure
NCache lets you provide a SQL Dependency on an item using a stored procedure. You can also specify the parameters to be passed along with this procedure using the SqlCacheDependency
method.
The following example adds an item to the cache with SQL Dependency through the stored procedure using the Insert method. The Insert
method adds a new item with dependency, and if this data already exists in the cache, it overwrites its properties.
// Creating connection string to get connected with database.
string connectionString = "your_connection_string_here";
string spGetUnitPriceByProductID = "sp_GetUnitPriceByProductID";
// Getting products from database.
List<Product> products = FetchProductFromDB();
// Creating dictionary of CacheItems.
Dictionary<string, CacheItem> cacheItems = new Dictionary<string, CacheItem>();
foreach (Product product in products)
{
string productKey = $"Product: {product.ProductID}";
// Creating Param to be passed in stored procedure dictionary.
SqlCmdParams paramProductID = new SqlCmdParams
{
Type = CmdParamsType.Int,
Value = product.ProductID
};
// Creating stored procedure params.
Dictionary<string, SqlCmdParams> parameters = new Dictionary<string, SqlCmdParams>();
parameters.Add("@ProductID", paramProductID);
CacheItem productItem = new CacheItem(product);
// Creating an SQL dependency on the UnitPrice of product. Whenever the UnitPrice changes, the product is removed from the cache.
SqlCacheDependency dependency = new SqlCacheDependency(connectionString, spGetUnitPriceByProductID, SqlCommandType.StoredProcedure, parameters);
// Adding Dependency to product item
productItem.Dependency = dependency;
cacheItems.Add(productKey, productItem);
}
// Adding CacheItems in cache
_cache.AddBulk(cacheItems);
// Creating a connection string to establish connection with the database
String connString = "";
Connection connectionString = DriverManager.getConnection(connString);
// Name of the stored procedure item is dependent un
String storedProcName = "GetCustomerByID";
// Specify the customerID passed as parameters
Map<String, SqlCmdParams> sqlCmdParams = new HashMap;
sqlCmdParams.put("CustomerID", customerId);
// Create sql dependency
// In case the stored procedure has no parameters, pass null as the SqlCmdParams value
SqlCacheDependency sqlCacheDependency = new SqlCacheDependency(String.valueOf(connectionString), storedProcName,
SqlCommandType.StoredProcedure, sqlCmdParams);
// Get orders from database against customerId
Order[] orders = fetchOrdersByCustomerId(customerId);
for (Order order : orders)
{
// Generate a unique cache key for this order
String key = "Order:" + order.orderId;
// Create a new cache item and add sql dependency to it
CacheItem item = new CacheItem(order);
item.setDependency(sqlCacheDependency);
// Add cache item in the cache with sql dependency
cache.insert(key, item);
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
// Creating a connection string to establish connection with the database
val connString = "YourConnString"
val customerId = "ALFKI"
// Name of the stored procedure item is dependent un
val storedProcName = "GetCustomerByID"
// Specify the customerID passed as parameters
var param = SqlCmdParams()
param.setValue(customerId)
var sqlCmdParams: Map[String, SqlCmdParams] = Map("CustomerID" -> param)
// Create sql dependency
// In case the stored procedure has no parameters, pass null as the SqlCmdParams value
val sqlCacheDependency = SqlCacheDependency(
connString,
storedProcName,
SqlCommandType.StoredProcedure,
sqlCmdParams
)
// Get orders from database against customerId
var orders = fetchOrdersByCustomerId(customerId)
for (order <- orders)
{
// Generate a unique cache key for this order
var key = "Order:" + order.getOrderId
// Create a new cache item and add sql dependency to it
var item = CacheItem(order)
item.setDependency(sqlCacheDependency)
// Add cache item in the cache with sql dependency
cache.insert(key, item)
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
// This is an async method
// Creating a connection string to establish connection with the database
var connection = new ActiveXObject("adodb.connection");
let connString = "your_connection_string_here";
connection.Open(connString);
// Name of the stored procedure item is dependent un
let storedProcName = "GetCustomerByID";
// Specify the customerID passed as parameters
let sqlCmdParams = new Map();
sqlCmdParams.set("CustomerID", this.customerId);
// Create sql dependency
// In case the stored procedure has no parameters, pass null as the SqlCmdParams value
let sqlCacheDependency = new ncache.SqlCacheDependency(connString, storedProcName,
ncache.SqlCommandType.StoredProcedure, sqlCmdParams);
// Get orders from database against customerId
let orders = await this.fetchOrdersByCustomerId(this.customerId);
for (let order in orders)
{
// Generate a unique cache key for this order
let key = "Order:" + order.OrderId;
// Create a new cache item and add sql dependency to it
let item = new ncache.CacheItem(order);
item.setDependency(sqlCacheDependency);
// Add cache item in the cache with sql dependency
this.cache.insert(key, item);
// For successful addition of item with SQL Dependency
// Update the record in the database and check if key is present
}
connection.close();
# Creating a connection string to establish connection with the database
conn_string = "your_connection_string_here"
# Name of the stored procedure item is dependent upon
stored_proc_name = "GetCustomerByID"
# Specify the customerID passed as parameters
sql_cmd_params = {"CustomerID": "ALFKI"}
# Create sql dependency
# In case the stored procedure has no parameters, pass null as the SqlCmdParams value
sql_cache_dependency = ncache.SqlCacheDependency(conn_string, stored_proc_name, ncache.SqlCommandType.STORED_PROCEDURE, sql_cmd_params)
# Get orders from database against customerId
orders = fetch_orders_by_customer_id("ALFKI")
for order in orders:
# Generate a unique cache key for this order
key = "Order:" + order.get_order_id()
# Create a new cache item and add sql dependency to it
item = ncache.CacheItem(order)
item.set_dependency(sql_cache_dependency)
# Add cache item in the cache with sql dependency
cache.insert(key, item)
# For successful addition of item with SQL Dependency
# Update the record in the database and check if key is present
Important
In an environment where the user has more restricted access to the database, users are supposed to create SQL Service and Queue per NCache process by checking “Use custom SQL Notification Mode” checkbox in Options tab in NCache Manager.
You can also create the required SQL Service and Queue using script NCacheServiceQueue.sql located at %NCHOME%/bin/resources
.
Additional Resources
NCache provides sample application for SQL dependency on GitHub.
See Also
Cache Dependency on Oracle Database
Cache Dependency on OleDB
CLR Procedures in SQL Server with Cache
Locking Data For Concurrency Control
Cache Data Dependency on External Source