Compare Exchange in Cluster-Wide Session

• Compare-Exchange items can be created and managed on the advanced session (Session.Advanced)
  Other options are listed in this compare-exchange overview.

• When working with compare-exchange items from the session,
  the session must be opened as a cluster-wide session.

• In this page:

  • Create compare-exchange
  • Get compare-exchange
  • Delete compare-exchange

Create compare-exchange

Example

• Sync
• Async

// The session must be first opened with cluster-wide mode
session.Advanced.ClusterTransaction.CreateCompareExchangeValue(
  key: "Best NoSQL Transactional Database",
  value: "RavenDB"
);

session.SaveChanges();

// The session must be first opened with cluster-wide mode
session.Advanced.ClusterTransaction.CreateCompareExchangeValue(
  key: "Best NoSQL Transactional Database",
  value: "RavenDB"
);

await session.SaveChangesAsync();

• SaveChanges() throws a ConcurrencyException if the key already exists.
• An InvalidOperationException exception is thrown if the session was Not opened as cluster-wide.

Syntax

• Sync
• Async

session.Advanced.ClusterTransaction.CreateCompareExchangeValue<T>(key, value);

session.Advanced.ClusterTransaction.CreateCompareExchangeValue<T>(key, value);

Parameters	Type	Description
key	string	The compare-exchange item key. This string can be up to 512 bytes.
value	T	The associated value to store for the key

Return Value	Description
CompareExchangeValue<T>	The new compare-exchange item is returned

The CompareExchangeValue

Parameters	Type	Description
key	string	The compare-exchange item key. This string can be up to 512 bytes.
value	T	The value associated with the key
index	long	Index for concurrency control

Get compare-exchange

Get single value

• Sync
• Async

session.Advanced.ClusterTransaction.GetCompareExchangeValue<T>(key);

await session.Advanced.ClusterTransaction.GetCompareExchangeValueAsync<T>(key);

Parameters	Type	Description
key	string	The key to retrieve

Return Value	Description
CompareExchangeValue<T>	If the key doesn't exist it will return null

Get multiple values

• Sync
• Async

session.Advanced.ClusterTransaction.GetCompareExchangeValues<T>(keys);

await session.Advanced.ClusterTransaction.GetCompareExchangeValuesAsync<T>(keys);

Parameters	Type	Description
keys	string[]	Array of keys to retrieve

Return Value	Description
Dictionary<string, CompareExchangeValue<T>>	If a key doesn't exists the associate value will be null

Get compare-exchange lazily

• Sync
• Async

// Single value
session.Advanced.ClusterTransaction.Lazily.GetCompareExchangeValue<T>(key);

// Multiple values
session.Advanced.ClusterTransaction.Lazily.GetCompareExchangeValues<T>(keys);

// Single value
session.Advanced.ClusterTransaction.Lazily.GetCompareExchangeValueAsync<T>(key);

// Multiple values
session.Advanced.ClusterTransaction.Lazily.GetCompareExchangeValuesAsync<T>(keys);

Parameters	Type	Description
key	string	The key to retrieve
keys	string[]	Array of keys to retrieve

Return Value	Description
Lazy<CompareExchangeValue<T>>	If the key doesn't exist it will return null
Lazy<Dictionary<string, CompareExchangeValue<T>>>	If a key doesn't exists the associate value will be null

Delete compare-exchange

• Sync
• Async

// Delete by key & index
session.Advanced.ClusterTransaction.DeleteCompareExchangeValue(key, index);

// Delete by compare-exchange item
session.Advanced.ClusterTransaction.DeleteCompareExchangeValue<T>(item);

// Delete by key & index
session.Advanced.ClusterTransaction.DeleteCompareExchangeValue(key, index);

// Delete by compare-exchange item
session.Advanced.ClusterTransaction.DeleteCompareExchangeValue<T>(item);

Parameters	Type	Description
key	string	The key of the compare-exchange item to delete
index	long	The index of this compare-exchange item
item	CompareExchangeValue<T>	The compare-exchange item to delete