Compare Exchange: How to Delete Compare Exchange Value

• Use DeleteCompareExchangeValueOperation to delete a Key and its Value.

• The Key and its Value are deleted only if the index in the request matches the current index stored in the server for the specified key.

• For an overview of the 'Compare Exchange' feature click: Compare Exchange Overview

• In this page:

  • Syntax
  • Example

Syntax

Method:

public DeleteCompareExchangeValueOperation(string key, long index)

Parameters
key	string	The key to be deleted
index	long	The version number of the value to be deleted

Returned object:

public class CompareExchangeResult<T>
{
  public bool Successful;
  public T Value;
  public long Index;
}

Return Value
Successful	bool	* True if the delete operation was successfully completed

• True if key doesn't exist
• False if the delete operation failed |
  | Value | T | * The value that was deleted upon a successful delete
• 'null' if key doesn't exist
• The currently existing value on the server if delete operation failed |
  | Index | long | * The next available version number upon success
• The next available version number if key doesn't exist
• The currently existing index on the server if the delete operation failed |

Example

// First, get existing value
CompareExchangeValue<User> readResult =
  store.Operations.Send(
      new GetCompareExchangeValueOperation<User>("AdminUser"));

// Delete the key - use the index received from the 'Get' operation
CompareExchangeResult<User> deleteResult
  = store.Operations.Send(
      new DeleteCompareExchangeValueOperation<User>("AdminUser", readResult.Index));

// The delete result is successful only if the index has not changed between the read and delete operations
bool deleteResultSuccessful = deleteResult.Successful;