Telerik OpenAccess ORM

This topic provides overview of the Runtime Configuration settings. 

• Cache Reference Type - specifies the type of the references maintained by the cache of the OpenAccessContext:
  • AUTO - specifies that references to fetched data are strongly held and references to user instances are weakly held.
  • STRONG - specifies that all references can't be reclaimed.
  • WEAK - specifies that a reference is maintained using a System.WeakReference allowing the garbage collector to reclaim the object.
    
    

    For more information about the Cache Reference Type setting, refer to How to: Configure Garbage Collection.

• Class Behavior - defines the class behavior - ReadWrite/ReadOnly/InsertOnly:
  • Default or ReadWrite - allows full access to user data. All CRUD (Create, Read, Update and Delete) modifications are allowed.
  • Read Only - allows only reading user data. No CUD modifications (Create, Update or Delete) are allowed.
  • Insert Only - allows only insert and read operations for objects of this type.
• Compiled Query Cache - controls the maximum number of queries that are kept in the pre-compiled query cache. The pre-compiled query cache is the one that holds already computed translations from LINQ to the corresponding SQL expressions. This property controls the size of the compiled query cache. The default value is 0, which is internally translated to the default size of 1000. Negative numbers will lead to a size of 1000, too. The only reason to increase the value would be that you have more than 1000 different queries for which you need to store the compiled query information.
• Transaction Mode - controls which objects are locked when pessimistic concurrency control is used. The Commit operation will verify that modified objects have not been updated by another transaction meanwhile.
  • Optimistic (default) - concurrency control happens during transaction commit. Transaction conflicts will be detected during Transaction.Commit() and will cause Telerik.OpenAccess.Exceptions.OptimisticVerificationException. Transaction will verify that modified objects have not been updated by another transaction meanwhile. Only available with optimistic transactions.
  • Pessimistic Explicit -  concurrency control happens during entire transaction. Transaction conflicts will be detected for all reading/modifying methods and will cause Telerik.OpenAccess.Exceptions.LockNotGrantedException to be thrown.
  • Pessimistic Locking All - all objects are write-locked when fetched from the data store. Concurrency control happens during entire transaction. Transaction conflicts will be detected for all reading/modifying methods and will cause Telerik.OpenAccess.Exceptions.LockNotGrantedException to be thrown.
  • Pessimistic Locking First - first object is write-locked when fetched from the data store. Concurrency control happens during entire transaction. Transaction conflicts will be detected for all reading/modifying methods and will cause Telerik.OpenAccess.Exceptions.LockNotGrantedException to be thrown.
• Isolation Level - controls the transaction locking and row versioning behavior. The isolation level describes the degree to which the data being updated is visible to other transactions.
  • Unspecified - a different isolation level than the one specified is being used, but the level cannot be determined. If you set the IsolationLevel to Unspecified, the transaction executes according to the isolation level that is determined by the driver that is being used.
  • Chaos - the pending changes from more highly isolated transactions cannot be overwritten. Behaves the same way as ReadUncommitted, but checks the isolation level of other pending transactions during a write operation so that transactions with more restrictive isolation levels are not overwritten.
  • Read Uncommitted - the Read Uncommitted isolation level allows a task to read data that can be in the middle of being modified by another transaction, uncommitted changes to data in the database. This is also known as dirty read. Values in the data can be changed and rows can appear or disappear in the data set before the end of the transaction.
  • Read Committed (Default) - the Read Committed isolation level specifies that a transaction can read only committed changes to data. It cannot read data that has been modified but not committed by other transactions. Data can be changed by other transactions between individual statements within the current transaction. If a transaction needs to read a row that has been modified by an incomplete transaction in another session, the transaction waits until the first transaction completes.
  • Repeatable Read - it means that the transaction will lock all the data that is used in the query and another transaction cannot update the data until the current transaction completes. Other transactions can insert new rows that match the search conditions of statements issued by the current transaction. If the current transaction then retries the statement it will retrieve the new rows, which results in phantom reads.
  • Serializable - this is the most restrictive isolation level which prevents other user from updating or inserting rows into the data set until the transaction completes. The Serializable isolation level also specifies that statements cannot read uncommitted changes to data in the database.
  • Snapshot - in databases, Snapshot isolation specifies that data read by any statement in a transaction will be the transactionally consistent version of the data that existed at the start of the transaction. A transaction executing under snapshot isolation appears to operate on a personal snapshot of the database, taken at the start of the transaction. Data modifications made by other transactions after the start of the current transaction are not visible to statements executing in the current transaction. The transaction itself will successfully commit only if no updates are made to the data by any concurrent updates made since that snapshot.
• Lock Timeout (msec) - when Telerik OpenAccess ORM cannot grant a lock to a transaction on a resource because another transaction already owns a conflicting lock on that resource, the first transaction becomes blocked waiting on the resources. The Lock Timeout settings allows Telerik OpenAccess ORM to set a maximum time that a statement waits on a blocked resources.
• Lock SQL Suffix - controls the SQL suffix that is appended for update operations.
• Medium Trust - if set to True, allows Telerik OpenAccess ORM to work in a medium trust environment (ASP.NET). Under medium trust, some operations cannot be performed and the OpenAccess runtime must be made aware of this. This affects things where privileged operations are needed.
• Multithreaded Context - supports multiple threads accessing one OpenAccessContext, i.e., one OpenAccessContext maybe used from more than one thread at the same time. Enabling the support for concurrent threads will turn on additional synchronization, which can affect the performance.
• Use UTC for DateTime - specifies whether to use Coordinated Universal Time format. The default value is False.
• Nulls First Sort - controls whether the database will use the NULLS FIRST sorting option (when you order by a certain column the position of the records that have null in that column). Not all database servers support this option. (For SQL server it is the default behavior – in oracle nulls are at the end so you have to set it to true to have the same behavior as sql server). The default value is True.
• Return Null on RowNotFound - controls whether null is to be returned when an object references an object that does not exist in the database by foreign key. When false RownNotFoundException is being thrown.

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