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Add Introduction to Memory-Optimized Tables

Freya Lamaro 2025-08-07 21:18:45 +08:00
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Introduction to Memory-Optimized Tables.-.md Normal file

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<br>Memory-optimized tables are created using CREATE Desk (Transact-SQL). Memory-optimized tables are totally durable by default, and, like transactions on (conventional) disk-primarily based tables, transactions on memory-optimized tables are totally atomic, constant, remoted, and durable (ACID). Memory-optimized tables and natively compiled stored procedures assist solely a subset of Transact-SQL features. Starting with SQL Server 2016, and in Azure SQL Database, there are not any limitations for collations or code pages which are specific to In-Memory OLTP. The first storage for memory-optimized tables is the primary memory. Rows within the desk are learn from and written to memory. A second copy of the [table knowledge](https://openclipart.org/search/?query=table%20knowledge) is maintained on disk, but only for sturdiness purposes. See Creating and Managing Storage for Memory-Optimized Objects for more details about durable tables. Information in memory-optimized tables is just read from disk during database recovery (for example, after a server restart). For even greater efficiency gains, In-Memory OLTP supports durable tables with transaction durability delayed. Delayed durable transactions are saved to disk soon after the transaction commits and management is returned to the consumer.<br>
<br>In change for the elevated efficiency, dedicated transactions that are not persisted to disk are misplaced in a server crash or fail over. Apart from the default durable memory-optimized tables, SQL Server additionally supports non-durable memory-optimized tables, which aren't logged and their knowledge isn't persisted on disk. Which means that transactions on these tables don't require any disk IO, however the information is lost if there is a server crash or failover. In-Memory OLTP is integrated with SQL Server to offer a seamless expertise in all areas equivalent to development, deployment, manageability, and supportability. A database can include in-memory as well as disk-based objects. Rows in memory-optimized tables are versioned. This implies that each row within the table probably has a number of versions. All row versions are maintained in the identical table information structure. Row versioning is used to permit concurrent reads and [Memory Wave System](https://vandalismwiki.uk/wiki/Blueberry_Supplementation_Improves_Memory_In_Older_Adults) writes on the same row. For more information about concurrent reads and writes on the same row, see Transactions with Memory-Optimized Tables.<br>
<br>The following figure illustrates multi-versioning. The figure reveals a table with three rows and each row has totally different versions. The desk has three rows: r1, r2, and r3. 1 has three versions, r2 has two variations, and r3 has four versions. Totally different versions of the same row do not necessarily occupy consecutive memory areas. The different row versions could be dispersed all through the desk data structure. The [Memory Wave System](http://forum.artefakt.cz//profile.php?id=1002431)-optimized desk knowledge structure may be seen as a group of row versions. Rows in disk-based mostly tables are organized in pages and extents, and individual rows addressed using page quantity and page offset, row variations in memory-optimized tables are addressed using 8-byte memory pointers. Through natively compiled stored procedures. By interpreted Transact-SQL, outdoors of a natively compiled saved procedure. These Transact-SQL statements may be either inside interpreted stored procedures or they may be advert hoc Transact-SQL statements. Memory-optimized tables could be accessed most effectively from natively compiled saved procedures (Natively Compiled Stored Procedures).<br>
<br>Memory-optimized tables will also be accessed with (traditional) interpreted Transact-SQL. Interpreted Transact-SQL refers to accessing memory-optimized tables with no natively compiled stored process. Some examples of interpreted Transact-SQL entry embrace accessing a memory-optimized table from a DML trigger, advert hoc Transact-SQL batch, view, and desk-valued perform. The next desk summarizes native and interpreted Transact-SQL entry for varied objects. 1You can't access a memory-optimized desk or natively compiled saved procedure from the context connection (the connection from SQL Server when executing a CLR module). You may, nonetheless, create and open one other connection from which you'll entry memory-optimized tables and natively compiled saved procedures. Sensitive knowledge in memory-optimized tables can be protected by utilizing At all times Encrypted. When utilizing All the time Encrypted with safe enclaves, the usage of enclave-enabled keys for columns in memory-optimized tables isn't supported. This means that in-place encryption can't be used, and the initial encryption is completed on the consumer.<br>
<br>At all times Encrypted isn't supported for any column in a memory-optimized table when the table is referenced in a natively compiled module. Communication: An software using many short saved procedure calls may see a smaller efficiency gain in comparison with an utility with fewer calls and more performance implemented in every stored process. Transact-SQL Execution: In-Memory OLTP achieves one of the best efficiency when using natively compiled saved procedures somewhat than interpreted stored procedures or query execution. There generally is a benefit to accessing memory-optimized tables from such saved procedures. Vary Scan vs Point Lookup: Memory-optimized nonclustered indexes help range scans and ordered scans. For point lookups, memory-optimized hash indexes have better performance than memory-optimized nonclustered indexes. Memory-optimized nonclustered indexes have higher performance than disk-based indexes. Starting in SQL Server 2016, the question plan for a memory-optimized desk can scan the table in parallel. This improves the performance of analytical queries. Index operations: Index operations aren't logged, they usually exist solely in memory.<br>