When I mention migration, I mean tables, referential integrity, check constraint and so on. My conclusion is that In-Memory OLTP does not support migrations in most cases. Even if you could access disk-based tables from natively compiled triggers, they only support AFTER triggers which are not really useful for referential integrity since you can’t rollback a transaction. Furthermore, if you would like to use triggers to establish referential integrity, you get another surprise: there are no possibilities to access disk-based tables in natively compiled triggers, and only that kind of trigger (natively compiled) is allowed on In-Memory optimized tables. Basically, you will end up with a database without referential integrity. Foreign keys between In-Memory and disk-based tables are not supported. It’s not possible to establish a relationship between an In-Memory table and a disk-based table.
If you decide to migrate a small number of tables, you will get another unpleasant surprise.
Furthermore, the Advisor must be run on once for every table. The Advisor stops working on the first error which includes foreign keys, incompatible types, more than 8 indexes on a table, and so on ( NOTE: The limitation of 8 indexes is overcome in SQL Server 2017). By comparing known databases with the In-Memory ‘equivalent’, we can judge how powerful In-Memory OLTP technology is.Īlthough there is a Memory Optimization Advisor in SSMS, see image below, a wizard that will help you in migrating your tables, you will be, in most cases, unable to migrate your existing database to In-Memory OLTP using this tool. Furthermore, we know the potential bottlenecks. Why? Because we know our data and we know the weaknesses of our database normalization. What is the main use case? Many of us would like to port our (known) databases to In-Memory technology. Even with SQL Server 2017, we have the same situation today. They also made many improvements in this technology but, in my opinion, the main use case is still not supported. Then a few years later, Microsoft made us happy when releasing SP1 for SQL Server 2016 by making In-Memory OLTP available for any edition. First, this technology was available only in Enterprise (the most expensive) Edition, and, furthermore, it had a lot of limitations. When the final release came to light, I was very disappointed. In the pre-release mode, I saw quite a few videos that demonstrate the strength of this new technology. Microsoft In-Memory OLTP was introduced with SQL Server 2014. In each row, each column value is embedded into and clauses.Converting a Database to In-Memory OLTP - Simple Talk On clicking the link, we will see the following document in a new query window of SSMS as follows.įOR XML PATH will create an XML document where each row is embedded into and clause. This query will create a hyperlink as an output. The FOR XML AUTO class creates an XML document where each column is an attribute. There are two common ways to convert data from SQL tables into XML format as follows. Methods of converting tables in T-SQL into XML : Reading data to verify – SELECT * FROM Employee_Table
Inserting data into Employee_Table – insert into Employee_Table ( Name,City,Salary)
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