Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance
This application processes orders. There is a lot of processing on recent orders. There is not a lot of processing on older orders. Recent orders are in a memory-optimized table. Older orders are in a disk-based table. All orders after the hotDate are in the memory-optimized table. All orders before the hotDate are in the disk-based table. Assume an extreme OLTP workload with a lot of concurrent transactions. This business rule (recent orders in a memory-optimized table) must be enforced even if several concurrent transactions are attempting to change the hotDate.
This sample does not use a partitioned table for the disk-based table but does track an explicit split point between the two tables, using a third table. The split point can be used to ensure that newly inserted data is always inserted into the appropriate table based on the date. It could also be used to determine where to look for data. Late arriving data still goes into the appropriate table.
For a related sample, see Application Pattern for Partitioning Memory-Optimized Tables.
USE MASTER GO IF NOT EXISTS(SELECT name FROM sys.databases WHERE name = 'hkTest') CREATE DATABASE hkTest -- enable for In-Memory OLTP - change file path as needed ALTER DATABASE hkTest ADD FILEGROUP hkTest_mod CONTAINS MEMORY_OPTIMIZED_DATA ALTER DATABASE hkTest ADD FILE( NAME = 'hkTest_mod' , FILENAME = 'c:\data\hkTest_mod') TO FILEGROUP hkTest_mod; GO use hkTest go -- create memory-optimized table if OBJECT_ID(N'hot',N'U') IS NOT NULL drop table [hot] create table hot (id int not null primary key nonclustered, orderDate datetime not null, custName nvarchar(10) not null ) with (memory_optimized=on) go -- create disk-based table for older order data if OBJECT_ID(N'cold',N'U') IS NOT NULL drop table [cold] create table cold ( id int not null primary key, orderDate datetime not null, custName nvarchar(10) not null ) go -- the hotDate is maintained in this memory-optimized table. The current hotDate is always the single date in this table if OBJECT_ID(N'hotDataSplit') IS NOT NULL drop table [hotDataSplit] create table hotDataSplit ( hotDate datetime not null primary key nonclustered hash with (bucket_count = 1) ) with (memory_optimized=on) go -- Stored Procedures -- set the hotDate -- snapshot: if any other transaction tries to update the hotDate, it will fail immediately due to a -- write/write conflict if OBJECT_ID(N'usp_hkSetHotDate') IS NOT NULL drop procedure usp_hkSetHotDate go create procedure usp_hkSetHotDate @newDate datetime with native_compilation, schemabinding, execute as owner as begin atomic with ( transaction isolation level = snapshot, language = N'english' ) delete from dbo.hotDataSplit insert dbo.hotDataSplit values (@newDate) end go -- extract data up to a certain date [presumably the new hotDate] -- must be serializable, because you don't want to delete rows that are not returned if OBJECT_ID(N'usp_hkExtractHotData') IS NOT NULL drop procedure usp_hkExtractHotData go create procedure usp_hkExtractHotData @hotDate datetime with native_compilation, schemabinding, execute as owner as begin atomic with ( transaction isolation level = serializable, language = N'english' ) select id, orderDate, custName from dbo.hot where orderDate < @hotDate delete from dbo.hot where orderDate < @hotDate end go -- insert order -- inserts an order either in recent or older table, depending on the current hotDate -- it is important that the SP for retrieving the hotDate is repeatableread, in order to ensure that -- the hotDate is not changed before the decision is made where to insert the order -- note that insert operations [in both disk-based and memory-optimized tables] are always fully isolated, so the transaction -- isolation level has no impact on the insert operations; this whole transaction is effectively repeatableread if OBJECT_ID(N'usp_InsertOrder') IS NOT NULL drop procedure usp_InsertOrder go create procedure usp_InsertOrder(@id int, @orderDate date, @custName nvarchar(10)) as begin SET TRANSACTION ISOLATION LEVEL READ COMMITTED begin tran -- get hot date under repeatableread isolation; this is to guarantee it does not change before the insert is executed declare @hotDate datetime set @hotDate = (select hotDate from hotDataSplit with (repeatableread)) if (@orderDate >= @hotDate) begin insert into hot values (@id, @orderDate, @custName) end else begin insert into cold values (@id, @orderDate, @custName) end commit tran end go -- change hot date -- changes the hotDate and moves the rows between the recent and older order tables as appropriate -- the hotDate is updated in this transaction; this means that if the hotDate is changed by another transaction -- the update will fail due to a write/write conflict and the transaction is rolled back -- therefore, the initial (snapshot) access of the hotDate is effectively repeatable read if OBJECT_ID(N'usp_ChangeHotDate') IS NOT NULL drop procedure usp_ChangeHotDate go create procedure usp_ChangeHotDate(@newHotDate datetime) as begin SET TRANSACTION ISOLATION LEVEL READ COMMITTED begin tran declare @oldHotDate datetime set @oldHotDate = (select hotDate from hotDataSplit with (snapshot)) -- get hot date under repeatableread isolation; this is to guarantee it does not change before the insert is executed if (@oldHotDate < @newHotDate) begin insert into cold exec usp_hkExtractHotData @newHotDate end else begin insert into hot select * from cold with (serializable) where orderDate >= @newHotDate delete from cold with (serializable) where orderDate >= @newHotDate end exec usp_hkSetHotDate @newHotDate commit tran end go -- Deploy and populate tables -- cleanup delete from cold go -- init hotDataSplit exec usp_hkSetHotDate '2012-1-1' go -- verify hotDate select * from hotDataSplit go EXEC usp_InsertOrder 1, '2011-11-14', 'cust1' EXEC usp_InsertOrder 2, '2012-3-4', 'cust1' EXEC usp_InsertOrder 3, '2011-1-23', 'cust1' EXEC usp_InsertOrder 4, '2011-8-6', 'cust1' EXEC usp_InsertOrder 5, '2010-11-1', 'cust1' EXEC usp_InsertOrder 6, '2012-1-9', 'cust1' EXEC usp_InsertOrder 7, '2012-2-14', 'cust1' EXEC usp_InsertOrder 8, '2010-1-17', 'cust1' EXEC usp_InsertOrder 9, '2012-3-8', 'cust1' EXEC usp_InsertOrder 10, '2011-9-24', 'cust1' go -- Demo Portion -- verify contents of the tables -- hotDate is 2012-1-1 -- all orders from 2012 are in the recent table -- all orders before 2012 are in the older order table -- query hot data select * from hot order by orderDate desc -- query cold date select * from cold order by orderDate desc -- move hot date to Mar 2012 EXEC usp_ChangeHotDate '2012-03-01' -- Verify that all orders before Mar 2012 were moved to older order table -- query hot data select * from hot order by orderDate desc -- query old data select * from cold order by orderDate desc
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