Pour les futurs étudiants du cours "MS SQL Server Developer", nous avons préparé la traduction d'un article utile.
Nous invitons également tout le monde à un webinaire ouvert sur le thème «Polybase: la vie avant et après» . Lors du webinaire, nous verrons comment il était possible d'interagir avec d'autres bases de données avant Polybase, et comment cela fonctionne maintenant.
: « SQL Server , ?»
, , , . . , : « — ».
, - Stack Overflow , :
USE StackOverflow;
GO
/* Create date partition function by day since Stack Overflow's origin,
modified from Microsoft Books Online:
https://docs.microsoft.com/en-us/sql/t-sql/statements/create-partition-function-transact-sql?view=sql-server-ver15#BKMK_examples
DROP PARTITION SCHEME [DatePartitionScheme];
DROP PARTITION FUNCTION [DatePartitionFunction];
*/
DECLARE @DatePartitionFunction nvarchar(max) =
N'CREATE PARTITION FUNCTION DatePartitionFunction (datetime)
AS RANGE RIGHT FOR VALUES (';
DECLARE @i datetime = '2008-06-01';
WHILE @i <= GETDATE()
BEGIN
SET @DatePartitionFunction += '''' + CAST(@i as nvarchar(20)) + '''' + N', ';
SET @i = DATEADD(DAY, 1, @i);
END
SET @DatePartitionFunction += '''' + CAST(@i as nvarchar(20))+ '''' + N');';
EXEC sp_executesql @DatePartitionFunction;
GO
/* Create matching partition scheme, but put everything in Primary: */
CREATE PARTITION SCHEME DatePartitionScheme
AS PARTITION DatePartitionFunction
ALL TO ( [PRIMARY] );
GO
Users, CreationDate:
DROP TABLE IF EXISTS dbo.Users_partitioned;
GO
CREATE TABLE [dbo].[Users_partitioned](
[Id] [int] NOT NULL,
[AboutMe] [nvarchar](max) NULL,
[Age] [int] NULL,
[CreationDate] [datetime] NOT NULL,
[DisplayName] [nvarchar](40) NOT NULL,
[DownVotes] [int] NOT NULL,
[EmailHash] [nvarchar](40) NULL,
[LastAccessDate] [datetime] NOT NULL,
[Location] [nvarchar](100) NULL,
[Reputation] [int] NOT NULL,
[UpVotes] [int] NOT NULL,
[Views] [int] NOT NULL,
[WebsiteUrl] [nvarchar](200) NULL,
[AccountId] [int] NULL
) ON [PRIMARY];
GO
CREATE CLUSTERED INDEX CreationDate_Id ON
dbo.Users_partitioned (Id)
ON DatePartitionScheme(CreationDate);
GO
INSERT INTO dbo.Users_partitioned (Id, AboutMe, Age,
CreationDate, DisplayName, DownVotes, EmailHash,
LastAccessDate, Location, Reputation, UpVotes,
Views, WebsiteUrl, AccountId)
SELECT Id, AboutMe, Age,
CreationDate, DisplayName, DownVotes, EmailHash,
LastAccessDate, Location, Reputation, UpVotes,
Views, WebsiteUrl, AccountId
FROM dbo.Users;
GO
Let’s c
Users Users_partitioned. , Users_partitioned , , , :
CREATE INDEX DisplayName ON dbo.Users(DisplayName);
CREATE INDEX DisplayName ON dbo.Users_partitioned(DisplayName);
, :
SET STATISTICS TIME, IO ON;
SELECT * FROM dbo.Users WHERE DisplayName = N'Brent Ozar';
GO
SELECT * FROM dbo.Users_partitioned WHERE DisplayName = N'Brent Ozar';
GO
, , , , 0% , — 100%:
, 0,001, — 15. , (compile time), (execution time) (logical reads) . , — ( ):
27 . , : « 27 ?» — ! , 250 . , . - .
, , ETL- . , 250 .
, ?
Users_partitioned . , ON PRIMARY , .
CREATE INDEX DisplayName ON dbo.Users(DisplayName); CREATE INDEX DisplayName ON dbo.Users_partitioned(DisplayName) ON [PRIMARY];
:
SET STATISTICS TIME, IO ON;
SELECT * FROM dbo.Users WHERE DisplayName = N'Brent Ozar';
GO
SELECT * FROM dbo.Users_partitioned WHERE DisplayName = N'Brent Ozar';
GO
:
- . , — :
, -
, , . (, rowstore- 100 ), , , . , , .
— , : «, , !» , : « , ».