newsequentialid | 易学教程

Should a Sequential Guid primary key column be a clustered index?

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问题 The goal of using a sequential guid is so you can use clustered indexes without the high levels of fragmentation that would normally exist in a clustered index if it was a regular guid, correct? 回答1: Yes, you are correct. 回答2: First to clarify, a primary key and clustered index are 2 separate and distinct things, i.e. one is not coupled to the other (PKs can be nonclustered, clustered indexes can be non-PKs). That given, I think you're asking more "Should a Sequential GUID be used as a

Should a Sequential Guid primary key column be a clustered index?

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How to use NEWSEQUENTIALID() after a table has already been created and has data?

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问题 Could anyone help me with this please. I have a table that's not unique (as I'm rummaging through old databases of my predecessor.) I would like to assign it to the "ID" field within the Fruits table I have. I'd like to go ahead and get the NEWSEQUENTIALID() to be setup so I can see all what I'm working with. 回答1: Assuming ID is of type uniqueidentifier, you can create another column with sequential guids as default.This will populate the values in that column. After that you may copy these

How predictable is NEWSEQUENTIALID?

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问题 According to Microsoft's documentation on NEWSEQUENTIALID, the output of NEWSEQUENTIALID is predictable. But how predictable is predictable? Say I have a GUID that was generated by NEWSEQUENTIALID , how hard would it be to: Calculate the next value? Calculate the previous value? Calculate the first value? Calculate the first value, even without knowing any GUID's at all? Calculate the amount of rows? E.g. when using integers, /order?id=842 tells me that there are 842 orders in the application

Changing newid() to newsequentialid() on an existing table

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问题 At the moment we have a number of tables that are using newid() on the primary key. This is causing large amounts of fragmentation. So I would like to change the column to use newsequentialid() instead. I imagine that the existing data will remain quite fragmented but the new data will be less fragmented. This would imply that I should perhaps wait some time before changing the PK index from non-clustered to clustered. My question is, does anyone have experience doing this? Is there anything

Simplify SQL Insert which uses NEWSEQUNETIALID() column default

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问题 I have the following insert stored procedure: CREATE Procedure dbo.APPL_ServerEnvironmentInsert ( @ServerEnvironmentName varchar(50), @ServerEnvironmentDescription varchar(1000), @UserCreatedId uniqueidentifier, @ServerEnvironmentId uniqueidentifier OUTPUT ) WITH RECOMPILE AS -- Stores the ServerEnvironmentId. DECLARE @APPL_ServerEnvironment TABLE (ServerEnvironmentId uniqueidentifier) -- If @ServerEnvironmentId was not supplied. IF (@ServerEnvironmentId IS NULL) BEGIN -- Insert the data into

Creating unique groups in sequential data that repeats through time

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问题 This kind of thing has been asked before, but not quite in this way that I can find. Thread about creating sequential IDs, with several additional links It's not hard to create identifiers in a sequence, but my data includes a temporal element that has thrown me for a loop. The following data is an imaginary dataset just to illustrate the problem in something tractable: dput(walking_dat) structure(list(neighborhood = structure(c(3L, 3L, 3L, 3L, 3L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L), .Label = c(

NEWSEQUENTIALID() is broken in SQL Server for linux?

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问题 I am running MS SQL Server for linux from a Docker image (https://hub.docker.com/r/microsoft/mssql-server-linux/) I've discovered in my log files, that there are many PRIMARY KEY violations on my log table, which has ID uniqueidentifier DEFAULT NEWSEQUENTIALID() column. Exception is: Exception: System.Data.SqlClient.SqlException: Violation of PRIMARY KEY constraint 'PK_Logs'. Cannot insert duplicate key in object 'dbo.Logs'. The duplicate key value is (20c0423e-f36b-1410-8020-800000000000).

How predictable is NEWSEQUENTIALID?

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According to Microsoft's documentation on NEWSEQUENTIALID , the output of NEWSEQUENTIALID is predictable. But how predictable is predictable? Say I have a GUID that was generated by NEWSEQUENTIALID , how hard would it be to: Calculate the next value? Calculate the previous value? Calculate the first value? Calculate the first value, even without knowing any GUID's at all? Calculate the amount of rows? E.g. when using integers, /order?id=842 tells me that there are 842 orders in the application. Below is some background information about what I am doing and what the various tradeoffs are. One

NewSequentialId on UniqueIdentifier Clustered Index

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I am working on database standards for a new database my company is starting. One of the things we are trying to define is Primary Key and Clustered Index rules in relation to UniqueIdentifiers. (NOTE: I do not want a discussion on the pros and cons of using a UniqueIdentifier as a primary key or clustered index. There is a ton of info on the web about that. This is not that discussion.) So here is the scenario that has me worried: Say I have a table with a UniqueIdentifier as the clustered index and primary key. Lets call it ColA. I set the default value for ColA to be NewSequentialId().