rebuild index sql server

I. Non-clustered index maintenanceThe row locator value for a nonclustered index keeps the same clustered index value, even after the clustered index column is physically relocated.To optimize this maintenance overhead, SQL Server

@parent =left (NEWID (), 40)EndInsert Mytesttable (id,parent) VALUES (@id, @parent)Select @[email protected]+1EndGoStep two, do not establish any index query tests/* Query when index is not established */DECLARE @beginTime datetime =getdate ()DECLARE @elapsedSecond int =0SELECT * from mytesttable where parent= ' dd7d9f34-3a9c-43ca-836b-f2babd78ce70 ' and id= ' 103ace5c-7 'Select @elapsedSecond =datediff (m

Summary of index, foreign key, and field syntax maintenance for mysql, SQL Server, and oracle databases, and SQL Server oracle Summary of index, foreign key, and field syntax maintenance for mysql,

Tags: style blog http io color ar os using SPOriginal: SQL Server index and table architecture (clustered index)Clustered indexOverviewThe concept of index and table architecture has always been the discussion of a lot of topics, including the table of various storage forms

Detailed description of SQL Server table and index storage structure, SQL Server This article analyzes in detail the principles of table and index structure storage in SQL

Some people may be confused with primary keys and clustered indexes. In fact, these two concepts are different. The following is a simple description. If you do not want to look at the context text, you can directly look at the comparison between the two. Especially the comparison of the last item. Primary Key) Description from msdn: A table usually has a column or a group of columns that uniquely identify the values of each row in the table. Such a column or multiple columns are called the prim

requirements. Because rebuild blocks all DML operations when online is not added.When we rebuild the index, Oracle directly reads the data from the original index if the online option is not added, and when we add the online option, Oracle is directly scanning the data in the tableWhen the

index statement must appear with the table or view, and you need to declare the table where the column resides (on). The following explains the effect of an option　　1, Asc/descThese two options allow you to select ascending and descending order for the index. The default option is ASC, which is ascending.Why do I need two options for ascending and descending? Not the reverse order to view the

when you create the table. CREATE TABLE Mytablekeyexample { int IDENTITY PRIMARY KEY nonclustered , int }　　　　 Once an index is created, the only way to change it is to delete and rebuild it, so it needs to be done right from the start. If you change the column in which the clustered index is located, SQL

not deleted during the creation of the new index until the new index rebuild successfully. From this you can know that rebuild than the removal of a reconstruction of the benefits of the original SQL query will not affect, but also because of this, the

Tags: Sele article results test data sequentially style str default test environmentRecently, some people have asked this question, has not been to delve into the joint index specific use of logic, consult multiple articles, and tested to draw some conclusions Test environment: SQL Server R2 The test results are similar to the MySQL Federated

1. What is the generation of index fragmentation? Index pages are split due to a large number of insert, modify, and delete operations in the table. If the index has high fragmentation, there are two situations: one is that it takes a lot of time to scan the index, and the other is that the

way to change it is to delete and rebuild it, so it needs to be done right from the start.If you change the column in which the clustered index is located, SQL Server will need to completely reorder the entire table (because the table has the same order and index order for

Joint primary key (joint index) Index Analysis in SQL Server (MySQL) Some people have recently asked this question, but they have not studied the specific use logic of the joint index before. They have read many articles and obtained some conclusions after tests. Test enviro

Tags: itblog custom function ANSI get TCA ORDER by how many ISS goodFirst, the basic concept of indexed viewsAn indexed view is actually a view that "materialized" a set of unique values into a clustered index, which is materialized almost as a table, and its data is stored in one copy (it consumes hard disk space, but the query is fast, for example, you can set count (), sum () in an indexed view). The advantage is that it provides a very quick way t

BuniessDateTime1 between ' 2016-6-21 ' and ' 2016-6-28 'There may be 10,000 data, then BUNIESSDATETIME2,BUNIESSSTATUS1, BUNIESSSTATUS2 filteringFinally, there is only one qualifying piece of data.The difference is that: at the beginning of the filter conditions, determine how many page queries to determine the initial criteria to meet the data, and then further filteringIf the data range that satisfies the query condition is determined relatively accurately at the very beginning, the data that