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Questions tagged [non-clustered-index]

Non-Clustered Index contains pointers to the data that is stored in the data page. In Non-Clustered Index logical order doesn’t match with physical order of stored data on disk.

Non-Clustered Index contains pointers to the data that is stored in the data page. In Non-Clustered Index logical order doesn’t match with physical order of stored data on disk. Non-clustered index contains index key to the table records in the leaf level. There can be one or more Non-clustered indexes in a table.

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SQL Performance, Execution plan showing mostly Index Scan instead of Index Seek

I am running below query, which is returning mostly 25 records. But it is taking almost 20 seconds. Also the total number of records in the table is less than 400,000. SELECT * FROM Tickets LEFT OUTER JOIN HouseAccounts ON (Tickets.lHouseAccount_ID…
Krunal
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Disabling non-clustered index on busy production database fails: Lock request time out period exceeded (Error: 1222)

I have a large and busy production database and I'm trying to tidy up the indexes that have accumulated over the years and reclaim some space. But I'm unable to drop/disable the existing indexes. They're all non-clustered yet disable fails with the…
Code Ninja
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Adding non-clustered index to a table to increase performance

I have table structure as below CREATE TABLE [dbo].[AIRQUALITYTS2] ( [FeatureID] [nvarchar](20) NOT NULL, [ParameterID] [nvarchar](20) NOT NULL, [MeasurementDateTime] [datetime2](7) NOT NULL, [ParameterValue] [numeric](38, 8) NULL, …
user641812
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How do indexes work behind the scenes

Im a begginer. I know indexes are necessary for performance boosts, but i want to know how they actually work behind the scenes. Beforehand, I used to think that we should make indexes on those columns which are included in where clause (which I…
Sadiq
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SQL Server Non Clustered Index creation timeout on large table (40 million rows)

Up until recently, I've been creating indexes (<20s) and running heavy queries (<10s) relatively quickly on a database containing tables that have up to about 10-12 million rows each. My newest database has tables with up to 40 million rows each and…
Cassie Lebauer
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Where clause on non-clustered index Vs extra join and where clause on clustered index

I am trying to eak out a bit extra performance from some sql queries which have a where clause on a field which is a non-unique non-clustered index, it is also a foreign key in table A. That foreign key is the primary key on table B and is the…
atamata
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Nonclustered primary key dilemma

Suppose we'd have to define optimal indexing for Stackoverflow questions. But let's not take the schema of the actual Posts table, let's just include those columns that are actually relevant: create table Posts ( Id int not null …
Robert Koritnik
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How to calculate the Num_Key_Cols for a Non-Clustered Index with included columns in it?

I'm trying to estimate the index size using the information provided at the MSDN website. Let us consider a table "Table1" with three columns in it. The columns are listed below, Id int, not null Marks int, not null SubmitDate Date, not…
RajeshKannan
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How NonClustered Index works in SQL Server

I have a question, related to DB theory: Let's assume that we have table with 3 columns: [PersonID], [PersonName], [PersonAge]. We know that when we have a nonclustered index by one column, SQL Server orders table data in accordance with specified…
Alex44
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SQL Server: NonClustered index not used

I have read a lot about indexing and differences between them. Now i am working on query optimization in my project. I have created nonclustered index, that should be used on query execution, but that is not the case. Details below: Table:…
bajicdusko
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Why RID (Bookmark) lookup is not being shown in execution plan?

I tried to examine RID (foremerly bookmark) lookup by creating a heap table: CREATE TABLE [dbo].[CustomerAddress] ( [CustomerID] [int], [AddressID] [int], [ModifiedDate] [datetime] ); GO CREATE NONCLUSTERED INDEX x ON…
Alireza
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Will DATE in primary key gain performance in range scans?

We have a large (and growing) MySQL db of bird records. At present we have three main tables, which simplified looks as follows: RECORDS (id, birdid, tripid, gender, age) PRIMARY KEY id BIRDTRIPS (id, locid, date, starttime, endtime, notes) PRIMARY…
Thomas Stjernegaard Jeppesen
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difference between creating index with two columns and creating separate index on two columns

What is the difference between creating index with two columns and creating separate index on two columns? Difference between create nonclustered index ix_index1 on table1(col1) create nonclustered index ix_index2 on table1(col2) and create…
Emman Bangis
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does non clustered index create a separate file to store its data?

I am really confused about the clustered and non clustered indexing and I have spent almost 5 hours today to clarify my doubt but I am still not able to find the answer of my following questions: 1- Clustered indexes are physically stored on table…
shruti angel
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Nonclustered index uses key into clustered index instead of address?

In the documentation for SQL server 2008 R2 is stated: Wide keys are a composite of several columns or several large-size columns. The key values from the clustered index are used by all nonclustered indexes as lookup keys. Any nonclustered indexes…
Ondrej Peterka
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