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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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Create a cover index with "Include" columns using nhibernate mapping file

I need to create a non-clustered index with INCLUDE columns (see the tag below). Here's the mapping file:
goku_da_master
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Why does SQL Server add a 4 byte integer to non-unique clustered indexes

It is possible to define non-unique columns as clustered as well as non-clustered indexes. However, SQL Server adds a 4 byte integer to the indexed columns in case of a clustered index, if the column is not defined as unique. This is done to keep…
SexyBeast
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Does Sybase have a index seek operation (like SQL Server) in exection plan?

I am SQL Server devloper who is trying to optimize a Sybase query. I am trying to get a non cluster index to seek, but it keeps doing scan, just wanted to confirm is "seek" possible in Sybase if yes how to acheve a non cluster index seek? I have a…
Pritesh
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SQL Server indexes cause conversion issue

I have a table with two columns - ID as int and date stored as nvarchar for some reason. A non-clustered index was recently created on the ID field. Now in my query, when I convert the date from nvarchar to date, it gives me an 'Arithmetic overflow…
etrast81
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sql differences between index fields and index with included fields

I was improving some sql query script's performance. For example: SELECT * FROM Book b, Library l, [Order] o WHERE o.bookid = b.bookID AND o.mode = 'A' AND o.library_ID = l.library_ID AND l.library_ID > 19 AND b.publisher_id > 1000 AND…
danmiao
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Create unique index with filter expression having IS NULL or OR

I am trying to develop a unique index. CREATE UNIQUE NONCLUSTERED INDEX NCI_NewUnique ON [NewUnique]([U1]) WHERE (ISNULL([MyField], '') = '') My error is Incorrect WHERE clause for filtered index 'NCI_NewUnique' on table 'NewUnique'. Here is…
Valamas
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Why doesn't innodb store row pointer in secondary/non-clustered index?

As we know, innodb stores only primary key value in its secondary index, which means we need to traverse the clustered index B+ tree again to fetch the row record. Why not just store the row pointer in secondary index to reduce the extra finding…
choxsword
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Why is SQL Server suggesting to include predicate columns in the INCLUDE of a new index?

I have a large query that I'm optimising and it requires an index. I created one that I thought was right, but SQL Server is telling me different. I have extracted the part of the query that needs the index and this sample produces the same index…
Murphybro2
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Getting Index Scan instead Index Seeking if IN clause larger in Azure Sql

This is the Non clustered index we have : ALTER TABLE [Allocation].[allocation_plan_detail] ADD CONSTRAINT [UQ_AP_TENANT_TYPE_STATUS_PLAN_ITEM_CLUB] UNIQUE NONCLUSTERED ( [tenant_id] ASC, [item_type] ASC, [allocation_plan_status] ASC, …
SUVAM ROY
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when exactly does a lock pseudo-record supremum occur?

I need a example, please What do you mean by applying the lock to a pseudo-record? https://dev.mysql.com/doc/refman/8.0/en/innodb-locking.html#innodb-next-key-locks For the last interval, the next-key lock locks the gap above the largest value in…
user19551894
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InnoDB Locking - Does record lock use indexes?

https://dev.mysql.com/doc/refman/8.0/en/innodb-locking.html#innodb-intention-locks Record Locks A record lock is a lock on an index record. For example, SELECT c1 FROM t WHERE c1 = 10 FOR UPDATE; prevents any other transaction from inserting,…
user19481364
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Can not add uniqueidentifier type column in columnstore non-clustered index

Im trying to create non-clustered COLUMNSTORE index on my fact table including some key columns.... but when selecting columns of table to add in index i don't see all of the columns which are uniqueidentifier type. There are all column types…
Vyacheslav Ratushnyy
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MySQL Clustered vs Non Clustered Index Performance

I'm running a couple tests on MySQL Clustered vs Non Clustered indexes where I have a table 100gb_table which contains ~60 million rows: 100gb_table schema: CREATE TABLE 100gb_table ( id int PRIMARY KEY NOT NULL AUTO_INCREMENT, c1 int, …
vrare
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SQL Indexing on uniqueidenfier column is not working

I am trying to put the index to a uniqueidentifier column. Here is the table schema and data: CREATE TABLE [dbo].[TestTable] ( [Id] [uniqueidentifier] ROWGUIDCOL NOT NULL, [ParentId] [uniqueidentifier] NULL, [Description] [varchar](50)…
Xylan Daniel
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Primary key is bigint and identity, any reasons for preferring non clustered index over clustered index

I've a table which is defined like this CREATE TABLE [dbo].[MyTable]( [MyTableId] [bigint] IDENTITY(1,1) NOT NULL, [SomeTable2Id] [bigint] NOT NULL, [SomeTable3Id] [bigint] NOT NULL, [SomeData] [smallint] NOT NULL, CONSTRAINT…
Ankush
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