clustered index

Therefore , even the non clustered indexes previously aligned with the clustered index , they may no longer be aligned with it .

The pointer from an index row in a non clustered index to a data row is called a row locator.

If a table has no clustered index , its data rows are stored in an unordered structure called a heap .

Intent Share locks on all clustered index pages containing those rows, unless the page is already protected by an IX lock.

The index key of a clustered index cannot contain varchar columns that have existing data in the ROW_OVERFLOW_DATA allocation unit.

The Argument column contains the bookmark label used to look up the row in the table or clustered index.

A view with a unique clustered index is called an indexed view.

For bulk importing into a table with a non-empty clustered index, the TABLOCK hint is ignored.

The only time the data rows in a table are stored in sorted order is when the table contains a clustered index.

If you chose to generate indexes in the wizard, a non-clustered index is generated for each of these relationship columns.

The Argument column also contains the name of the table or clustered index in which the row is looked up.

Only one clustered index can be dropped online at a time.

Therefore only one clustered index can be created on each table because the data rows themselves can only be sorted in one order.

If the clustered index is disabled, the CREATE INDEX WITH DROP_EXISTING operation must be performed with ONLINE set to OFF.

The index exploited for the inner table happens to be a clustered index.

Rebuilding a disabled clustered index cannot be performed with the ONLINE option set to ON.

Defines the steps and calculations needed to estimate the amount of space required to store the data in a clustered index.

In a clustered index, the physical order of the rows in the table is the same as the logical (indexed) order of the index key values.

When a table has a clustered index, the table is called a clustered table.

Calculate the space used to store index information for the clustered index.

Disabling a clustered index on a view does not prevent modifications to the underlying table.

A nonclustered index can be converted to a clustered index type by specifying CLUSTERED in the index definition.

Temporary disk space equal to the size of the existing clustered index is required to drop a clustered index.

Therefore, even if the nonclustered indexes were previously aligned with the clustered index, they may no longer be aligned with the heap.

A nonclustered index can be defined on a table or view with a clustered index or on a heap.

Columns; however, such columns cannot be included in the clustered index key.

As well, you can improve performance by creating a clustered index on a table.

The following example deletes a clustered index with a PRIMARY KEY constraint by dropping the constraint.

Index operations that create or rebuild an index, or that drop a clustered index, can be resource intensive.

Dropping a clustered index online requires as much space as creating a clustered index online.

The bottom, or leaf, level of the clustered index contains the actual data rows of the table.

Modifies more than one row and also updates the key of a nonunique clustered index to a nonconstant value.

Rebuilding a clustered index does not rebuild associated nonclustered indexes unless the keyword ALL is specified.

If the non clustered index is over a clustered index , the data row locator is the clustering key .

Heaps are tables that have no clustered index.

Rebuilding the clustered index on a view does not automatically enable nonclustered indexes on the view.

The first index created on a view must be a unique clustered index.

Reorganizing a specified clustered index compacts all LOB columns that are contained in the clustered index.

For more information about clustered index architecture, see Clustered Index Structures.

In a clustered index, the leaf nodes contain the data pages of the underlying table.

Thus, during the creation of a new clustered index, all operations on the table are blocked.

Generally, nonclustered indexes are created to improve the performance of frequently used queries not covered by the clustered index.

A column is part of a clustered index key that may be null.

They cannot be enabled until either the clustered index on the table or view is enabled or the clustered index on the table is dropped.

Points to the top of the clustered index B-tree in the specified partition.

For information about clustered indexes, see Clustered Index Design Guidelines.

A table or view is allowed one clustered index at a time.

Indicates whether the population involves a scan on the clustered index.

To reduce the extent fragmentation of a heap, create a clustered index on the table and then drop the index.

When you alter the clustered index of a table, however, the table must be locked in exclusive mode, because the data must be copied.

A unique clustered index must be created on a view before any nonclustered index is created.

Calculate the space used to store data in the leaf level of the clustered index.

However, if the offline filegroup contains the heap or clustered index of the target table, the SELECT statements fail.

More important, update the statistics on the clustered index or the full-text key for a full crawl.

for a clustered table , the row locator is the clustered index key.

The resulting clustered index will have the same name as the constraint.

Unable to define the clustered index.

How do I find all the tables that do not have a clustered index in a specified database?

There can only be one clustered index per table, because the data rows themselves can only be sorted in one order.

Unless a clustered index is explicitly specified, a unique, nonclustered index is created by default to enforce the UNIQUE constraint.

Nonclustered indexes must be explicitly enabled, unless the clustered index was enabled by using the ALTER INDEX ALL REBUILD statement.

Additionally , it rearranges the table rows so they appear in the order specified by the clustered index and primary keys .

Nonclustered or clustered index on the Name column.

Sp_updatestats ignores tables with a disabled clustered index.

If no location is specified and the table is not partitioned, the resulting table is included in the same filegroup as the clustered index.

You can reduce fragmentation and improve read-ahead performance by dropping and re-creating a clustered index.

If the nonclustered index is over a clustered index, the data row locator is the clustering key.

Unable to delete a clustered index.

Using the clustered index feature increases the chance that the two rows will appear on the same page in the database.

Scanning a clustered index, entirely or only a range.

Explains how data rows are stored in a clustered index and how they are accessed and maintained.

Disabling a clustered index prevents user access to the underlying table data.

Creating a unique clustered index on a view physically materializes the view.

Intent exclusive (IX) locks on the clustered index pages containing those rows.

In a clustered index, the leaf level contains the actual data pages of the table.

Data already sorted creates the clustered index with the SORTED_DATA option.

the pages of the heap or clustered index are managed in one or more allocation units , depending on the column types in the data rows.

The following example disallows page locks on a table with no clustered index (a heap).

Disabling a clustered index on a view physically deletes the index data.

After a unique clustered index has been created on a view, nonclustered indexes can be created.

There can be only one clustered index per table, because the data rows themselves can be sorted in only one order.

If the specified index is disabled, or the specified table has a disabled clustered index, an error message will be displayed.

Nonclustered indexes are automatically disabled when the associated clustered index is disabled.

This value does not include the leaf level of the clustered index.

If MOVE TO is not specified, the table will be located in the same partition scheme or filegroup as was defined for the clustered index.

Disabling a nonclustered index or clustered index on a view physically deletes the index data.

Use an integer data type for the first column of the clustered index.

Performance can be improved if the data being loaded is sorted according to the clustered index on the table.

A clustered index on a view must be unique.

Unable to build a clustered index.

This locator points to the data row in the clustered index or heap having the key value.

API cursor query contains a table with no clustered index or unique key.

For best performance, a CLUSTERED index is recommended.

If the clustered index is being rebuilt, an exclusive table lock is held.

Records in the clustered index contain fields for all user-defined columns.

Re-creating a clustered index reorganizes the data, and causes full data pages.

A clustered index must exist on the primary key of the user table.

A view must have a clustered index before statistics can be created on it.

Create the clustered index before creating any nonclustered indexes.

Rebuilding the index offline, by contrast, will force a scan of the clustered index (or heap) and so remove the inconsistency.

Is specified, DBCC CHECKTABLE runs integrity checks only on that index, together with the heap or clustered index.

Also changes when a clustered index on the table or view is created or altered.

Bulk-import the data with the clustered index already in place.

The clustered index if the pages are clustered index pages.

A clustered index or full-text key index on the table being indexed gets altered, dropped, or rebuilt.

A table without a clustered index.

Create a partitioned clustered index on a heap.

This includes the clustered index that contains the data rows of the table.

Reclaim space by creating a clustered index on the table or rebuilding an existing clustered index by using ALTER INDEX.

Bulk import performance is improved if the data being imported is sorted according to the clustered index on the table, if any.

Create a clustered index on the heap before deleting the rows.

Best Practice The order of data in the table is determined by the clustered index.

The heap of data pages if the pages are data pages in a table that does not have a clustered index.

After the unique clustered index has been created, you can create additional nonclustered indexes.

Updates a table containing a clustered index.

Initial unique clustered index on a view.

Disabling a clustered index on a view also disables any nonclustered indexes on that view.

Nonclustered or clustered index on the sorted or aggregated column.

Only one clustered index can exist per table.

A table can contain only one clustered index.

The clustered index is already defined.

A table is contained in one or more partitions and each partition contains data rows in either a heap or a clustered index structure.

Keep clustered index keys as small as possible.

Generally, you should define the clustered index key with as few columns as possible.

You can specify a unique clustered index if a clustered index on the table does not already exist.

A multirange crawl on a clustered index can produce the highest crawl speed.

Create the unique clustered index on the view.

A view that has a unique clustered index applied on it.

You index a view by creating a unique clustered index on it.

You can drop the clustered index after the rows are deleted.

Clustered tables are tables that have a clustered index.

One way is to create a partitioned clustered index on the table by using the CREATE INDEX statement.

There are several index options that can be specified when you create a clustered index.

This includes data pages in tables that have a clustered index.

Sp_autostats fails when the specified table has a disabled clustered index.

This redistributes the data while the clustered index is created.

A clustered index sorts and stores the data rows of the table or view in order based on the clustered index key.

A nonpartitioned clustered index and the base table always reside in the same filegroup.

This is significantly faster than creating the clustered index after the data is copied into the table.

Prefetching is used regardless of whether the table has a clustered index.

For example, creating a clustered index on an existing large table would benefit from the ONLINE index option.

A clustered index sorts and stores the data rows in the table based on the index key values.

The data rows are stored in order based on the clustered index key.

In SQL Server 2005, specifying TABLOCK on a table with a clustered index prevents bulk importing data in parallel.

This forces SQL Server to use a clustered index scan and find the data meeting the WHERE clause condition.

To create an indexed view, a unique clustered index is defined on one or more view columns.

No lock on the clustered index or table because they are already protected by IX locks.

You can rebuild a disabled nonclustered index online when the table does not have a disabled clustered index.

This problem occurs if the column is a clustered index key in Microsoft SQL Server 2000.

If the source table has a clustered index or if you intend to bulk import the data into a table with a clustered index

Incorrect Record is Deleted or Updated When a Clustered Index is in Descending Order

The following example returns total used pages and total number of rows for the heap or clustered index of the

Estimating the Size of a Clustered Index

ALTER INDEX REBUILD Disabled clustered index or disabled indexed view

Parallel Plan for Index Creation of Non-Clustered Index May Result in Use of Pages That are not Allocated

A view must meet the following requirements before you can create a clustered index on it

You can use the following steps to estimate the amount of space that is required to store data in a clustered index

You can implement one clustered index per table, using the following statements

Consider using a clustered index for queries that do the following

When the underlying table has no clustered index (that is, it is a heap) the settings are applied as follows

How to: Sort Data in a Clustered Index

Create a clustered index or recluster an existing index (new in 10. 00)