Columnstore Index Update

Introduction

The Columnstore Index Update is not really an actual operator. You can encounter it in graphical execution plans in SSMS (and other tools), but if you look at the underlying XML of the execution plan, you will see that it is actually either an Index Update or a Clustered Index Update operator.

SQL Server currently supports three types of index storage: rowstore, columnstore, and memory-optimized. Indexes of each of those types can be the target of an Index Update or a Clustered Index Update, as indicated by the Storage subproperty of the Object property. When the Storage property is RowStore or MemoryOptimized, then the normal Index Update or a Clustered Index Update icon is used, but when Storage is ColumnStore, and only a single index is listed in the Object property, then Management Studio and Plan Explorer show a different icon instead. (Azure Data Studio does show the regular icon for Index Update or a Clustered Index Update in these cases).

While clustered and nonclustered indexes each have their own operator for rowstore storage, these types are lumped together as a single icon and operator name in SSMS. Whether the targeted columnstore index is a clustered or a nonclustered index is only visible in parentheses behind the operator name (Clustered vs Nonclustered), or in the Logical Operation property (Clustered Index Update vs Index Update).

Visual appearance in execution plans

Depending on the tool being used, an Index Update or a Clustered Index Update operator with just a single update target that has its Storage property equal to ColumnStore is displayed in a graphical execution plan as shown below:

SQL Server Management Studio

Azure Data Studio

Plan Explorer

(version 17.4 and up)

(until version 17.3)

Icon for Columnstore Index Update in Management Studio (up to version 17.3)

n/a

PlanExplorer icon for Columnstore Index Update

Algorithm

The Columnstore Index Update is not a real operator but merely a visual indicator that an Index Update or a Clustered Index Update operator is modifying data in a columnstore index. Please check the appropriate pages for a full description of the algorithms of those operators.

Input or Seek Predicates

The generic description of the Clustered Index Update operator shows that the rows to be modified can be either provided by a child operator, or be defined in a Seek Predicate property. For the (nonclustered) Index Update, only the former method is supported.

A Columnstore Index Update also can only read rows from a child operator; a Seek Predicate property is not supported. This is true even when the target columnstore index is the clustered index. This makes sense when you realize that, due to their storage structure, seek operations are not possible on columnstore indexes.

The input rows will always contain a “ColStoreLocnnnn” input, which is a single internal value that represents the location of the row to be deleted. This “columnstore locator” is actually a combination of two values: the rowgroup number, and the ordinal position of the row within that rowgroup.

Operator properties

The properties below are specific to the Columnstore Index Update operator, or have a specific meaning when appearing on it. For all other properties, see Common properties. Properties that are included on the Common properties page but are also included below for their specific meaning for the Index Insert operator are marked with a *.

(Note that most of these properties are exactly the same as for the Index Update operator; they are repeated here for ease of use).

Property nameDescription
ActionColumnWhen this property is present, it lists the name of the column from the input that determines for each input row whether it updates existing data, inserts new data in the index, or deletes an existing row from the index.
When this property is missing, all input rows are considered to be an update to an existing row.
DMLRequestSortWhen set to true, the update operation might qualify for minimal logging if additional conditions apply. Details of those additional conditions and the requirements for DMLRequestSort to be true can be found here.
ObjectThe index that the Colummnstore Index Update operator will modify rows in, using four part naming (database, schema, table, index).
The subproperties of the Object property represent the four name parts separately, but also include two additional properties:
  • Index Kind: Represents what kind of index data is updated in. For a Columnstore Index Update, this can be ViewNonClustered (for nonclustered columnstore indexes on an indexed view), NonClustered (for all other nonclustered columnstore indexes), or Clustered (for all clustered columnstore indexes).
  • Storage: Determines the storage type of the index. For a Columnstore Index Update, this is always ColumnStore.
PartitionedWhen this property is present and set to true, the target of the Columnstore Index Update is a partitioned index.
PredicateMaps columns from the input stream to the columns in the index indicated by the Object property, or sets these columns to hardcoded values or variables from the query text.
WithOrderedPrefetchAs far as currently known, prefetching is never used (and hence this property never included) for a Columnstore Index Update operator.

Implicit properties

This table below lists the behavior of the implicit properties for the Columnstore Index Update operator.

Property nameDescription
Batch Mode enabledThe Columnstore Index Update operator supports row mode execution only.
BlockingThe Columnstore Index Update operator is non-blocking.
Memory requirementThe Columnstore Index Update operator does not have any special memory requirement.
Order-preservingThe Columnstore Index Update operator is fully order-preserving.
Parallelism awareThe Columnstore Index Update operator does not support parallelism. It can only be used in a serial plan, or in a serial section of a parallel plan.
Segment awareThe Columnstore Index Update operator is not segment aware.
Menu

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close