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Insert sorted data to a table with nonclustered index


Insert sorted data to a table with nonclustered index

By : user2951957
Date : November 18 2020, 03:49 PM
like below fixes the issue The tree search cost is probably negligible compared to the cost of physical writing to disk and page splitting and logging.
1) You should definitely insert data in bulk, rather than row by row.
code :
CREATE TYPE [dbo].[PointValuesTableType] AS TABLE(
    point_id int,
    timestamp datetime,
    value int
)
CREATE PROCEDURE [dbo].[InsertPointValues]
    -- Add the parameters for the stored procedure here
    @ParamRows dbo.PointValuesTableType READONLY
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    BEGIN TRANSACTION;
    BEGIN TRY

        INSERT INTO dbo.point_log
            (point_id
            ,timestamp
            ,value)
        SELECT
            TT.point_id
            ,TT.timestamp
            ,TT.value
        FROM @ParamRows AS TT
        ORDER BY TT.point_id, TT.timestamp;

        COMMIT TRANSACTION;
    END TRY
    BEGIN CATCH
        ROLLBACK TRANSACTION;
    END CATCH;

END


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Nonclustered index with include vs nearly same Nonclustered index without; Multiple query coverage

Nonclustered index with include vs nearly same Nonclustered index without; Multiple query coverage


By : Tuan BA
Date : March 29 2020, 07:55 AM
should help you out Yes. #2 entirely covers #1 and possibly vice-versa in fact. Is pkTable your clustered index key? If so that will be included in #1 (at the key level because the non clustered index is not declared as unique).
If pkTable is not the clustering key then queries seeking on #1 will still be satisfied by #2 but #2 may occupy more pages thus making scans that would have used #1 a tad less efficient.
Can a query use more than one nonclustered index for a table?

Can a query use more than one nonclustered index for a table?


By : amucinom
Date : March 29 2020, 07:55 AM
To fix this issue I have a query that looks like this , Use a union. That is:
code :
SELECT TOP 1000 C.iId_company
FROM dbo.Company AS C WITH(NOLOCK)
WHERE 
C.col_1 LIKE 'something%'
OR C.col_1 LIKE 'something2%'
OR C.col_1 LIKE 'something3%'

union all 

SELECT TOP 1000 C.iId_company
FROM dbo.Company AS C WITH(NOLOCK)
WHERE 
C.col_2 LIKE 'something%'
OR C.col_2 LIKE 'something2%'
OR C.col_2 LIKE 'something3%'
Nonclustered Index Insert Showplan Operator - Missing?

Nonclustered Index Insert Showplan Operator - Missing?


By : Giovanni
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , You probably need to insert a greater number of rows to see the non clustered index maintenance shown as a separate operator.
You can either get a "wide" (per-index) or a "narrow" (per-row) plan.
code :
CREATE TABLE #T(
A INT CONSTRAINT PK PRIMARY KEY, 
B INT CONSTRAINT UQ UNIQUE) 


/*narrow plan*/
INSERT INTO #T 
SELECT 1,1

/*wide plan*/   
INSERT INTO #T 
SELECT DISTINCT number, number
FROM master..spt_values
WHERE number <> 1

DROP TABLE #T
Clustered and nonclustered index large data insert

Clustered and nonclustered index large data insert


By : Jon Coughlin
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , Unless it's a link table, you normally have clustered index on 1 column. And a general recommendation is to choose the smallest possible type for clustered index column(surely which fits your requirements). Having many columns not only increases size (each non-clustered index stores value of clustered index [includes clustered index]!), but also greatly increases chances of external fragmentation and degrading performance even of inserts . Thus, my answers to your questions.
That's correct, clustered index is a table, no need to include any columns Yes, absolutely I'm not sure what if you are asking about performance of switching itself or performance impact of having smaller(or fewer columns) clustered index, so I'll try to answer both. Switching itself. When you switch clustered index to non-clustered, I believe it should not be expensive (I don't think the engine will actually shuffle blocks and extents to make heap). Definitely IAM has to be changed which will take time. Changing non-clustered index to clustered involves much more activity. In addition to moving data according to clustered index key, SQLServer has to update all non-clustered indexes. Further impact (quite a large topic, I put a very short answer)... Smaller clustered index means less space needed for storing all other indexes which in turn means faster access to data and less resource consumption by the engine.
In a nonclustered index, how are the second, third, fourth ... columns sorted?

In a nonclustered index, how are the second, third, fourth ... columns sorted?


By : Mis012
Date : March 29 2020, 07:55 AM
With these it helps As a convenient shorthand, the keys of an index are used for the where clause up to the first inequality. like with a wildcard is considered an inequality.
So, the index will only be used for looking up the first value. However, the entries will probably be scanned to match on the first name, so you will still get index usage.
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