Unique Non-Clustered PK, Include Column(s)
Dec 6, 2007
Hello there,
I am testing out the performance benefits of utilizing include column(s) to avoid RID lookups and so far it looks very promising. I am able to reduce the cost of the query significantly and execution time is very good. However my non-clustered index is part of the primary key constraint and I am wondering if it is possible to create the include column as part of the primary key. Or do I have to drop the pk constraint and create unique non-clustered index with include column?
Thanks,
Sankar
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Apr 3, 2002
I have a database where records are Inserted by an external process.
There is no updating or deleting of the data once inserted. The table in
question has a Clustered Index on the Machine_ID (integer) (data is from
manufacturing processes). Each record bears a start and end time. Most
queries involve the Machine, a time span (start time between to points in
time), the Downtime Cause, and the Running Mode.
I want to add an index on the Start Time, the Downtime Cause, and the
Runtime Mode.
My question is: should this new index also contain the Machine_id column
or does the existence of the Clustered Index already on that column negate
its need in the new index?
RC - Dedicated to only creating original mistakes!
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Sep 4, 2015
We are going to use SQL Sever change tracking. The problem is that some of our tables, which are to be tracked, have no primary keys. There are only unique clustered indexes. The question is what is the best way to turn on change tracking for these tables in our circumstances.
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Oct 15, 2007
Hi everybody!
I just ran the Database Engine Tuning Advisor on a relative complex query to find out if a new index might help, and in fact it found a combination that should give a performance gain of 94%. Fair enough to try that.
What I wonder about: The index I should create contains 4 columns, the last of them being the Primary Key column of the table, which is also my clustered index for the table. It is an identity integer btw.
I think I remember that ANY index does include the clustered one as lookup into the data, so having it listed to the list of columns will not help. It might at worst add another duplicate 4 bytes to each index entry.
Right? Wrong? Keep the column in the index, or remove it since it is included implicit anyway?
Thanks for suggestions!
Ralf
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Aug 20, 2007
When not using any enforced relationships in a database (which I know we should, but I like most of you, have inherited sub-optimal design), is there any real difference between using a Primary Key (to which no foreign keys are tied) and using a Unique Clustered index?
Thanks for your thoughts
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Oct 31, 2015
Give a user table MyTable. How to know whether the table contains a non-unique clustered index by using SQL query?
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Oct 31, 2015
Give a user table ‘MyTable’. How to know whether the table contains a non-unique clustered index by using SQL query?
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May 30, 2008
I'm not able to create indexed views,
which are clustered-indexed on only 1st field.
I can't even INCLUDED other fields.
I need the entire view to exist as a physical table. (for performance)
Please let me know the work around.
Thanks..
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Mar 7, 2015
I have three sprocs and three tables. I was told to use a clustered index in the first table and a unique clustered index on the second table. I never asked about the third table and the person I need to ask is on vacation. Most of the contents of the first table will be joined with all of the contents of the second table into the third table. Do I need to have a unique clustered index on the third table too?
The clustered index in the first sproc is on a unique key that I had created using by concatenating several columns together.
CREATE CLUSTERED INDEX IX_UNIQUE_KEY ON MRP.Margin_Optimization_Data (UNIQUE_KEY);
CREATE NONCLUSTERED INDEX IX_DATE ON MRP.Margin_Optimization_Data (PERIOD);
CREATE NONCLUSTERED INDEX IX_ODS_ID ON MRP.Margin_Optimization_Data
(GL_SEG1_COMPANY_ODS_ID, GL_SEG2_PROFIT_CTR_ODS_ID, GL_SEG3_LOB_ODS_ID, GL_SEG4_PRODUCT_DEPT_ODS_ID, GL_SEG5_ACCOUNT_ODS_ID);
The second sproc with the unique clustered index is on the unique key from the first table and a date attribute.
CREATE UNIQUE CLUSTERED INDEX IX_UNIQUE_KEY ON MRP.[MGN_OPT_KPI_SOURCE] (UNIQUE_KEY, PERIOD);
In the third sproc, I'll have a nonclusted index on the ODS_ID attributes, but I'm unsure of how to go about the clustered index situation.
CREATE NONCLUSTERED INDEX IX_ODS_ID ON MRP.MGN_OPT_KPI_VALUES
(GL_SEG1_COMPANY_ODS_ID, GL_SEG2_PROFIT_CTR_ODS_ID, GL_SEG3_LOB_ODS_ID, GL_SEG4_PRODUCT_DEPT_ODS_ID, GL_SEG5_ACCOUNT_ODS_ID);
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Oct 30, 2015
Give a user table ‘MyTable’. How to know whether the table contains a non-unique clustered index by using SQL query?
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Jun 10, 2008
Dear All,
i've observed one particular table, one column is having clustered and non clustered index. is it ok? or i need to drop the non clustered column?
the table has 16 columns and at present 8 million records are there. per day approxmately 60000 rows will be getting into the table. it has another 3 non clustered indexes.
please suggest me.
Arnav
Even you learn 1%, Learn it with 100% confidence.
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Jul 30, 2007
GETDATE() works alone as default in a DateTime column, but:
1) How do you include current Date concatenated with text like:
- Column default Value = 'Submitted 2007-07-30 13:15:54.953'
2) is it possible to truncate that DateTime value (deleting the seconds 54.953)
- Final Column default Value = 'Submitted 2007-07-30 13:15'
Thinking Cast or convert but unsuccessful to date:
- 'Submitted ' + Cast(CHAR(16),GETDATE()) ???
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Jan 24, 2014
Reformatting data in a PIVOT Table or find a better way to display.
--ORDERDETAIL TABLE
SKUO QTYO ORDERIDO
KUM 1 12345
KUS 2 12345
SUK 1 12345
KHN 4 12345
DRE 1 12345
[Code] ....
Number of SKU's in order could be over 1000.
Looking to change my current pivot table to allow an unlimited number of SKU's and add QTY.
Data I am looking to get. MAX of 15 SKUS Per line.
ORDERID SKU1 QTY1 SKU2 QTY2 SKU3 QTY3 SKU4 QTY4 SKU5 QTY5 SKU6 QTY6 SKU7 QTY7 SKU8
QTY8 SKU9 QTY9 SKU10 QTY10 SKU11 QTY11 SKU12 QTY12 SKU13 QTY13 SKU14 QTY14 SKU15 QTY15
12345 KUM 1 KUS 2 SUK 1 KHN 4 DRE 1 HGF 2 FDE 1 CDS 1 GYT 1 POI 3 LKH 2 TTT 4 JHG 8 YUI 2 WQE 1
12345 PMN 1 BVC 1 ABD 1
[Code] ....
CURRENT PIVOT ONLY GOES TO 150 - BELOW
SELECT PKGCUSTOM4, [1] AS [SKU1], [2] AS [SKU2], [3] AS [SKU3], [4] AS [SKU4], [5] AS [SKU5], [6] AS [SKU6], [7] AS [SKU7], [8] AS [SKU8], [9] AS [SKU9], [10] AS [SKU10],
[11] AS [SKU11], [12] AS [SKU12], [13] AS [SKU13], [14] AS [SKU14], [15] AS [SKU15], [16] AS [SKU16], [17] AS [SKU17], [18] AS [SKU18], [19] AS [SKU19],
[Code] ....
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Jul 27, 2007
I have a table in which a non-primary key column has a unique index on it.
If I am inserting a record into this table with a duplicate column value for the indexed column, then what will be the error number of the error in above scenario? OR How could I find this out?
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May 1, 2015
I am having issues trying to write a query that would provide me the unique GUID numbers associated with a distinct PID if the unique GUID's > 1. To summarize, I need a query that just shows which PID's have more than one unique GUID. A PID could have multiple GUID's that are the same, I'm looking for the PID's that have multiple GUID's that are different/unique.
Table1
GUID PID
GUID1 PID1
GUID1 PID1
GUID1 PID1
GUID2 PID1
GUID3 PID2
GUID3 PID2
GUID3 PID2
The result of the query would only have PID1 because it has two unique GUID's. PID2 would not be listed has it has the same GUID3 in each row.
Result:
PID1
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Jul 23, 2005
Hello everyone, I am new to ERWIN and I need helps from the experts outthere.We are using ERWin 4.1.2771 and have reversed engineered some MS SQLServer 2000 databases.The problem we are having is that we have a FK on a column to a tablewhere the PK of the referencing table is on another column (such as anidentity column). We have a unique index on the column in the PK tableand SQL Server allows you to build a FK reference even though thecolumn is not defined as the PK.Does anyone know how to create this type of FK within Erwin?Thank You
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Nov 29, 2006
Here is my create table command
CREATE TABLE EXCLUSIVEITEM(VIEW_ID INTEGER NONCLUSTERED IDENTITY(1,1)PRIMARY KEY,
VIEW_LATEST_REPLY_DATE CLUSTERED INDEX DATETIME)
Is this the way to create one of my columns clustered. The books that I have all use stored procedure I only want to use regular sql commands. Is this possible?
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Jan 25, 2007
Users can approach their userprofile on my site using: www.mysite.com/name=peterName is a unique value within my database (db type: nvarchar(50))Now, I have created a clustered index on the username column.However, IMHO its faster to create a clustered index on the (also unique) usercode column since that is of type int.BUT since a user can approach my site based on username I feel that I HAVE to live with this setback in performance....Is that true or is there a better way to solve this issue?
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Apr 16, 2015
Is it always the best practice to have the partition column also as the column for clustered index?
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Jul 23, 2005
Is there any way to update a column in a clustered index without incurringthe cost of reordering.Example:Create table TableX (Col1 int,Col2 smalldatetime,Col3 varchar(10))gocreate clustered indext ix_test on tableX (Col2, Col1)goupdate TableX set Col2 = '2004-12-07'-- Yes I specifically left off the criteria to update every row.It would seem to me in this situation that the data types require the samestorage, all rows are being updated in one transaction, and there's no newto reorder since all will be the same.Thanks,Danny
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May 19, 2014
I am building three partitioned, clustered column store tables.I was researching whether it was faster to populate a staging table and swap it into the partitioned table or to directly insert into the partitioned table.The first partition for the three tables will have:
Table F: 50M rows, 6 columns wide, partitioned on a date column (1 date, 2 bigint keys, and two varchar columns)
Table D1: 50M rows, 150 columns wide, partitioned on a bigint
Table D2: 19M rows, 300 columns wide, partitioned on a bigint
If build the data that would go into partition 1 in a non partitioned column store, I get these table sizes:
Table F: 476 MB
Table D1: 6,800 MB
Table D2: 5,496 MB
If build the same data directly in the partitioned column store, my table sizes end up being:
Table F: 579 MB
Table D1: 6,800 MB
Table D2: 5,364 MB
That's a 20% difference on Table F, the narrow table.Looking at the row groups, I see 47 identical row groups in partition 1 and the unpartitioned table, but the average "size_in_bytes" is consistently 20% smaller in the unpartitioned table.
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Dec 24, 2014
I have 5 million rows of table, and going to create Non Clustered Index for Datetime values column. Creating Non clustered Index on Datetime value column will affect performance or not.
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May 29, 2007
Want to check my thinking with you folks...
I have a table with a clustered composite index, consisting of 3 columns, which together form a unique key. For illustration, the columns are C1, C2 & C3.
Counts of distinct values for columns are C1 425, C2 300,000 & C3 4,000,000
C3 is effectively number of seconds since 01/01/1970.
The usage of the table is typically, insert a row, do something else, then update it.
Currently, the index columns are ordered C3,C1,C2. Fill factor of 90%.
My thinking is that this composite index is better ordered C1,C2,C3.
My reasoning is that having C3 as the leading column, biases all the inserts towards one side of the indexes underlying B-tree, causing page splits. Also, there'll be a bunch of "wasted" space across the tree, as the values going into C3 only ever get bigger (like an identity), so the space due to the fill factor in lower values never gets used.
Welcome your thoughts.
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Oct 22, 2014
I need to find out all the tables in database, which has FK columns and don’t have any Non-clustered index on them.
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Apr 3, 2015
I've been asked to look at using Clustered Columnstore indexes for one of my tables. The table contains about 5 million records with about 50 columns. The max field size is a NVarchar(MAX) with max field length currently of about 4k characters. It's only about a gigabyte's worth of data. The table is about 50% R/W operations. Currently, we have multiple indexes with no clustered index due to some performance issues that happened in the past. I've been attempting to determine if it's even really worth it to switch over. I feel that the table is still fairly small with minimal columns and don't believe there will be any noticeable improvement over traditional indexing.
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Nov 24, 2015
I created composite clustered index key based on Gender and Salary column
The Query executed Successfully and <g class="gr_ gr_135 gr-alert gr_tiny gr_spell undefined ContextualSpelling multiReplace" data-gr-id="135" id="135">i</g>
got composite index key id Gender(-), Salary I <g class="gr_ gr_310 gr-alert gr_gramm undefined Grammar only-ins replaceWithoutSep" data-gr-id="310" id="310">want</g> know why Gender(-) display like this?
And Gender is <g class="gr_ gr_391 gr-alert gr_spell undefined ContextualSpelling ins-del multiReplace" data-gr-id="391" id="391">nvarchar</g> (20)
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May 18, 2015
I would like to put a Clustered Index on a date column in a current heap, but one question/concern.This heap every month has thousands of rows deleted and even more added later. How much of an issue will this cause the Clustered Index as far as page splits? I was thinking Fill Factor of 70%.I would normally just test and still will on Dev box, but my Dev box is much smaller than production as far as power.
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Jun 18, 2015
I have created NONCLUSTERED index on table but my report is taking more time that's why i created columnstore NONCLUSTERED index on the same table but i have one query, if any table have row and column level index(same columns in index) . Which index query will consider.
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Aug 2, 2015
I am extremely new to database design, and I ran into a problem that I know comes up often, however has many opinions...
Basically I have a table that is going to have 50+ columns. The natural key on this table is actually 8 columns wide, 4 of them being Varchar columns by default. (varchar(50)'s).
I have added an identity column, (1,1) to the table, however I put the clustered index on the 8 natural keys... My plan is to rebuild the clustered index once nightly when the system isn't in use (after 7 pm).
I know others would say it would be better to have the clustered key on the 1,1 column and then add indexes on the other 8 fields... However I don't quite understand why honestly...
Every single query against this table will use the 8 columns, and will NOT use the Identity column (1,1) because they are calls from other systems that do not know the Identity column....
Therefore if your database is set up for query speed, and every single query has to have a value for 8 columns to get a valid result, does it make sense to put a clustered index over the 8 columns?
If not why? Why is putting a clustered index on an identity column (that will literally never be used in a query) a better solution?
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Sep 27, 2015
I need to generate weekly report for data usage for my c drive and d drive.the graph should be likefor a particuluar date, I want to display graph like this. even if I change secondary axis, my c: drive used and free space not coming in single column. it comes like c: drive used space, on top of it d: drive used space and in adjacent column c: drive free space, on top of it d: drive free space.I don't want to add two category one for date and another for driver names.
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Feb 3, 2008
I am looking for advice on how to handle the following situation.Data being saved to a database table. Unique index on column in table. If the constraint is violated, what is the best way in alerting the user? Catch the exception and display error message to user? How do I know the exception is because of a unique index violation?
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Jul 11, 2004
Hi,
How can I assign or retrieve a unique ID from a msSQL table where there isn't a unique column.
Is there a hidden 'raw id' i can retrieve from msSQL for each record?
I'm not allowed to change the current database at all, but the developers who created it managed to use it without Unique IDs.... which doesn't help me coming from a mySQL background where UID's are kind of mandatory.
Thanks
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Sep 18, 2015
I have a database in which I have some tables in which I have implemented Clustered columnstore Index. How to find the fragmentation levels of all these indexes via a single T-SQl script
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