Hi,Would like to know the performance differenece between Multi-columnIndex vs Single Column Indexes. Let's say I have a table with col1,col2, col3 along with a primary key column and non-indexed columns.In queries, I will use col1, col2, and col3 together and some timesjust one or two of these three columns. My questions is, should Icreate one index contains col1, col2, and col3, or create 3 seperatedcolumns. I.e. each column has its own index. Any performancedifference?Thanks a lot.
Okay this is a test...actually I am still learning SQL and need some help. Does anyone have any information on being able to move indexes from one database to another. My scenario is I have 3 databases, Development, QA and Production. I want to move/copy indexes I created in Development to the QA database. I have many indexes so I do not want to have to recreated them if I can avoid it. Any suggestions?
I have come across a problem executing a select with a multi-part where clause that only shows up if there are multiple indexes on the table. The situation using a simplified table is shown below
create table tblTest( utcTimestamp datetime NOT NULL, testType int NOT NULL)go
insert into tblTest (utcTimestamp, testType) VALUES('6/1/2003 0:0:0', 100)go
Now, without adding any indexes to the table, I can execute the following select and it works fine, returning the single row in 2003:
select * from tblTest where utcTimestamp < '1/1/2004 0:0:0' and utcTimestamp > '1/1/2003 0:0:0' and testType = 100go
Furthermore, if I introduce a single descending index on just the utcTimestamp:
CREATE INDEX IX_tblTest_Timestamp ON tblTest (utcTimestamp DESC)go
the search still works.
HOWEVER, if I now introduce another index:
CREATE INDEX IX_tblTest_EntryType_Timestamp ON tblTest ( testType, utcTimestamp DESC)go
the search does **not** return the row. However, if I change the where clause to remove the test of testType:
select * from tblTest where utcTimestamp < '1/1/2004 0:0:0' and utcTimestamp > '1/1/2003 0:0:0'go
it works.
Also, strangely, if I populate the table with a number of records with different dates and execute the following search:
select * from tblTest where utcTimestamp > '1/1/2004 0:0:0' and testType = 100go
I get records from **earlier** than 1/1/2004 (i.e. like the sense of the compare is wrong)
Finally, as I was writing this report, I discovered that all of these problems go away if the DESC is removed from the indexes - so that's my workaround, but it still looks like a bug.
The largest table in the database is not referenced by any other table. Primary key is identity column. I know that I shouldn’t make clustered index on that column, but what if I don’t index that column at all? Will it be some negative consequences of that decision?
Anyone can explain to me if the expression SELECT ... WHERE Column IN (..., ...) use the indexes or it's better to use the SELECT ... WHERE Column = ... OR Column = ...
I work in the healthcare area, and am handling the survey data ETL's. There are around 8 different survey areas and based on information received from them for the visit they reference, I want to pull in more info from our invoicing database. My idea is this:
1.) Pull in the flat file to an ODBC staging table 2.) Cache all invoice records that fall between the MIN(Date of Service) and MAX(Date of Service) from the staging table. 3.) First lookup the information needed on patientID, providerID, date of service, and billing location. 4.) For the surveys that didn't match on those 4 columns, try looking up based on patientID, date of service, and billing location (since I could be 99% sure this would still return the record I need). 5.) For the remaining surveys, lookup based just on patientID and date of service. These records will be flagged for manual review because clearly, if a patient has multiple appointments in the same day, this will be prone to error.
However, in trying to use only 3 of the columns in the lookup, I get the error saying basically that I need to utilize all 4. Is there a way around this, or is there an entirely different way I should be approaching this? The reason I thought cache transform was the answer is because I will need to run a different package for each lookup, as the data and logic between each survey will vary, but the invoice data "pool" will stay the same regardless.Â
Is there a way to compare tables in 2 different databases to find out if they have the same indexes and column names and keys. Or maybe a tool i dont know about.
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!
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.
I wanted to find all occurrences of ADRSCODE in a Database where ADRSCODE is in either an Index or a Primary Key.
I know how to get all of the occurences of ADRSCODE in a database and the table associated with it, I just want to tack on the Index and/or primary key.
I need to update multiple columns in a table with multiple condition.
For example, this is my Query
update Table1 set weight= d.weight, stateweight=d.stateweight, overallweight=d.overallweight from (select * from table2)d where table1.state=d.state and table1.month=d.month and table1.year=d.year
If table matches all the three column (State,month,year), it should update only weight column and if it matches(state ,year) it should update only the stateweight column and if it matches(year) it should update only the overallweight column
I can't write an update query for each condition separately because its a huge select
I have created a single FULLTEXT on col2 & col3. suppose i want to search col2='engine' and col3='toyota' i write query as
SELECT
TBL.col2,TBL.col3 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col2,'engine') TBL1 ON
TBL.col1=TBL1.[key] INNER JOIN
CONTAINSTABLE(TBL,col3,'toyota') TBL2 ON
TBL.col1=TBL2.[key]
Every thing works well if database is small. But now i have 20 million records in my database. Taking an exmaple there are 5million record with col2='engine' and only 1 record with col3='toyota', it take substantial time to find 1 record.
I was thinking this i can address this issue if i merge both columns in a Single column, but i cannot figure out what format i save it in single column that i can use query to extract correct information. for e.g.; i was thinking to concatinate both fields like col4= ABengineBA + ABBToyotaBBA and in search i use SELECT
TBL.col4 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col4,' "ABengineBA" AND "ABBToyotaBBA"') TBL1 ON
TBL.col1=TBL1.[key] Result = 1 row
But it don't work in following scenario col4= ABengineBA + ABBCorola ToyotaBBA
SELECT
TBL.col4 FROM
TBL INNER JOIN
CONTAINSTABLE(TBL,col4,' "ABengineBA" AND "ABB*ToyotaBBA"') TBL1 ON
TBL.col1=TBL1.[key]
Result=0 Row Any idea how i can write second query to get result?
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
I'm working to improve performance on a database I've inherited, and there are several thousand indexes. I've got a list of ones which should definitely exist within the database, and I'm looking to strip out all the others and start fresh, though this list is still quite large (1000 or so).
Is there a way I can remove all the indexes that are not in my list without too much trouble? I.e. without having to manually go through them all individually. The list is currently in a csv file.
I'm looking to either automate the removal of indexes not in the list, or possibly to generate the Create statements for the indexes on the list and simply remove all indexes and then run these statements.
As an aside, when trying to list all indexes in the database, I've found various scripts to do this, but found they all seem to produce differing results. What is the best script to list all indexes?
This is a report I'm trying to build in SQL Reporting Services. I can do it in a hacky way adding two data sets and showing two tables, but I'm sure there is a better way.
TheTable Order# Customer Status
STATUS has valid values of PROCESSED and INPROGRESS
The query I'm trying to build is Count of Processed and INProgress orders for a given Customer.
I can get them one at a time with something like this in two different datasets and showing two tables, but how do I achieve the same in one query?
Select Customer, Count (*) As Status1 FROM TheTable Where (Status = N'Shipped') Group By Customer
I have a stored proc I am updating in an OLEDB Command from the results of a Transform Script Component. The Stored Proc has over 65 input parameters, most of them have a NULL passed in. I dont want to create output columns in the Transform Script Component for all of them to map them from the "Available Input Columns" to "Available Destination Columns".
I want to create 3 or 4 generic Output columns for their data type - say IntegerOutput (datatype Int), DateTimeOut (datatype datetime) and so on. The I want to map these generic columns in the OLEDB Command as Available Input Columns" to multiple "Available Destination Columns" - wherever the datatype matches the input column.
But the OLEDB Command Column Mappings let me map One to One only. This will create a huge and unnecessary workload for me to develop and maintain - when I tell you I have 3 such stored procedures, all of whose interfaces are exactly same and for which I can create similar Output columns in the Transform Script Component.
I have a SQL Query issue you can find in SQL Fiddle
SQL FIDDLE for Demo
My query was like this
For Insert Insert into Employee values('aa', 'T', 'qqq') Insert into Employee values('aa' , 'F' , 'qqq') Insert into Employee values('bb', 'F' , 'eee') Insert into Employee values('cc' , 'T' , 'rrr') Insert into Employee values('cc' , 'pp' , 'aaa') Insert into Employee values('cc' , 'Zz' , 'bab') Insert into Employee values('cc' , 'ZZ' , 'bac') For select select col1,MAX(col2) as Col2,Max(Col3) as Col3 from Employee group by Col1
I am studying indexes and keys. I have a table that has a fixed width of data to be loaded in the first column which is parsed in a view based on data types within the fixed width specifications.
Example column A: (name phone house cost of house,zipcodecountystatecountry) -a view will later split this large varchar string based column b: is the source filename of the data load (varchar 256) ....
a. would there be a benefit of adding a clustered or nonclustered index (if so which/point in direction on why)
b. is there benefit of making one of these two columns a primary key (millions of records) or for adding a 3rd new column as a pk?
c. view: this parses the data in column a so it ends up looking more like "name phone house cost of house zipcode county state country" each having their own column.
-any pros/cons of adding indexes (if so which) to the view instead of the tables or both for once the data is parsed?
how to declare multiple derived columns in SSIS Derived Column Task in one attempt.as i have around 150 columns coming from Flat file. I had created the required Expression in Excel and now i want add those in derived column task but its allowing only 1 expression at a time.
So I'm reading http://www.sql-server-performance.com/tips/clustered_indexes_p2.aspx and I come across this: When selecting a column to base your clustered index on, try to avoid columns that are frequently updated. Every time that a column used for a clustered index is modified, all of the non-clustered indexes must also be updated, creating additional overhead. [6.5, 7.0, 2000, 2005] Updated 3-5-2004 Does this mean if I have say a table called Item with a clustered index on a column in it called itemaddeddate, and several non-clustered indexes associated with that table, that if a record gets modified and it's itemaddeddate value changes, that ALL my indexes on that table will get rebuilt? Or is it referring to the table structure changing? If so does this "pseudocode" example also cause this to occur: sqlstring="select * from item where itemid=12345" rs.open sqlstring, etc, etc, etc rs.Fields("ItemName")="My New Item Name" rs.Fields("ItemPrice")=1.00 rs.Update Note I didn't explicitly change the value of rs.fields("ItemAddedDate")...does rs.Fields("ItemAddedDate")=rs.Fields("ItemAddedDate") occur implicitly, which would force the rebuild of all the non-clustered indexes?
I need to query out multuple rows of data from the following table and retrieve it as a single row. Ideally, I'd like to do some sort of subquery that supports multiple columns, but as far as I know, that only exists on Oracle, not MSSQL. Here's an example of the data:UserDefinedFieldId UserDefinedRowID FieldValue1 1 date (stored as text)2 1 text3 1 text1 2 date (stored as text)2 2 text3 2 text...27 UserDefinedFieldIds for each row in the actual table I wrote a working query, but I need something more efficient for this particular application. (The query to do this must fit in a 2000char data field--with all 27columns brought in with separate subqueries, I'm pushing 5000.) Already tried shorter table names, which only saved me about a 1000 characters. SELECT (SELECT SecondaryTable.FieldValue FROM UserDefinedData AS SecondaryTable WHERE SecondaryTable.UserDefinedRowID = PrimaryTable.UserDefinedRowId AND SecondaryTable.UserDefinedFieldId = 1) AS Column1, ,,, (SELECT SecondaryTable.FieldValue FROM UserDefinedData AS SecondaryTable WHERE SecondaryTable.UserDefinedRowID = PrimaryTable.UserDefinedRowId AND SecondaryTable.UserDefinedFieldId = 27) AS Column27,FROM UserDefinedData AS PrimaryTableWHERE PrimaryTable.UserDefinedFieldId = 5 AND Cast(Cast(PrimaryTable.FieldValue AS varchar(64)) AS datetime) > GetDate() ORDER BY PrimaryTable.UserDefinedRowID, PrimaryTable.UserDefinedFieldId Any suggestions would be appreciated. Thanks, Brad
