% Performance Impact If Use Varchar Instead Of Char?
Feb 19, 2004Hi,
Anybody have any idea howmuch % of performance will be affect if we are using varchar instead of char data type?.
Thanks,
Ravi
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Datatype Question Varchar(max), Varchar(250), Or Char(250)
Oct 18, 2007
I have a table that contains a lot of demographic information. The data is usually small (<20 chars) but ocassionally needs to handle large values (250 chars). Right now its set up for varchar(max) and I don't think I want to do this.
How does varchar(max) store info differently from varchar(250)? Either way doesn't it have to hold the container information? So the word "Crackers" have 8 characters to it and information sayings its 8 characters long in both cases. This meaning its taking up same amount of space?
Also my concern will be running queries off of it, does a varchar(max) choke up queries because the fields cannot be properly analyzed? Is varchar(250) any better?
Should I just go with char(250) and watch my db size explode?
Usually the data that is 250 characters contain a lot of blank space that is removed using a SPROC so its not usually 250 characters for long.
Any insight to this would be appreciated.
SELECT INTO..# Performance Impact In SQL 7.0
Jan 18, 2001I want to determine the performance impact caused by the extensive use of the 'select into #' statement in a production environment. The current situation is that our reports team extensively uses the 'select into #' statement to build smaller subsets of data. These subsets are then used as the basis to create summary style reports and exports. All this is accomplished via the use of SQL pass-through.
After these reports/exports are completed and tested, they are then released to our operations department and the users. The reports/exports then can be run against the production server at the discretion of the user, provided they have the appropriate permissions. These reports/exports target the live data on the primary production server that already has been designated for the use of the application software.
Now I know that reporting against a transactional-based server, where the users run the application, is not a very good idea. (Inherited) I am currently migrating all reports/exports to a reporting server. Although it will still be transaction-based, the reports/exports will be isolated from user activity. Eventually we will be moving toward a warehouse scenario.
I also know that the extensive use of the 'select into #' statement is not a coding practice for use in production. I provided several alternatives to this practice
1) insert..select 2) insert..execute - from stored procedure
I have read that in the in sql 6.5 that this may cause severe performance and locking behaviors in system db's and tempdb. However, in the following document on the Microsoft Knowledge Base, it indicates that SQL 7.0 may have corrected this issue.
Q153441 - FIX SELECT INTO Locking Behavior.htm
Despite the indication of being corrected, I am still not convinced. I am frequently seeing drastic performance hits, especially when several of the reports are running. (which is very common) My concern is that moving these reports/exports to a reporting server may save the users; I believe that it may be migrating the problem to another location. I will be working with the developers to optimize their code and will investigate index issues.
** To make a long story short. I would like someone who has experience with this provide me with the top 5+ reasons not to use the 'select into #' methodology in a production environment. Further, if anyone has any documentation, I would surely like the info.
Thanks, Dave
Real Impact Of MS Performance Counters
Apr 18, 2008I have been collecting information about 20 performance counters (memory, IO, cpu, SQL) that refresh every 15 seconds, would that have any performance hit in the server? what are best practices when collecting information via performance counters?
Thanks
Performance Impact When Using On Delete Cascade
Jan 15, 2008I want to use "on delete cascade" in one of my tables but I'm worried though whether this can affect the performance when having millions of records. To explain more I'm working on a social networking website and I have two tables UserAccounts, in which I only keep the username and password and a few related fields, and Profiles in which I keep the profile data for users, I want to be sure that I won't have any records in the Profiles table without corresponding records in the UserAccounts table. Please see the DDL below to understand more the structure of the tables:
CREATE TABLE UserAccounts
(
UserID INT NOT NULL IDENTITY(1,1) PRIMARY KEY,
UserName VARCHAR(20) NOT NULL,
Password VARCHAR(20) NOT NULL,
--other fields (e.g. last login .. etc)
)
CREATE TABLE Profiles
(
UserID INT NOT NULL REFERENCES UserAccount(UserID),
-- other fields (e.g. birthdate, nationality .. etc)
)
Any suggestions are highly appreciated...
Impact Of Empty Tables On Database Size And Performance
Jun 21, 2007 Hello All,
When creating my database I have modeled some of the tables after the Adventureworks sample database.
There are some fields or entire tables in Adventureworks that I do not see an imediate use for, however; I would hate to ommit them to find out later they would have been benificial. (.eg territory table).
In general terms what would the impact be on size and performance of a database which contains tables or fields that do not contain data.
Thanks for your help!
Server Query Execution - Where Filtration Order - Performance Impact
Jul 27, 2015For example in a Select Statement we have many tables and we have Where Clause with many conditions with AND operations. Do the SQL SERVER would apply the Where clause after all fetch or can dynamically decide about to include the related Tables from Select Statement Orderly with respect to where clause predicates? (SQL SERVER would not fetch data of those tables for its Select, where the AND condition in Where clause fails or by logic would be fruitless/not-related.)
View 5 Replies View RelatedChar Vs Varchar
Dec 5, 2001Hi,
Does any body know of any performance implications of using 'varchar' data type against 'char'?
I have some columns that are using 'char' data type, but the data in them is not fixed length. So, to gain some disk space I am planning to change the data type to 'varchar'. But, I am concerned if there will be any performance de-gradation or any other implications of doing this.
Regards
Chakri
CHAR Vs VARCHAR
Mar 26, 2001Hi,
Is that true that using CHAR datatype improves the performance comparing to VARCHAR
thanks
indeed.
VARCHAR Vs. CHAR
Oct 27, 2000Why would you want to use char when you have varchar? Is there any performance hit using a varchar and the size you make that varchar?
Debate going at work.
Phil
Varchar V Char
Feb 17, 1999I have recently inherited a database where all of the tables use varchar instead of chars for fields. Very , very few of these fields are involved in keys of even indices, but performance is an issue. I thought that I had read that varchars are worse for performance than chars when page splits may occur. Is this related to updates only, or does it matter?
Any help appreciated.
Char (8) Vs. Varchar (8)
May 8, 2006In relation to the code in this thread
http://forums.databasejournal.com/showthread.php?t=42622
My customer code field is Char (8) but accept an argument of Varchar (8) to my stored procedure. Don't ask me why!?!!
The customer code could be anything from 'A' to 'ZZZZZZZZ'.
Will this have any effect especially relating to overhead and retrieving incorrect data?
Char Vs Varchar
Feb 21, 2006Hi,
This question may sound silly,but please comment.
Please tell me a situation where char should be used and not varchar.
Let us assume that we are dealing with non unicode characters.
Well, I find varchar is always smarter than char, so why char?
Thanks!!
Rudra
Varchar And Char
Feb 9, 2004i would like to know if there is an overhead in using VARCHAR when you use to store it...
a colleague of mine claims that if the field is defined to be VARCHAR the system creates and additional column DOUBLE/DECIMAL with storage size of 17/18bytes.
such that if the size of the varchar field is less than 30 it is better to be defined as CHAR instead.
please help me out here... i think there's something wrong with his statement, but i need concrete proof to it... a link to page or pdf file would be very much appreciated.
Char Vs. Varchar
Jul 23, 2005Greetings,I have a question. I work on some SQL2k/ASP.NET apps at work. Mypredacessor, who created the databases/tables seemed to have liked touse 'char' for all text fields. Is there a reason why he would havedone this over using varchar? It's a minor annoyance to always have toRTRIM data and it makes directly making changes to the database moreannoying (with all the pointless trailing spaces)?I usually use char for fixed string lengths, like state abbreviationsor something, and varchar for strings of unknown length.Is it a performance issue? Our database doesn't do much traffic, forthe most part.
View 5 Replies View RelatedNchar, Varchar,char?
Jan 11, 2008What is the difference between the above data types in SQL? Which datatype should I use if I wanted both numbers and characters?
View 1 Replies View RelatedChanged From Char To Varchar
Jun 3, 2004i changed my state table from char 20 to varchar 20 and it still fills it with empty space at the end of the statename
I tried entering it with the trim command still no good
i looked a the sql command made in vs and it says that the variables are varchar
is there something i am missing with varchar
does it only work properly if it is over 50 or does it not change completely when you change from char to varchar
VarChar Or Char Faster?
Mar 30, 2006Does using varchar or varchar(max) affect the system performance?
Should I use fixed size coloumns to increase speed?
Why Specify The Char Length In Varchar?
Feb 6, 2002Newbie question:
Why bother specifing the length in varchar()?
Why not just specify the max and not worry about truncation?
Thanks,
Martin
Difference Between CHAR And VARCHAR
Aug 8, 2002I have one question to all SQL Guru's
I know the basic difference between CHAR and VARCHAR of CHAR taking all the space it is declared with and VARCHAR taking only amount of space used.
I want to know or link to any doucment which gives the difference between CHAR and VARCHAR more than what is mentioned above.
Please this is a urgent requirment.
Thanks in advance.
Difference Between Char & Varchar
Nov 6, 2007what'z the difference between char & varchar, like i am doing a cast function, which one should be used..
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Aug 22, 2005helloHow could I check how many chars are in record, defined as varchar(8000).It's obvious that in such defined record could be 1 char to 8000 char. Butwhat query to SQL database should I post to give information about realylenght of this records ?thanks from advanceAdam
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May 28, 2007Hi,I'm planning the structure of a SqlServer 2005 database for a newapplication.The requirement is that primary keys must be "natural"; i.e. in the tableCustomers the primary key will be a max. 10 characters string (but thestring may be filled i.e. with only 5 charachters).Should I define these primary keys as char[5] or varchar[5]?I'm interested in your opinion in particular about performace issue, becausethere will be tables with millions of records...Thanks,Davide.
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Sep 7, 2007all these while i've only used varchar for any stringi heard from my ex-boss that char helps speed up searches. is thattrue?so there are these:1) char with index2) char without index3) char with clustered index4) varchar with index5) varchar without index6) varchar with clustered indexsome of my tables primary key (clustered) is a string type. would itbe benificial to use char? or would using (6) makes no difference?for non primary key columns that needs to be searched a lot, can i say(1) is the best?
View 4 Replies View RelatedSQL Variable Char Kinda Like Varchar
Jul 26, 2005Hi, is there a type of data that we don't need to specify the length but can grow dynamically?instead of using varchar 2000, a type that acts like a varchar but the length is unlimited ....Thanks,
View 5 Replies View RelatedConvert Varchar Or Char To Float
Jan 4, 2006Hello,
Is there a way to convert varchar or char to float?
Thank you
Nchar Or Char Or Nvarchar Or Varchar???
Apr 19, 2004Hi,
Which of the above data type (alongwith size) should be used for storing things like Customer Name, Company name etc . ???
Also, what really is the benefit of one over the over :confused:
Thanks
Can Varchar Length Be Set To More Than 8000 Char?
May 22, 2006Hi, everyone, I want to know is there a way for me to set varchar to store more than 8000 characters? (I did checked from sql server books online and i know that the maximum storage for varchar, but i just want to know is there any exceptional way for me to store more than that).
Thanks for any reply.
aex
Char Vs Varchar + Padding Issue
Feb 20, 2008I have upsized some tables from ms access (using the wizard) which has created many nvarchar fields. I know the system doesn't need unicode characters so I straight away changed them to varchar and the system is all working but am now deciding on which ones to change to char as I understand you get a performance gain. I am trying to do this without changing much ms access front end code so don't want to deal with rtrim I am thinking change the ones I can guarantee the length of. These happen to be the primary keys.
My questions are is this the correct way of doing things, am I correct in assuming I would have to rtrim alot in program code if I changed all to char.
Finally and. most importantly what about a single character field which could be null can I make this a char(1) and it will still return null if empty as it would as a varchar(1). I suppose this question is how does the padding work is it the character followed by a number of nulls (ascii 0 I think).
Sorry for the multiple questions but I think they are all related
Join Zero Padded Char To Varchar
May 31, 2008Having a brain fart and can't figure this out...I have 2 databases I need to join:db1.customer.customer_no char(15) right justified, zero paddedsample customer numbers:000000000000001000000000000010000000000000234000000000012345db2.customer.customer_no varchar(20) left justified, no paddingsample customer numbers:11023412345How do I join tables on customer_no? Use cast, convert? Strip zeroes fromdb1 table?Thanks.
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Dec 2, 2005can anybody please explain me why microsoft using nvarchar/nchar instead of varchar/char in northwind database and pubs database. I know if a column holds unicode data you should use nvarchar or nchar but for me all those tables in northwind/pubs are not holding unicode data. but still why microsoft settled for nchar/nvarchar.
View 2 Replies View RelatedData Types (char, Varchar, Nchar, Nvarchar, ...)
Jul 27, 2007Could someone please help me by explaining which one is best to use and when? For example, storing the word "Corona Del Mar" - which Data Type would be suggested?
Thanks.
Varchar Vs Char In 1st Field Of Composite Clustered Index
Jul 23, 2005Would it be OK to use varchar(5) instead of char(5) as the first field of acomposite clustered index?My gut tells me that varchar would be a bad idea, but I am not finding muchinformation on this topic on this when I Google it.Currently the field is Char(4), and there is a need to increase it to hold 5characters.TIA
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