very slow query (select count(*) from table)

Daniel Wetzler

Dear MS SQL Experts,

I have to get the number of datasets within several tables in my MSSQL
2000 SP4 database.
Beyond these tables is one table with about 13 million entries.
If I perform a "select count(*) from table" it takes about 1-2 min to
perform that task.

Since I know other databases like MySQL which take less than 1 sec for
the same task
I'm wondering whether I have a bug in my software or whether there are
other mechanisms to get the number of datasets for tables or the number
of datasets within the whole database.

Can you give me some hints ?

Best regards,

Daniel Wetzler

Feb 15 '06 #1

Subscribe Reply

23704

joeNOSPAM

If you don't already have a unique index on this table, making an
index of that sort would help. The smaller the index (eg: on an int
column) the better.

Feb 15 '06 #2

Erland Sommarskog

Daniel Wetzler (Da************ @sig.biz) writes:

I have to get the number of datasets within several tables in my MSSQL
2000 SP4 database.
Beyond these tables is one table with about 13 million entries.
If I perform a "select count(*) from table" it takes about 1-2 min to
perform that task.

Since I know other databases like MySQL which take less than 1 sec for
the same task
I'm wondering whether I have a bug in my software or whether there are
other mechanisms to get the number of datasets for tables or the number
of datasets within the whole database.

To perform a query like SELECT COUNT(*), SQL Server will use the narrowest
non-clustered index to count the rows. If the table does not have any
non-clustered index, it will have to scan the table. Whether it is
reasonable with 1-2 minutes for 13 MB rows, depends on several factors.
But if the rows have a high average size, say 200 MB, and the table
also suffers fragmentation, then it is not unlikely. It also matter
whether the table already is in cache or not. If SQL Server has to read
all from cache it takes some time.

If you just want a quick number, you can do

SELECT rowcnt
FROM sysindexes
WHERE object_name(id) = 'tablename'
AND indid IN (9,1)
This number may not be fully accurate, but close enough.

--
Erland Sommarskog, SQL Server MVP, es****@sommarsk og.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pro...ads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinf...ons/books.mspx

Feb 15 '06 #3

Daniel Wetzler

Dear Erland and Joe,

thank you very much.
The select on sysindexes is a great advice and the best solution for
my
problem.

I tried another workaround yesterday :

I used the following statement :

select count(1) from table. (for tables with PRIMARY KEY in first
column)

It seems that MS SQL has to load the whole table information if I say
count(*).

Best regards and many thanks,

Daniel

Feb 16 '06 #4

Erland Sommarskog

Daniel Wetzler (Da************ @sig.biz) writes:

I used the following statement :

select count(1) from table. (for tables with PRIMARY KEY in first
column)
COUNT(1) or COUNT(*) makes no difference.
It seems that MS SQL has to load the whole table information if I say
count(*).

As I said, if there is no non-clustered table, there is no better
option than to scan all data pages.
--
Erland Sommarskog, SQL Server MVP, es****@sommarsk og.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pro...ads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinf...ons/books.mspx

Feb 16 '06 #5

Doug

i'll bite. why do you need to know the number of rows????

Feb 26 '06 #6

Similar topics

11110

Very slow distinct select

by: Rich | last post by:

My table looks like this: char(150) HTTP_REF, char(250) HTTP_USER, char(150) REMOTE_ADDR, char(150) REMOTE_HOST, char(150) URL, smalldatetime TIME_STAMP There are no indexes on this table and there are only 293,658 records total.

Microsoft SQL Server

2238

Very slow query - why?

by: Ben | last post by:

My question, pulled out of my source code comments: // This search is SLOW when WHERE is just zcustnum. This is inexplicable // to me, as the WHERE and ON conditions only reference zcustnum directly // in both tables, and in both instances there are btree indexes for them. // It seems to me that such a search ought to be almost instantaneous; the // ordered lists of zcustnum in the indexes should make the ON and WHERE // clauses...

PostgreSQL Database

1709

Very slow query

by: Rory Campbell-Lange | last post by:

The following query on some small datasets takes over a second to run. I'd be grateful for some help in understanding the explain output, and to remake the code. Looks like the sort is using up quite a bit of resources. I made an index on boards using columns "b.n_type, b.n_id, b.t_name" but the index was not recorded in explain analyze. (see "testindex" below). I am using PostgreSQL 7.4.2 on i386-pc-linux-gnu (Debian). The query is...

PostgreSQL Database

3603

very very slow query with parameters

by: aleicaro | last post by:

Hi, I have a problem with db2 query... I access to my database via jdbc using com.ibm.db2.jcc.DB2Driver. I build my string query in a java class. I have some parameters in my query, but there are two of these which gives me some problems: If I set the condition in the string: "...and myfield between 20001 and 20520..." all works properly. But if I want to set the values via parameters writing "...and myField between ? and ?..." and...

DB2 Database

4603

select count(table) problem

by: ret4rt | last post by:

Hello. I have a database with movies similar with imdb and i want to find out which directors have directed both thriller and drama movies. The output i want is like this "DIR_NAME,amount of thriller movies,amout of drama movies" First i did a check to see the expected number.Checkin only directors that have made thriller movies with select DIR_NAME, count(GENRE) from MGENRES, DIRECTORS, DIRECTED_BY where GENRE = 'Thriller' and...

Microsoft SQL Server

1319

Very Slow To Select Printer

by: =?Utf-8?B?VG9t?= | last post by:

I have a number of printers on my home office network, running XP Pro. Two are networked and the other two are parallel port. Everything works, but lately it seems like when I select a printer from the application (MS Word, Excel, etc. and QB 2007) it take forever to load the driver and get itself ready to print. Printing seems normal, but the software set up time seem much longer that before. Any ideas as to what may be going on would...

.NET Framework

1591

Problem with Query SELECT COUNT

by: viki1967 | last post by:

Hi. I have a table in a mysql db: NAME ROLE DATE TYPE MARK STR 2008-04-28 B KARL MAN 2008-04-28 A KARL IRE 2008-04-28 A

MySQL Database

1972

Slow Query causing application problems

by: dcharnigo | last post by:

Hi All, I am running a sql query from a web application. The web application timeout is set to 30 seconds and really should not be increased. I am running a very specific query . The table currently has 1 million rows and is growing everyday. The table is indexed but not on the guid field. Other queries return quickly but since this query is for only a single record based on the unique guid it is taking on average 45 seconds to return (when...

Microsoft SQL Server

8989

What is ONU?

by: marktang | last post by:

ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...

General

8828

Changing the language in Windows 10

by: Hystou | last post by:

Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...

Windows Server

9367

Maximizing Business Potential: The Nexus of Website Design and Digital Marketing

by: jinu1996 | last post by:

In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...

Online Marketing

9319

The easy way to turn off automatic updates for Windows 10/11

by: Hystou | last post by:

Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...

Windows Server

6073

Couldn’t get equations in html when convert word .docx file to html file in C#.

by: conductexam | last post by:

I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...

C# / C Sharp

4599

Trying to create a lan-to-lan vpn between two differents networks

by: TSSRALBI | last post by:

Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...

Networking - Hardware / Configuration

4869

Windows Forms - .Net 8.0

by: adsilva | last post by:

A Windows Forms form does not have the event Unload, like VB6. What one acts like?

Visual Basic .NET

3309

transfer the data from one system to another through ip address

by: 6302768590 | last post by:

Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system

C# / C Sharp

2213

Comprehensive Guide to Website Development in Toronto: Expert Insights from BSMN Consultancy

by: bsmnconsultancy | last post by:

In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

General