SQL 2012 :: Drop All The Auto Generated Column Statistics?
Dec 29, 2014
My question: Is it okay to drop all the auto generated column statistics? (for the following scenario)
- I am cleaning up unnecessary objects (tables, unused indexes, overlapping statistics etc) from databases and found out there are more than 1400 auto generated column statistics on one database (lets call it A).
- Database A was used to be our reporting database but from last several years we are using database B for reporting. DB A has all the historical data while DB B only has valid records.
- We are updating all the column statistics with full scan nightly on database A and it is talking almost 2.5 hours to do that. Now I want to drop all the "unnecessary" statistics those were created when DB A was reporting database and they are no longer in use. There is no way to know the creation date of the column statistics that I know of. Statistics "last update date" is of no use because of our nightly job. So I was thinking of dropping all the auto generated column statistics and let the sql server create as it needs from now.
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Nov 21, 2014
We have implemented a very small reporting database which has a main table that started off small and has now grown to around half a million rows. Initially, there were no indexes on the table apart from a clustered index, but as the data has grown, performance has dropped and so we have added a number of indexes. This has resolved the performance issues.
Before creating the indexes SQL Server had auto created a number of statistic objects (_WA_Sys_000... etc). After creating the indexes, new statistic objects where created for the new indexes. In some cases, there are duplicate statistics (auto and index) for the same columns.Should I go through and drop the duplicate auto statistics? Will having duplicates cause issues at all?
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Aug 30, 2007
I need to know definitively when I need to drop and recreate column statistics (histogram) when altering a column. Empirically, it seems I can lengthen a varchar or change a not null column to a nullable one, and then existing statistics dont' cause
Msg 5074, Level 16, State 1, Line 1
The statistics 'c1' is dependent on column 'c1'.
Msg 4922, Level 16, State 9, Line 1
ALTER TABLE ALTER COLUMN c1 failed because one or more objects access this column.
But, if I change a column to not nullable or shorten a column, I get the error.
Is this the complete description of when I need to drop and recreate column statistics and when I don't?
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Jul 20, 2005
Hello group.I have an issue, which has bothered me for a while now:I'm wondering why the column statistics, which SQL Server wants me tocreate, if I turn off auto-created statistics, are so important to theoptimizer?Example: from Northwind (with auto create stats off), I do the following:SELECT * FROM Customers WHERE Country = 'Sweden'My query plan show a clustered index scan, which is expected - no indexexists for Country. BUT, the query plan also shows, that the optimizer ismissing a statistic on Country, which tells me, that the optimizer wouldbenefit from knowing this.I cannot see why? (and I've been trying for a while now).If I create the missing statistics, nothing happens in the query plan (andwhy should it?). I could understand it, if the optimizer suggested an indexon Country - this would make sense, but if creating the missing index, queryanalyzer creates the statistics with an empty index, which seems to me to beless than usable.I've been thinking long and hard about this, but haven't been able to reacha conclusion :) It has some relevance to my work, because allowing theoptimizer to create missing statistics limits my options for designingindexes (e.g. covering) for some rather wide tables, so I'm thinking why notturn it off altogether. But I would like to know the consequences - hopesomebody has already delved into this, and knows a good explanation.RgdsJesper
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Dec 18, 2012
I have a server which is not running optimally and I checked the default trace. I have around 600 entries in the default trace which are all Missing Column Statistics and the database is tempdb.is_auto_create_stats_on and is_auto_update_stats_on are both 1 for tempdb.
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Jul 23, 2014
Getting events in the default trace saying missing column statistics on a column...
1.The column is the primary key column ( identity )
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Feb 7, 2007
Hello,
I've a problem with auto-generated key. In my parent table, some lines have been deleted. I would like to add new lines with the same content in order to restore my database, but I cannot decide on the id value which is an auto-generated key. Is there a solution to set an auto-generated key with a specific value ?
Thank you in advance,
regards,
mathmax
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Feb 16, 2015
I am looking for standard sql code for below 2 concern.
1- I want to drop the column Rowchecksum to all the table where table name start with ArchiveBbx
2-I want to update all the table where table name start with ArchiveBbx
example:-
Update table Archivebbxfbcc
set Rowchecksum=HASHBYTES('MD5', CAST(CHECKSUM(Col001, Col002, Col003, Col004) AS varchar(max)))
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Apr 5, 2006
Hi all,
I'm using SQL 7, there is a setting on DB properties called "Auto update statistics", what kind of statistics does this refers to and how can this stats be accessed?
Thanks for your help!
Gustavo
Thanks,
GS
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Jun 20, 2007
I have Auto Create Statistics and Auto Update Statistics ON in one of my databases.
How do I know what time the Auto Update Statistics Kicks on ?
I dont see it in the log.
Is there a way for me to find out when was the last time Auto Update Statistics kicked on?
TIA
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Feb 3, 2008
Hello everyone,i have a web form to take user details.as soon as the submit button is clicked the form is submitting and the new row is being added into the sqldatabase.its fine ..but in the newly added row, i want the user id(primary key and auto generating) to display in different manner.in mytable column(userid),instead of userid auto displaying 1,2,3,4 ...i want it to display in this way.these are all primary keys of rows added.todaydate-username-1 eg(2.2.2008-jack-1)todaydate-usernaem-2 eg(2.2.2008-zak-2)todaydate-usernaem-3 eg(2.3.2008-leme-2)any idea how to achieve this.?thanks.jack.
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Oct 22, 2006
I downloaded the AdventureWorks OLTP Schema and am trying to use some of the design concepts that are used in this example but I don€™t quite understand some things.
First there is a column named rowguid, at the moment I assume that this is a GUID. If this is wrong most likely my next question will make no sense.
Second if that is indeed a guid all the tables have another id; example would be Employee table would have employeeid and rowguid, why do this? My best guess is that you would use the guid to easily insert (linked/sync) data into multiple tables without needing to retrieve the id from the table that was first input into. My scenario would be inserting an employee; to insert an employee you need to create a row in the employee, contact and address tables and for ease you would use the guid to link these rows. But if this is the case wouldn€™t there be sync issues that would arise?
If my guess is totally off please correct me also if anyone can direct me to some good resources that cover database design.
The schema can be downloaded at http://www.microsoft.com/downloads/details.aspx?familyid=0F6E0BCF-A1B5-4760-8D79-67970F93D5FF&displaylang=en#filelist
Thanks for any help.
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Sep 1, 2000
Hi everyone,
I know that statistics called _WA_... are created on tables when auto create statistics is set on a database. Is this an indication that queries against the table would perform better if indexes were created on the columns in question? (The tables I'm interested in optimising are used equally for transactional querying and reporting)
Thanks for any replies!
Les
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Dec 7, 2007
Hi all,
We are using SQL Server 2005. The auto update statistics and auto create statistics for a database is set to ON. This database has a very heavy work load. When I checked the individual statitics , still the last updated statistics is in a old date value (few months ago).
Is it necessary to manually update the statistics for the same database? Or can we rely upon "auto update statistics" itself ?
Usually in what frequency the manual UPDATE STATISTICS should be run on production system which has heavy transactions ?
Thanks & Regards,
Hariarul
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Jul 21, 2003
How to find out all the statistics from all the tables and drop them..any script anyone can help with?
When we are trying to make datatype changes in few related tables,it's giving error saying that some statistics are dependent onthe column blah blah...
Thanks,
Sheila.
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Aug 31, 2014
can i create Custom Auto-Generated Sequences with SQL Server like DD-0001,DD-0002,DD-0003...... to DD-000........
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Jan 9, 2007
Hey there :)I'm using Ruby on Rails to create a migration of a legacy database onan MS SQL Server. I'd like to name my constraints myself, such as'pk_authors', but in the cases where a table has an auto incrementedIDENTITY(1,1) id field, Rails takes over and adds the primary keyitself when creating the table.This is fine, except then the constraint gets a name like'PK__authors_384934' which is not very intuitive or easily remembered;)I'd like to just throw in an 'ALTER TABLE authors...' statement justafter that table has been created, but I'm not sure how to go aboutrenaming the auto generated constraint since the name it gets ispartially random. Is there any way to indirectly refer to theconstraint like 'RENAME PRIMARY KEY CONSTRAINT ON authors TOpk_authors' or something like that, so that I can rename theconstraint?Thanks in advance,Daniel Buus :)
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Feb 7, 2007
hi guys,
just a question regarding database design
i have a table with an auto-generated primary key but the problem is this:
say i have 4 records,so logically they'll be numbered 1 to 4.so the problem is whenever i delete all records and add new ones,the numbering will start from 5 and not 1 again.
how do i remedy this?
thanx
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Sep 12, 2007
Ok, let's say that I do a following inline INSERT statement.....
INSERT INTO Car ( carMake, carModel ) VALUES ( 'Honda', 'S2000' )
When I do this, a carId int value will automatically be generated because it is the Car table's PK and is an int identity. How do I obtain this value so I can immediately use it in let's say, the following example.
INSERT INTO Person ( carId ) VALUES ( @carId ) ..... where @carId is the value I need
Maybe you would say I should do something like.....
SELECT carId FROM Car WHERE carMake = 'Honda' AND carModel = 'S2000'
However, let's assume that the carMake and the carModel fields are NOT unique. I'm sure there's an easy way to extract the new identity value (maybe even in the same query) as the INSERT, but I just don't know how.
Thanks.
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Oct 20, 2007
Over the past week and a half we started experiencing a sporadic slowdown in our production x64 SQL 2005 Ent. Edition server. Users started complaining of slowness then they started getting timeouts. In looking at sp_who2 and perfmon we saw the following during the slow/frozen periods:
* Dramatic increase in Perfmon Active Transactions
* CPU higher than norm, but not dramatically so
* sp_who2 shows a number of spids in SUSPENDED state (and not running waits)
* no blocking indicated from sp_who2
* active connections slowly increasing
* no disk queuing (or at most some spikes to 1)
After a couple of minutes of this we would then see the following:
* no more spids in SUSPENDED state
* Logins per second spikes dramatically
* Active transactions spikes down to "normal levels"
* CPU goes high then levels out at moderately higher than normal
* active connections slowly decreases back towards normal levels
* large spike in lock wait time
We turned on the Async Auto Update Statistics option (after testing in our staging environment) on the primary database about a week before we saw this problem. By turning it off we can visually see the problem go away by watching the above metrics. So my question is, What metrics can I use to see the "blocking" or resouce locking that is causing these problems?
Anyone?
Thx
Ron
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Feb 16, 2014
Since upgrading from SQL Server Management Studio 2008 R2, I've noticed that it no longer autosaves queries that have not been manually saved first. If a file has been manually saved the autorecover files end up in the following directory:
%appdata%MicrosoftSQL Server Management Studio11.0AutoRecoverDatSolution1
However, I have ended up in the situation where I have unsaved queries when my computer has crashed and have not been able to recover them.
I have also found references to .sql files stored in temp files in the following directory, but the files here seem to be very haphazardly caught:
%userprofile%AppDataLocalTemp
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Jan 19, 2007
I have a field, userid, that somehow has the auto increment feature on it and I just want it to me a regular int field. How do i change it?
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Apr 17, 2014
statistics in sql server. how to create it and update it on tables.?
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Jun 5, 2014
I'm designing a new database which will be the back-end to a heavily-used web-based application (all these terms are relative - I guess the use won't be that heavy in the grand scheme of things, I'm only talking 100 users or so at the very most). Data from the old application database will be migrated to this one, and the old database is around 7GB in size after 5 years of use.
I have two different ways of linking some tables in mind, one which is slightly more complex than the other but which potentially has benefits over the simpler method. However, I'm concerned that I might be 'over-cooking' the design, and that performance would suffer as a result, so I've tried creating the two different versions of the database (the part of it I'm concerned with, anyway), one for each of the solutions I've got in mind, migrated the data into the relevant tables and carried out some queries on the data to collect some statistics.
The problem is that, whilst I can see that the more complex method is more expensive, as expected, I don't really understand if the difference is significant. Since I don't know what the numbers in the Client Statistics window actually mean (there are no units! I'm guessing times are in milliseconds?), or how much of real-world impact the difference will have, I'm finding it hard to interpret my statistics and come to a decision.
Querying the entirety of my tables to return ~20,000 records listing one column from each of the main tables I'm playing with, the simpler method had a Total Execution Time of 199, and the more complex a Total Execution Time of 272. Is that the statistic I should be most concerned with? Is that a difference I should be concerned about? Is the difference likely to be magnified when the database is much larger and in use, such that a difference of 73 milliseconds in this test scenario could end up being as much as a whole second in production, for example?
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May 20, 2014
I am working on an existing infrastructure and i do not have liberty to change much right now. I am in a situation where app issues update statistics command quite often. So frequently that sometimes one blocks another. Is there any way i can do something like this
IF ( update_statistics going on)
dont do anything
else
run update statistics
This is temporary solution untill i fix bad inline SQL code (in app) and use SPs.
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Jul 9, 2014
Seen activity like this? If so, where does it come from?
dd hh:mm:ss.mss:00 00:18:32.210
session_id:79
login_name:meme
wait_info:(6ms)IO_COMPLETION
CPU:646,180
tempdb_allocations:2,088
tempdb_current:0
blocking_session_id:NULL
reads:171,237,095
writes1,439,934
physical_reads:637,080
used_memory:2
status:rollback
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Feb 25, 2014
There are times when I either compile a stored procedure, or right now as I am creating indexes on tables, when sp_who2 shows a SPID assigned to my name that I do not currently have opened in SSMS. When I check the statement with dbcc inputbuffer it shows a query hitting many of the system views. Earlier this week, someone tried killing one of these SPIDS and SQL Server generated a new SPID with the same type of query.
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Apr 23, 2015
I have a sql query:
SELECT
'5' AS 'value/@version',
'database' AS 'value/@type',
'master' AS 'value/name',
LTRIM(RTRIM(( [Server Name] ))) AS 'value/server',
'True' AS 'value/integratedSecurity',
15 AS 'value/connectionTimeout',
4096 AS 'value/packetSize',
'False' AS 'value/encrypted',
'True' AS 'value/selected',
LTRIM(RTRIM(( [Server Name] ))) AS 'value/cserver'
FROM dbo.RedGateServerList
FOR XML PATH(''), ELEMENTS
I need to add some header information to the beginning of the query:
<?xml version="1.0" encoding="utf-16" standalone="yes"?><!--
SQL Multi Script 1
SQL Multi Script
Version:1.1.0.34--><multiScriptApplication version="2" type="multiScriptApplication"><databaseLists type="List_databaseList" version="1">
Everything I have tried ends up as a failure, usually compile issues. My goal here is to be able to automare a configuration file for multiscript so I can keep my server list up to date.
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Mar 12, 2008
I have this
use dbWebsiteLO
SELECT A.vehicleref,A.manufacturer,A.cvehicle_shortmodtext,A.derivative,min(a.ch) as price,A.capid,B.studioimages,(SELECT term FROM vwAllMatrixWithLombardAndShortModel WHERE vehicleref = a.vehicleref and ch = price) FROM vwAllMatrixWithLombardAndShortModel A
LEFT OUTER JOIN dbPubMatrix..tblCarImages B on A.capid = b.capid
WHERE a.source <> 'LOM' AND a.type = 'car' GROUP BY a.vehicleref,a.manufacturer,a.cvehicle_shortmodtext,a.derivative,a.capid,b.studioimages
I get Invalid column name 'price'. I'm trying to reference the "min(a.ch) as price"
Thanks
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Aug 19, 2015
I have been asked to create a report for one of our clients. The report is pretty basic but I am concerned about the overheads with my planned approach.The report is at a table and field grain to include values for:
* Min column value
* Max column value
* Number of discrete values
* Number of populated values (not NULL)
My current plan is to have a cursor over a limited view of sys.tables and sys.columns that will run a dynamic SQL query to import the results into a table that I can then output.There must be a better way of doing this and I don't have access to any DQS services.
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Mar 7, 2008
Hi I’m trying to alter a table and delete a column I get the following error. The object 'DF__Morningst__LastU__19EB91BA' is dependent on column 'LastUpdated'.
ALTER TABLE DROP COLUMN LastUpdated failed because one or more objects access this column. I tried deleting the concerned constraint. But the next time I get the same error with a different constraint name. I want to find out if I can dynamically check the constraint name and delete it and then drop the column. Can anyone help.IF EXISTS(SELECT 1FROM sysobjects,syscolumnsWHERE sysobjects.id = syscolumns.idAND sysobjects.name = TablenameAND syscolumns.name = column name)BEGIN EXECUTE ('ALTER TABLE tablename DROP CONSTRAINT DF__SecurityM__DsegL__08C105B8')EXECUTE ('ALTER TABLE tablenameDrop column columnname)ENDGO
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Jul 23, 2005
Hello,A script we run against the database as part of the upgrade of our productis failing with the following message:ALTER TABLE ALTER COLUMN EncodedID failed because STATISTICS hind_61_3accesses this columnThe line that fails is:alter table Badge alter column EncodedID nvarchar(16)It's clear that there's some kind of automatically generated statisticsobject referencing the column that prevents us from changing it from anint to an nvarchar. However, I have no idea how that got there - my bestguess would be that it has something to do with the auto generatestatistics option being set on the database. However that seems odd to mebecause we've done lots and lots of work like this and not encountered theproblem. It also seems like a quick fix would be to perform:Drop Statistics Badge.encodedidHowever I am afraid subsequent statements might fail on this db since Iwasn't really expecting this in the first place. Does anyone have anyinsight?Dave
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Oct 22, 2007
Hi,I'm constructing a query that will performs a lot o datetimecalculumns to generate columns.All that operations are dependent of a base calculum that is performedon the query and its result is stored in a columna returned.I wanna find a way of reusing this generated column, to avoidreprocessing that calculumn to perform the other operations, causethat query will be used in a critical application, and all saving isfew.Thanks a lot.
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