Is there a way to drop clean buffers at the database level instead of the server/instance level like the undocumented €śDBCC FLUSHPROCINDB (@dbid)€??
Is there a workaround for €śdbo€? to be able to flush procedure and data cache without being elevated to €śsysadmin€? server role?
PS: I am aware of the sp_recompile option that can be used to invalidate cached execution plans.
Thx.
Hi,
My problem is that I cannot completely clean buffer cache on SQL Server 2005 version 9.00.2047.00 (probably SP1).
Right after I run DBCC DROPCLEANBUFFERS in the context of my database (this is development server, and so far I am only the one who is working with a particular database), I run a script that quetries sys.dm_os_buffer_descriptors view also from the context of my database to make sure that the buffer cache is really clean. However it shows large number of entries totalling 42 MB.
I ran both DBCC an the script in the past too, and it always showed nothing in the results, that means that buffers were really clean. The reason why I am running this is for benchmarking of existing and new application.
Does anybody have any idea, suggestions, how to troubleshoot this issue ? I already closed all connections to this database, but rebooting the server is not an option since other people are also working on it.
Thanks
What is the difference between CleanExpiredCache and FlushReportFromCache Do we need to run both the SPs to clear all the SSRS reporting cache? Is it possible to clean all the Cache information and retain the logs? If yes how we can do so. Is it by deleting the REportServerTempDB.dbo.ExecutionCache table work in achieving this?
View 8 Replies View RelatedHelp, have recently upgraded from 6.5 to 7.0 and have come across a problem with performance. The problem appears to relate to the buffer cache being flushed, the buffer cache hit ratio drops from 98% to 0% in a matter of a second. It then very slowly grows, then is flushed again, then increase slowly upto 30%.
Does any one have any ideas as to what would flush the buffer cache?
Any comments would be much appreciated - cheers
Does anyone know how to measure the buffer cache hit ratio? I have been reading a lot about it but can't find this measurement in Performance Monitor.
Thanks
What is better values for Buffer Cache Hot Ratio in SQL Server 2012. Is the values changed from 2008r2 to 2012?
View 2 Replies View RelatedI am wondering if 100% buffer cache hit ratio is considered not good in general?
Are there instances that it is actually bad and can contribute to server performance degradation?
Any thoughts on the topic most welcome :)
--------------------
keeping it simple...
This issue just happen recently. The buffer cache ratio went from > 90%to 50% and has slowly been climbing back up over 8 hours or so. Itscurrently @ 76%. Is this something I should take action on immediately?It seems to be coming back to normal...
View 1 Replies View RelatedHiI have trouble with MSSQL2000 SP4 (without any hotfixes). During last twoweeks it start works anormally. After last optimalization (about few monthsago) it works good (fast, without blocks). Its buffer cache hit ratio wasabout 99.7-99.8. Last day it starts work slow, there was many blocks anddedlocks. There are no any queries, jobs and applications was added. Nowbuffer cache hit ratio oscilate about 95-98. I try update statistics andreindex some hard used tables, but there is no effect or effect is weryshort (after few hours problem return).Mayby somene know what it could be?Is it possible to estimate how each table (using DBCC SHOW_STATISTICS orDBCC SHOWCONTIG or others) how the table affect on total buffer cache hitratio?Marek---www.programowanieobiektowe.pl
View 1 Replies View RelatedHello,
Does the performance counter Buffer cache object refer to Data cache and procedure cache or just refers to Data cache???
I was of the opinion that Buffer cache means data cache and Plan cache means procedure cache. Can someone throw some light???
Regards
Jaideep
We are troubleshooting a performance problem and the test result is slow the 1st time but the subsequent runs are faster.. Logging out of application and log back in ( connecting to a new database session) did not clear the buffer cache as I thought it would.. When does the database clear the buffer cache? Is it not per database session?
I can issue CHECKPOINT and then run DBCC DROPCLEANBUFFERS to clear the buffers in the disk. But since we are testing from the application,do we need to run these commands via application code to clear buffer/per database session OR can we run these commands from a management studio session?
I've a spatial (GIS) Data which is used frequently insertion, updation.
5 lakh records insertion in daily basis. when I trying to generate reports last 3 days or one weak, it takes 20-30 minute.
very disappointing while playing with clients. how to boostup and perform fast.
I think as so once we set query plan in buffer permanently then i would be faster than ever.
Im getting this error when trying to set up a cache dependency...are there any special permissions etc?From CS:SqlCacheDependency dep = new SqlCacheDependency("MySite-Cache", "Products");Cache.Insert("Products", de.GetAllProductsList(), dep); From connectionStrings.config:<add name="SiteDB" connectionString="Data Source=localhost,[port]SQLEXPRESS;Integrated Security=true;User Instance=true; AttachDBFileName=|DataDirectory|ASPNETDB.MDF" providerName="System.Data.SqlClient" />Also tried this using my machinename<add name="SiteDB" connectionString="Data
Source=<machinename>,[port]SQLEXPRESS;Integrated Security=true;User
Instance=true; AttachDBFileName=|DataDirectory|ASPNETDB.MDF"
providerName="System.Data.SqlClient" /> From web.config: <caching> <sqlCacheDependency enabled="true" pollTime="10000"> <databases> <add name="MySite-Cache" connectionStringName="SiteDB" pollTime="2000"/> </databases> </sqlCacheDependency> </caching> EDIT: So making progress I can't seem to get the table registered for cache dependency:The sample i have says"aspnet_regsql.exe -E -S .SqlExpress -d aspnetdb -t Customers -et"and the command line response is "Enabling the table for SQL cache dependency..An error has happened. Details of the exception:The table 'Customers' cannot be found in the database."Where does this "Customers" table come from? There is obviously not an application specific "Customers" table in aspnetdb I'm confused probably more by the example than anything....
I have a virtual server (VMware ESX) with 64GB RAM running a single instance of SQL 2012 SP1. The max memory config is set to 59392 (58GB).
The Page Life Expectancy for this server has been averaging well under 10 mins for the last few days, according to our monitoring.
I have been checking the amount of data in the buffer cache periodically during the day with the below query, which seems to show that there is never more than about 10GB of data at any one time, frequently dropping below 5GB:
SELECT COUNT(*) AS BufferPages,
CONVERT(decimal(10, 2), COUNT(*) / 128.0) AS BufferMB
FROM sys.dm_os_buffer_descriptorsWhy would the amount of cached data be so low (and cause so much churn)?
I am aware that other things will require some of that memory (plan cache etc.) but with Max Mem of 58GB, I would expect there to be a much higher amount of actual cached data at any one time. I did the same checks on another VM with the same amount of RAM/Max Mem setting, and there was 50GB of data in the cache, with PLE measured in hours.
I am using SQL 2012 and I am trying to find buffer cache usage by DB objects within a particular DB.
I am running the following query
select
name as DB,
objname as db_object_name,
COUNT(name) as cache_page_count,
COUNT('x')*8.0/1024 as size_mb
[Code] ....
Following are the results:-
DB db_object_name cache_page_countsize_mb
TEST_DBNULL 428 3.34375
TEST_DBsysobjvalues 369 2.882812
TEST_DBsyscolpars 44 0.34375
TEST_DBsysssislog 38 0.296875
....
.....
Question- Why am I getting 428 pages for which there is no corresponding DB object? Why are so many pages present in sys.dm_os_buffer_descriptors but are missing from sys.allocation_units.
I'm getting an alert which states that both my Buffer Cache Hit Ratio and PLE are low on one of my SQL Servers though I'm not sure how to correctly check this.
I ran:
SELECT object_name, counter_name, cntr_value
FROM sys.dm_os_performance_counters
WHERE [object_name] LIKE '%Buffer Manager%'
AND [counter_name] = 'Buffer cache hit ratio'
Which gives me the Buffer Cache Hit Ratio, cntr_Value of 9 though its constantly dipping between 3-3000 and is never steady and I'm unsure if this is normal.
I also ran:
SELECT object_name, counter_name, cntr_value
FROM sys.dm_os_performance_counters
WHERE [object_name] LIKE '%Buffer Manager%'
AND [counter_name] = 'Page life expectancy'
Which gives me the Page life expectancy of 209061.
If these values would cause concern and if this is a normal Buffer Cache Hit Ratio? It's constantly dropping from high or low from what I can see. These scripts were pulled from another forum and I'm assuming they're showing the correct values.
Our server administrator forwarded some messages from SCOM that indicate:
SQL DB Engine 2012 Page Life Expectancy and Buffer Cache Hit Ratio is too low
When I logged into the offending server, I could not find anything in the SQL Log File that indicates this.
I was wondering how did SCOM identify this issue - where in SQL Server would this have been reported to SCOM?
Hi guys,
I am looking at the plan caches/cached pages from the perspective of
sys.dm_os_memory_cache_counters and sql serverlan Cache - Cache Pages
For the first one I am using
select (sum(single_pages_kb) + sum(multi_pages_kb) )
from sys.dm_os_memory_cache_counters
where type = 'CACHESTORE_SQLCP' or type = 'CACHESTORE_OBJCP'
a slight change from a query in
http://blogs.msdn.com/sqlprogrammability/
For the second just perfmon.
The first one gives me a count of about 670,000 pages only for the object and query cache and the second one gives me a total of about 100,000 pages for five type of caches including object and query.
If I am using the query from http://blogs.msdn.com/sqlprogrammability/ to determin the plan cache size
select (sum(single_pages_kb) + sum(multi_pages_kb) ) * 8 / (1024.0 * 1024.0) as plan_cache_in_GB
from sys.dm_os_memory_cache_counters
where type = 'CACHESTORE_SQLCP' or type = 'CACHESTORE_OBJCP'
it gives me about 5 GB when in fact my SQL Server it can access only max 2GB with Total and Target Server Memory at about 1.5 GB.
Does anyone have any idea what is going on?
How do i check the size of the datacache allocated from the buffer pool by sql server?
DMV or anything to show me the pool allocation sizes for the various pools in sql server i think i may be able to work from there.
in microsoft doc there is written on the topic of BP Extensions with SSD's in SQL Server 2014: only clean pages are written to disk... does this mean data pages that have not been modified yet? or also those data pages that have already been modified, and where log has finished writing and the transaction has been marked as commited??
why are there clean data pages being written to L2 cache to make space for other not modified pages? I mean, shoudnt they be modified first, before letting other unmodified data pages into the Cache? I mean they have still to be modified..that makes no sense to me to page them out and page them in again just for other data pages...
I know this might be a dumb one, but what the heck. My new 7.0 server's procedure cache
stays at 100%. After researching this looks like what I want. Nay response appreciated.
Ours is a MSSQL Server Client server application with very minimal usage of Store procedures.
The proc cache is configured at 5%.I execute "dbcc proccache" to keep track of the proc cache.
I have seen that the "proc cache size" reduces to a very small a amount when there is peak usage.
It starts at 42,000 and comes down to 400, though it is always greater than "proc cache used".
I am worried if this causes crashes.
Please advise why this happens and solutions if any.
Thanks in advance,
Ramakrishna seelam.
Hello folks!
We are going to install SQL server 6.5 with MSMQ.
And set 128M memory for SQL Server.
What % Procedure cach do you recomend to set?
Thanks,
Alona
Hi Everybody!
In the application I have, database interaction is mainly through stored procedures.
Currently the setting for procedure cache is 30%. Does anyone have experience with having had changed this and effect on performance?
Thanks!
- Manoj
I have installed a SQL Server diagnose tool for evaluation. It prompts and warns me that "Procedure Cache hit rate is for example 15%. Its help indicates:
The Procedure Cache Hit Rate alarm is raised when the ratio between the number of times SQL Server looks for a plan in the procedure cache and the number of times it does not find a required plan in the procedure cache falls below a threshold.
A low procedure cache hit rate indicates that SQL Server is finding fewer of the query execution plans it needs already in memory and therefore has to perform more compiles. These extra compilations will degrade SQL Server performance by causing extra CPU load.
What can I do to increase the rate?
Canada DBA
Is any way we can tell sql server to keep specific (long runing) query in procedure Cache.
I already tried to do this by creating job (run every 1 hr from 8 am to 6 pm)
but is not enough
Thanks
Is there a way to increase the size of the procedure cache. Or is it only a auto configuring option.
I have 2gb of memory, and when I check the size of the procedure cache it is just 10mb. I would like to increase this to around 50mb. Not sure if there is an setting to do this. Had a look on BOL could not find anything.
thanks
Jane
I'm putting together some monitor scripts, have buffer cache ratio etc etc but struggling to get an accurate script for the current procedure cache hit ratio...
View 1 Replies View RelatedI have a 32 bit SQL 2005 EE clustered installation with 10GB of physical memory and AWE enabled. Our monitoring tool, Spotlight, is reporting the Procedure Cache to be 384MB and a Hit Rate of 75% on a fairly regular basis. Sometimes the Procedure Cache increases to 495MB and a Hit Rate of 82%.
(1) With 2005 can the Procedure Cache be increased?
(2) What is the max size of Procedure Cache?
(3) How do I increase the Hit Rate to a higher percentage?
I do not encounter the issue on any other SQL Server installation, however this is our only cluster.
DBCC PROCCACHE
num proc buffs = 64889
num proc buffs used = 1135
num proc buffs = 1135
active proc cache size = 2896
proc cache used = 364
proc cache active = 364
Thanks, Dave
Using SQL Server 2000. When does SQL flush or clear the procedurecache? I am dynamically creating and dropping stored procedures (SP).Does SQL clear the cache for the SP that has been dropped? If not,when the SP is recreated (with the same name), does SQL use theexecution plan from cache?Thank you in advance.Jack
View 2 Replies View RelatedMy server (SQL 2005 SP2) typically runs with a procedure cache usage of about 92% or higher... lately it seems like at some point in time during the day it just drops to anywhere between 50% and 65%... with this comes horrible server performance and many snowball effects. If I clear the procedure cache it will go up only about 10% for a minute or two. The only way I can get it to recover completely seems to be restarting the SQL service. Then it will be fine till the next incident. The database is a read only (not set to read only but no updates other than replication). and the same SPs are run over and over and over throughout the day. also did notice that the compiles of the SPs goes up drastically at this point also. not sure if this is part of the cause or part of the effect.
CPU is normal. response from anything (even sp_who) is slow.
i do not understand the way procedure cache works completely so I thought I would ask for some direction.
Any ideas where to look or where to start???
Any thing I can do to catch this when it happens would be great.
thanks a head of time.
Is there anyway to clear the procedure cache of a single procedure?
View 9 Replies View Relatedfrom BOL:
"
Restoring a database clears the plan cache for the instance of SQL Server.
"
i'm seeing this behavior after log restores as well.
what's the reason the whole procedure cache is flushed?
thanks.