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  • SQL SERVER – Guest Post – Jonathan Kehayias – Wait Type – Day 16 of 28

    - by pinaldave
    Jonathan Kehayias (Blog | Twitter) is a MCITP Database Administrator and Developer, who got started in SQL Server in 2004 as a database developer and report writer in the natural gas industry. After spending two and a half years working in TSQL, in late 2006, he transitioned to the role of SQL Database Administrator. His primary passion is performance tuning, where he frequently rewrites queries for better performance and performs in depth analysis of index implementation and usage. Jonathan blogs regularly on SQLBlog, and was a coauthor of Professional SQL Server 2008 Internals and Troubleshooting. On a personal note, I think Jonathan is extremely positive person. In every conversation with him I have found that he is always eager to help and encourage. Every time he finds something needs to be approved, he has contacted me without hesitation and guided me to improve, change and learn. During all the time, he has not lost his focus to help larger community. I am honored that he has accepted to provide his views on complex subject of Wait Types and Queues. Currently I am reading his series on Extended Events. Here is the guest blog post by Jonathan: SQL Server troubleshooting is all about correlating related pieces of information together to indentify where exactly the root cause of a problem lies. In my daily work as a DBA, I generally get phone calls like, “So and so application is slow, what’s wrong with the SQL Server.” One of the funny things about the letters DBA is that they go so well with Default Blame Acceptor, and I really wish that I knew exactly who the first person was that pointed that out to me, because it really fits at times. A lot of times when I get this call, the problem isn’t related to SQL Server at all, but every now and then in my initial quick checks, something pops up that makes me start looking at things further. The SQL Server is slow, we see a number of tasks waiting on ASYNC_IO_COMPLETION, IO_COMPLETION, or PAGEIOLATCH_* waits in sys.dm_exec_requests and sys.dm_exec_waiting_tasks. These are also some of the highest wait types in sys.dm_os_wait_stats for the server, so it would appear that we have a disk I/O bottleneck on the machine. A quick check of sys.dm_io_virtual_file_stats() and tempdb shows a high write stall rate, while our user databases show high read stall rates on the data files. A quick check of some performance counters and Page Life Expectancy on the server is bouncing up and down in the 50-150 range, the Free Page counter consistently hits zero, and the Free List Stalls/sec counter keeps jumping over 10, but Buffer Cache Hit Ratio is 98-99%. Where exactly is the problem? In this case, which happens to be based on a real scenario I faced a few years back, the problem may not be a disk bottleneck at all; it may very well be a memory pressure issue on the server. A quick check of the system spec’s and it is a dual duo core server with 8GB RAM running SQL Server 2005 SP1 x64 on Windows Server 2003 R2 x64. Max Server memory is configured at 6GB and we think that this should be enough to handle the workload; or is it? This is a unique scenario because there are a couple of things happening inside of this system, and they all relate to what the root cause of the performance problem is on the system. If we were to query sys.dm_exec_query_stats for the TOP 10 queries, by max_physical_reads, max_logical_reads, and max_worker_time, we may be able to find some queries that were using excessive I/O and possibly CPU against the system in their worst single execution. We can also CROSS APPLY to sys.dm_exec_sql_text() and see the statement text, and also CROSS APPLY sys.dm_exec_query_plan() to get the execution plan stored in cache. Ok, quick check, the plans are pretty big, I see some large index seeks, that estimate 2.8GB of data movement between operators, but everything looks like it is optimized the best it can be. Nothing really stands out in the code, and the indexing looks correct, and I should have enough memory to handle this in cache, so it must be a disk I/O problem right? Not exactly! If we were to look at how much memory the plan cache is taking by querying sys.dm_os_memory_clerks for the CACHESTORE_SQLCP and CACHESTORE_OBJCP clerks we might be surprised at what we find. In SQL Server 2005 RTM and SP1, the plan cache was allowed to take up to 75% of the memory under 8GB. I’ll give you a second to go back and read that again. Yes, you read it correctly, it says 75% of the memory under 8GB, but you don’t have to take my word for it, you can validate this by reading Changes in Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2. In this scenario the application uses an entirely adhoc workload against SQL Server and this leads to plan cache bloat, and up to 4.5GB of our 6GB of memory for SQL can be consumed by the plan cache in SQL Server 2005 SP1. This in turn reduces the size of the buffer cache to just 1.5GB, causing our 2.8GB of data movement in this expensive plan to cause complete flushing of the buffer cache, not just once initially, but then another time during the queries execution, resulting in excessive physical I/O from disk. Keep in mind that this is not the only query executing at the time this occurs. Remember the output of sys.dm_io_virtual_file_stats() showed high read stalls on the data files for our user databases versus higher write stalls for tempdb? The memory pressure is also forcing heavier use of tempdb to handle sorting and hashing in the environment as well. The real clue here is the Memory counters for the instance; Page Life Expectancy, Free List Pages, and Free List Stalls/sec. The fact that Page Life Expectancy is fluctuating between 50 and 150 constantly is a sign that the buffer cache is experiencing constant churn of data, once every minute to two and a half minutes. If you add to the Page Life Expectancy counter, the consistent bottoming out of Free List Pages along with Free List Stalls/sec consistently spiking over 10, and you have the perfect memory pressure scenario. All of sudden it may not be that our disk subsystem is the problem, but is instead an innocent bystander and victim. Side Note: The Page Life Expectancy counter dropping briefly and then returning to normal operating values intermittently is not necessarily a sign that the server is under memory pressure. The Books Online and a number of other references will tell you that this counter should remain on average above 300 which is the time in seconds a page will remain in cache before being flushed or aged out. This number, which equates to just five minutes, is incredibly low for modern systems and most published documents pre-date the predominance of 64 bit computing and easy availability to larger amounts of memory in SQL Servers. As food for thought, consider that my personal laptop has more memory in it than most SQL Servers did at the time those numbers were posted. I would argue that today, a system churning the buffer cache every five minutes is in need of some serious tuning or a hardware upgrade. Back to our problem and its investigation: There are two things really wrong with this server; first the plan cache is excessively consuming memory and bloated in size and we need to look at that and second we need to evaluate upgrading the memory to accommodate the workload being performed. In the case of the server I was working on there were a lot of single use plans found in sys.dm_exec_cached_plans (where usecounts=1). Single use plans waste space in the plan cache, especially when they are adhoc plans for statements that had concatenated filter criteria that is not likely to reoccur with any frequency.  SQL Server 2005 doesn’t natively have a way to evict a single plan from cache like SQL Server 2008 does, but MVP Kalen Delaney, showed a hack to evict a single plan by creating a plan guide for the statement and then dropping that plan guide in her blog post Geek City: Clearing a Single Plan from Cache. We could put that hack in place in a job to automate cleaning out all the single use plans periodically, minimizing the size of the plan cache, but a better solution would be to fix the application so that it uses proper parameterized calls to the database. You didn’t write the app, and you can’t change its design? Ok, well you could try to force parameterization to occur by creating and keeping plan guides in place, or we can try forcing parameterization at the database level by using ALTER DATABASE <dbname> SET PARAMETERIZATION FORCED and that might help. If neither of these help, we could periodically dump the plan cache for that database, as discussed as being a problem in Kalen’s blog post referenced above; not an ideal scenario. The other option is to increase the memory on the server to 16GB or 32GB, if the hardware allows it, which will increase the size of the plan cache as well as the buffer cache. In SQL Server 2005 SP1, on a system with 16GB of memory, if we set max server memory to 14GB the plan cache could use at most 9GB  [(8GB*.75)+(6GB*.5)=(6+3)=9GB], leaving 5GB for the buffer cache.  If we went to 32GB of memory and set max server memory to 28GB, the plan cache could use at most 16GB [(8*.75)+(20*.5)=(6+10)=16GB], leaving 12GB for the buffer cache. Thankfully we have SQL Server 2005 Service Pack 2, 3, and 4 these days which include the changes in plan cache sizing discussed in the Changes to Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2 blog post. In real life, when I was troubleshooting this problem, I spent a week trying to chase down the cause of the disk I/O bottleneck with our Server Admin and SAN Admin, and there wasn’t much that could be done immediately there, so I finally asked if we could increase the memory on the server to 16GB, which did fix the problem. It wasn’t until I had this same problem occur on another system that I actually figured out how to really troubleshoot this down to the root cause.  I couldn’t believe the size of the plan cache on the server with 16GB of memory when I actually learned about this and went back to look at it. SQL Server is constantly telling a story to anyone that will listen. As the DBA, you have to sit back and listen to all that it’s telling you and then evaluate the big picture and how all the data you can gather from SQL about performance relate to each other. One of the greatest tools out there is actually a free in the form of Diagnostic Scripts for SQL Server 2005 and 2008, created by MVP Glenn Alan Berry. Glenn’s scripts collect a majority of the information that SQL has to offer for rapid troubleshooting of problems, and he includes a lot of notes about what the outputs of each individual query might be telling you. When I read Pinal’s blog post SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28, I noticed that he referenced Checking Memory Related Performance Counters in his post, but there was no real explanation about why checking memory counters is so important when looking at an I/O related wait type. I thought I’d chat with him briefly on Google Talk/Twitter DM and point this out, and offer a couple of other points I noted, so that he could add the information to his blog post if he found it useful.  Instead he asked that I write a guest blog for this. I am honored to be a guest blogger, and to be able to share this kind of information with the community. The information contained in this blog post is a glimpse at how I do troubleshooting almost every day of the week in my own environment. SQL Server provides us with a lot of information about how it is running, and where it may be having problems, it is up to us to play detective and find out how all that information comes together to tell us what’s really the problem. This blog post is written by Jonathan Kehayias (Blog | Twitter). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Le pluriel dans les traductions avec Qt, un article de Jan-Arve Sæther traduit par Jonathan Courtois

    Bonjour, Dans la continuité des traductions des Qt Quarterly, je vous propose aujourd'hui un article expliquant comment gérer au mieux les formes du pluriel des différentes langues dans vos traductions. Les formes du pluriel dans les traductions Aviez-vous déjà connaissance de ces subtilités ? Cet article va-t-il améliorer la qualité des traductions de vos applications ?...

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  • PCSX2 1.0.0 installation issues

    - by user205261
    I've followed all the tutorials I can find to get this emulator to work and I'm now getting this error. Granted I've gotten a lot further than when I started. Running 13.10. Just downloaded the Linux download file from the pcsx2 website and did the following in terminal: jonathan@Assassin:~$ sudo add-apt-repository ppa:gregory-hainaut/pcsx2.official.ppa [sudo] password for jonathan: The Official pcsx2 ppa, provided by the pcsx2 team. This ppa contains a regular package snapshot of pcsx2. We are not package experts, but we try to follow the debian policy. Press [ENTER] to continue or ctrl-c to cancel adding it gpg: keyring `/tmp/tmpe5fwdz/secring.gpg' created gpg: keyring `/tmp/tmpe5fwdz/pubring.gpg' created gpg: requesting key 7A617FF4 from hkp server keyserver.ubuntu.com gpg: /tmp/tmpe5fwdz/trustdb.gpg: trustdb created gpg: key 7A617FF4: public key "Launchpad official ppa for pcsx2 team" imported gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1) OK jonathan@Assassin:~$ sudo apt-get update Err http://ppa.launchpad.net saucy/main amd64 Packages 404 Not Found Err http://ppa.launchpad.net saucy/main i386 Packages 404 Not Found Fetched 67.4 kB in 16s (3,977 B/s) W: Failed to fetch ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found W: Failed to fetch ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found E: Some index files failed to download. They have been ignored, or old ones used instead. jonathan@Assassin:~$ sudo apt-get install pcsx2 Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package pcsx2 So I'm assuming I just need the way to get the two missing packages?

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  • Apple Script error: Can't get Folder

    - by Jonathan Hirsch
    I started using apple script today, because I wanted to be able to automatically send files to someone when they go into a specific folder. I first tried with automator, but the files were never attached into emails, so i figured i could try with apple script. At first, I tried simply create an email with an attached file. The email was created, but the file was not attached. After a while, I stumbled onto this post that was trying to list files from a folder, so I tried that just to compare it to my code. It gave me an error telling me it is impossible to list files from that folder. So I tried setting a path to a specific folder, and I got an error saying the path can't be made. This is the code I used for the last part: tell application "Finder" set folderPath to folder "Macintosh HD: Users:Jonathan:Desktop:Send_Mail" set fileList to name of every file in folderPath end tell and this is the error I got. error "Finder got an error: Can’t get folder \"Macintosh HD: Users:Jonathan:Desktop:Send_Mail\"." number -1728 from folder "Macintosh HD: Users:Jonathan:Desktop:Send_Mail". I later tried with another folder, and I always get this error, even when using the Users folder for example. Any Suggestions? thanks

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  • How can I install Satchmo?

    - by Jonathan Hayward
    I am trying to install Satchmo 0.9 on an Ubuntu 9.10 guest off of the instructions at http://bitbucket.org/chris1610/satchmo/downloads/Satchmo.pdf. I run into difficulties at 2.1.2: pip install -r http://bitbucket.org/chris1610/satchmo/raw/tip/scripts/requirements.txt pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo The first command fails because a compile error for how it's trying to build PIL. So I ran an "aptitude install python-imaging", locally copy the first line's requirements.text, and remove the line that's unsuccessfully trying to build PIL. The first line completes without error, as does the second. The next step tells me to change directory to the /path/to/new/store, and run: python clonesatchmo.py A little bit of trouble here; I am told that clonesatchmo.py will be in /bin by now, and it isn't there, but I put some Satchmo stuff under /usr/local, create a symlink in /bin, and run: python /bin/clonesatchmo.py This gives: jonathan@ubuntu:~/store$ python /bin/clonesatchmo.py Creating the Satchmo Application Traceback (most recent call last): File "/bin/clonesatchmo.py", line 108, in <module> create_satchmo_site(opts.site_name) File "/bin/clonesatchmo.py", line 47, in create_satchmo_site import satchmo_skeleton ImportError: No module named satchmo_skeleton A find after apparently checking out the repository reveals that there is no file with a name like satchmo*skeleton* on my system. I thought that bash might be prone to take part of the second pip invocation's URL as the beginning of a comment; I tried both: pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9\#egg=satchmo pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo Neither way of doing it seems to take care of the import error mentioned above. How can I get a Satchmo installation under Ubuntu, or at least enough of a Satchmo installation that I am able to start with a skeleton of a store and then flesh it out the way I want? Thanks, Jonathan

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  • How can I install Satchmo?

    - by Jonathan Hayward
    I am trying to install Satchmo 0.9 on an Ubuntu 9.10 32-bit guest off of the instructions at http://bitbucket.org/chris1610/satchmo/downloads/Satchmo.pdf. I run into difficulties at 2.1.2: pip install -r http://bitbucket.org/chris1610/satchmo/raw/tip/scripts/requirements.txt pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo The first command fails because a compile error for how it's trying to build PIL. So I ran an "aptitude install python-imaging", locally copy the first line's requirements.text, and remove the line that's unsuccessfully trying to build PIL. The first line completes without reported error, as does the second. The next step tells me to change directory to the /path/to/new/store, and run: python clonesatchmo.py A little bit of trouble here; I am told that clonesatchmo.py will be in /bin by now, and it isn't there, but I put some Satchmo stuff under /usr/local, create a symlink in /bin, and run: python /bin/clonesatchmo.py This gives: jonathan@ubuntu:~/store$ python /bin/clonesatchmo.py Creating the Satchmo Application Traceback (most recent call last): File "/bin/clonesatchmo.py", line 108, in <module> create_satchmo_site(opts.site_name) File "/bin/clonesatchmo.py", line 47, in create_satchmo_site import satchmo_skeleton ImportError: No module named satchmo_skeleton A find after apparently checking out the repository reveals that there is no file with a name like satchmo*skeleton* on my system. I thought that bash might be prone to take part of the second pip invocation's URL as the beginning of a comment; I tried both: pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9\#egg=satchmo pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo Neither way of doing it seems to take care of the import error mentioned above. How can I get a Satchmo installation under Ubuntu, or at least enough of a Satchmo installation that I am able to start with a skeleton of a store and then flesh it out the way I want? Thanks, Jonathan

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  • Free eBook "Troubleshooting SQL Server: A Guide for the Accidental DBA"

    - by TATWORTH
    "SQL Server-related performance problems come up regularly and diagnosing and solving them can be difficult and time consuming. Read SQL Server MVP Jonathan Kehayias’ Troubleshooting SQL Server: A Guide for the Accidental DBA for descriptions of the most common issues and practical solutions to fix them quickly and accurately." Please go to http://www.red-gate.com/products/dba/sql-monitor/entrypage/tame-unruly-sql-servers-ebook RedGate produce some superb tools for SQL Server. Jonathan's book is excellent - I commend it to all SQL DBA and developers.

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  • dazzle DVC100 in live movie maker

    - by Jonathan
    How can I use the Pinnacle Dazzle (it is a USB device which lets you plug in a video player or other analogue source) with Windows live movie maker (because it is just simple and I don't need effects/editing etc) Or is there a way I can use it on my Macbook Pro? Jonathan

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  • Is pdf virus proof?

    - by Jonathan
    I am creating a secure document portal for a client. One of the things that they are worried about is having someone upload a document with a virus. One solution that might work is to enforce that they only upload pdf files. My question is two fold: Most importantly, is a pdf document virus proof? How can you determine in a *nix environment that a file is a pdf, besides just looking at the extension. Thanks! Jonathan

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  • Ssh, run a command on login, and then Stay Logged In?

    - by jonathan
    I tried this with expect, but it didn't work: it closed the connection at the end. Can we run a script via ssh which will log into remote machines, run a command, and not disconnect? So ssh in a machine, cd to such and such a directory, and then run a command, and stay logged in. -Jonathan (expect I used) #!/usr/bin/expect -f set password [lrange $argv 0 0] spawn ssh root@marlboro "cd /tmp; ls -altr | tail" expect "?assword:*" send -- "$password\r" send -- "\r" interact

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  • Network is not working anymore - Ubuntu 12.04

    - by Jonathan
    Network is not working anymore - Ubuntu 12.04 Hello, I have a problem with my network connection. I have been using the same laptop with Ubuntu and the same connection for more than a year, and suddenly yesterday the connection stopped working (both wireless and wired). I've tested with another computer and the connection is fine (both wireless and wired). I've been reading similar posts but I haven't found a solution yet. I tried a few commands that I'm posting here (my system is in spanish, so I have traslated it to english, maybe the terms are not accurate): grep -i eth /var/log/syslog | tail Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: (eth0): now managed Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: (eth0): device state change: unmanaged - unavailable (reason 'managed') [10 20 2] Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: (eth0): bringing up device. Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: (eth0): preparing device. Jun 3 18:45:40 vanesa-pc kernel: [ 7351.845743] forcedeth 0000:00:0a.0: irq 41 for MSI/MSI-X Jun 3 18:45:40 vanesa-pc kernel: [ 7351.845984] forcedeth 0000:00:0a.0: eth0: no link during initialization Jun 3 18:45:40 vanesa-pc kernel: [ 7351.847103] ADDRCONF(NETDEV_UP): eth0: link is not ready Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: (eth0): deactivating device (reason 'managed') [2] Jun 3 18:45:40 vanesa-pc NetworkManager[3584]: Added default wired connection 'Wired connection 1' for /sys/devices/pci0000:00/0000:00:0a.0/net/eth0 Jun 3 18:45:40 vanesa-pc kernel: [ 7351.848817] ADDRCONF(NETDEV_UP): eth0: link is not ready ifconfig -a eth0 Link encap:Ethernet addressHW 00:1b:24:fc:a8:d1 ACTIVE BROADCAST MULTICAST MTU:1500 Metric:1 Packages RX:0 errors:16 lost:0 overruns:0 frame:16 Packages TX:123 errors:0 lost:0 overruns:0 carrier:0 colissions:0 length.tailTX:1000 Bytes RX:0 (0.0 B) TX bytes:26335 (26.3 KB) Interruption:41 Base address: 0x2000 lo Link encap:Local loop Inet address:127.0.0.1 Mask:255.0.0.0 Inet6 address: ::1/128 Scope:Host ACTIVE LOOP WORKING MTU:16436 Metrics:1 Packages RX:1550 errors:0 lost:0 overruns:0 frame:0 Packages TX:1550 errors:0 lost:0 overruns:0 carrier:0 colissions:0 long.tailTX:0 Bytes RX:125312 (125.3 KB) TX bytes:125312 (125.3 KB) iwconfig lo no wireless extensions. eth0 no wireless extensions. sudo lshw -C network *-network description: Ethernet interface product: MCP67 Ethernet manufacturer: NVIDIA Corporation Physical id: a bus information: pci@0000:00:0a.0 logical name: eth0 version: a2 series: 00:1b:24:fc:a8:d1 capacity: 100Mbit/s width: 32 bits clock: 66MHz capacities: pm msi ht bus_master cap_list ethernet physical mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=forcedeth driverversion=0.64 latency=0 link=no maxlatency=20 mingnt=1 multicast=yes port=MII resources: irq:41 memoria:f6288000-f6288fff ioport:30f8(size=8) memoria:f6289c00-f6289cff memoria:f6289800-f628980f lsmod Module Size Used by usbhid 41906 0 hid 77367 1 usbhid rfcomm 38139 0 parport_pc 32114 0 ppdev 12849 0 bnep 17830 2 bluetooth 158438 10 rfcomm,bnep binfmt_misc 17292 1 joydev 17393 0 hp_wmi 13652 0 sparse_keymap 13658 1 hp_wmi nouveau 708198 3 ttm 65344 1 nouveau drm_kms_helper 45466 1 nouveau drm 197692 5 nouveau,ttm,drm_kms_helper i2c_algo_bit 13199 1 nouveau psmouse 87213 0 mxm_wmi 12859 1 nouveau serio_raw 13027 0 k8temp 12905 0 i2c_nforce2 12906 0 wmi 18744 2 hp_wmi,mxm_wmi video 19068 1 nouveau mac_hid 13077 0 lp 17455 0 parport 40930 3 parport_pc,ppdev,lp forcedeth 58096 0 Let me know if I can give you more information. Thank you very much in advance, Jonathan

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  • A quick look at: sys.dm_os_buffer_descriptors

    - by Jonathan Allen
    SQL Server places data into cache as it reads it from disk so as to speed up future queries. This dmv lets you see how much data is cached at any given time and knowing how this changes over time can help you ensure your servers run smoothly and are adequately resourced to run your systems. This dmv gives the number of cached pages in the buffer pool along with the database id that they relate to: USE [tempdb] GO SELECT COUNT(*) AS cached_pages_count , CASE database_id WHEN 32767 THEN 'ResourceDb' ELSE DB_NAME(database_id) END AS Database_name FROM sys.dm_os_buffer_descriptors GROUP BY DB_NAME(database_id) , database_id ORDER BY cached_pages_count DESC; This gives you results which are quite useful, but if you add a new column with the code: …to convert the pages value to show a MB value then they become more relevant and meaningful. To see how your server reacts to queries, start up SSMS and connect to a test server and database – mine is called AdventureWorks2008. Make sure you start from a know position by running: -- Only run this on a test server otherwise your production server's-- performance may drop off a cliff and your phone will start ringing. DBCC DROPCLEANBUFFERS GO Now we can run a query that would normally turn a DBA’s hair white: USE [AdventureWorks2008] go SELECT * FROM [Sales].[SalesOrderDetail] AS sod INNER JOIN [Sales].[SalesOrderHeader] AS soh ON [sod].[SalesOrderID] = [soh].[SalesOrderID] …and then check our cache situation: A nice low figure – not! Almost 2000 pages of data in cache equating to approximately 15MB. Luckily these tables are quite narrow; if this had been on a table with more columns then this could be even more dramatic. So, let’s make our query more efficient. After resetting the cache with the DROPCLEANBUFFERS and FREEPROCCACHE code above, we’ll only select the columns we want and implement a WHERE predicate to limit the rows to a specific customer. SELECT [sod].[OrderQty] , [sod].[ProductID] , [soh].[OrderDate] , [soh].[CustomerID] FROM [Sales].[SalesOrderDetail] AS sod INNER JOIN [Sales].[SalesOrderHeader] AS soh ON [sod].[SalesOrderID] = [soh].[SalesOrderID] WHERE [soh].[CustomerID] = 29722 …and check our effect cache: Now that is more sympathetic to our server and the other systems sharing its resources. I can hear you asking: “What has this got to do with logging, Jonathan?” Well, a smart DBA will keep an eye on this metric on their servers so they know how their hardware is coping and be ready to investigate anomalies so that no ‘disruptive’ code starts to unsettle things. Capturing this information over a period of time can lead you to build a picture of how a database relies on the cache and how it interacts with other databases. This might allow you to decide on appropriate schedules for over night jobs or otherwise balance the work of your server. You could schedule this job to run with a SQL Agent job and store the data in your DBA’s database by creating a table with: IF OBJECT_ID('CachedPages') IS NOT NULL DROP TABLE CachedPages CREATE TABLE CachedPages ( cached_pages_count INT , MB INT , Database_Name VARCHAR(256) , CollectedOn DATETIME DEFAULT GETDATE() ) …and then filling it with: INSERT INTO [dbo].[CachedPages] ( [cached_pages_count] , [MB] , [Database_Name] ) SELECT COUNT(*) AS cached_pages_count , ( COUNT(*) * 8.0 ) / 1024 AS MB , CASE database_id WHEN 32767 THEN 'ResourceDb' ELSE DB_NAME(database_id) END AS Database_name FROM sys.dm_os_buffer_descriptors GROUP BY database_id After this has been left logging your system metrics for a while you can easily see how your databases use the cache over time and may see some spikes that warrant your attention. This sort of logging can be applied to all sorts of server statistics so that you can gather information that will give you baseline data on how your servers are performing. This means that when you get a problem you can see what statistics are out of their normal range and target you efforts to resolve the issue more rapidly.

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  • How to Automate your Database Documentation

    - by Jonathan Hickford
    In my previous post, “Automating Deployments with SQL Compare command line” I looked at how teams can automate the deployment and post deployment validation of SQL Server databases using the command line versions of Red Gate tools. In this post I’m looking at another use for the command line tools, namely using them to generate up-to-date documentation with every database change. There are many reasons why up-to-date documentation is valuable. For example when somebody new has to work on or administer a database for the first time, or when a new database comes into service. Having database documentation reduces the risks of making incorrect decisions when making changes. Documentation is very useful to business intelligence analysts when writing reports, for example in SSRS. There are a couple of great examples talking about why up to date documentation is valuable on this site:  Database Documentation – Lands of Trolls: Why and How? and Database Documentation Using SQL Doc. The short answer is that it can save you time and reduce risk when you need that most! SQL Doc is a fast simple tool that automatically generates database documentation. It can create documents in HTML, Word or pdf files. The documentation contains information about object definitions and dependencies, along with any other information you want to associate with each object. The SQL Doc GUI, which is included in Red Gate’s SQL Developer Bundle and SQL Toolbelt, allows you to add additional notes to objects, and customise which objects are shown in the docs.  These settings can be saved as a .sqldoc project file. The SQL Doc command line can use this project file to automatically update the documentation every time the database is changed, ensuring that documentation that is always up to date. The simplest way to keep documentation up to date is probably to use a scheduled task to run a script every day. However if you have a source controlled database, or are using a Continuous Integration (CI) server or a build server, it may make more sense to use that instead. If  you’re using SQL Source Control or SSDT Database Projects to help version control your database, you can automatically update the documentation after each change is made to the source control repository that contains your database. To get this automation in place,  you can use the functionality of a Continuous Integration (CI) server, which can trigger commands to run when a source control repository has changed. A CI server will also capture and save the documentation that is created as an artifact, so you can always find the exact documentation for a specific version of the database. This forms an always up to date data dictionary. If you don’t already have a CI server in place there are several you can use, such as the free open source Jenkins or the free starter editions of TeamCity. I won’t cover setting these up in this article, but there is information about using CI servers for automating database tasks on the Red Gate Database Delivery webpage. You may be interested in Red Gate’s SQL CI utility (part of the SQL Automation Pack) which is an easy way to update a database with the latest changes from source control. The PowerShell example below shows how to create the documentation from a database. That database might be your integration database or a shared development database that is always up to date with the latest changes. $serverName = "server\instance" $databaseName = "databaseName" # If you want to document multiple databases use a comma separated list $userName = "username" $password = "password" # Path to SQLDoc.exe $SQLDocPath = "C:\Program Files (x86)\Red Gate\SQL Doc 3\SQLDoc.exe" $arguments = @( "/server:$($serverName)", "/database:$($databaseName)", "/username:$($userName)", "/password:$($password)", "/filetype:html", "/outputfolder:.", # "/project:$args[0]", # If you already have a .sqldoc project file you can pass it as an argument to this script. Values in the project will be overridden with any options set on the command line "/name:$databaseName Report", "/copyrightauthor:$([Environment]::UserName)" ) write-host $arguments & $SQLDocPath $arguments There are several options you can set on the command line to vary how your documentation is created. For example, you can document multiple databases or exclude certain types of objects. In the example above, we set the name of the report to match the database name, and use the current Windows user as the documentation author. For more examples of how you can customise the report from the command line please see the SQL Doc command line documentation If you already have a .sqldoc project file, or wish to further customise the report by including or excluding specific objects, you can use this project on the command line. Any settings you specify on the command line will override the defaults in the project. For details of what you can customise in the project please see the SQL Doc project documentation. In the example above, the line to use a project is commented out, but you can uncomment this line and then pass a path to a .sqldoc project file as an argument to this script.  Conclusion Keeping documentation about your databases up to date is very easy to set up using SQL Doc and PowerShell. By using a CI server to run this process you can trigger the documentation to be run on every change to a source controlled database, and keep historic documentation available. If you are considering more advanced database automation, e.g. database unit testing, change script generation, deploying to large numbers of targets and backup/verification, please email me at Jonathan[email protected] for further script samples or if you have any questions.

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  • Upgrading openSUSE 11.1 with Plesk Panel 9.3 to PHP 5.3

    - by Jonathan
    I'm running a VPS with openSUSE 11.1 (i586). On the VPS is Parallels Plesk Panel 9.3.0 installed. The current PHP-version is PHP 5.2.11. I want to upgrade PHP to PHP 5.3, but I can't find good instructions on how to do this. If I check for updates in Zypper, it says this is the latest release. In the Plesk Updates isn't an update either, both via the webbased interface and the command line interface. On Software.openSUSE.org I can find packages for PHP 5.3.1 in both the server:php/server_apache_openSUSE_11.1-repo and the server:php/openSUSE_11.1-repo (can't post the link because I'm a newbie here). But if I add one of those to Zypper, I still don't see an update. Is there here somebody who knows how to do this? And is it completely safe to update that way? I don't want to end up with a broken VPS... Thanks! Jonathan

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  • When your field-terminating char appears within field values

    - by Jonathan Sampson
    I've had a very colorful morning learning the innerparts of Linux's sort command, and have come across yet another issue that I can't seem to find an answer for in the documentation. I'm currently using -t, to indicate that my fields are split by the comma character, but I'm finding that in some of my files, the comma is used (between double-quotes) within values: Jonathan Sampson,,[email protected],0987654321 "Foobar CEO,","CEO,",[email protected],, How can I use a comma to terminate my fields, but ignore the occurences of it within values? Is this fairly simple, or do I need to re-export all of my data using a more-foreign field-terminator?

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  • Is it possible to have an external server with in a companies firewall?

    - by Jonathan
    Hi guys, I am sure this is server admin 101,but I am unsure of the answer and would love some help. I am a software developer I have built an application for a client and am currently hosting it successfully on SliceHost. We are now coming out of Beta and the client wants to have the application within their Firewall, but they do not want to deal with headache of hosting and maintaining the server. Is there a way I can recommend that we put our server at SliceHost within their Firewall? Is that an easy thing to do? If that is not possible, what should I recommend to my client? Thanks! Jonathan

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  • Automating deployments with the SQL Compare command line

    - by Jonathan Hickford
    In my previous article, “Five Tips to Get Your Organisation Releasing Software Frequently” I looked at how teams can automate processes to speed up release frequency. In this post, I’m looking specifically at automating deployments using the SQL Compare command line. SQL Compare compares SQL Server schemas and deploys the differences. It works very effectively in scenarios where only one deployment target is required – source and target databases are specified, compared, and a change script is automatically generated and applied. But if multiple targets exist, and pressure to increase the frequency of releases builds, this solution quickly becomes unwieldy.   This is where SQL Compare’s command line comes into its own. I’ve put together a PowerShell script that loops through the Servers table and pulls out the server and database, these are then passed to sqlcompare.exe to be used as target parameters. In the example the source database is a scripts folder, a folder structure of scripted-out database objects used by both SQL Source Control and SQL Compare. The script can easily be adapted to use schema snapshots.     -- Create a DeploymentTargets database and a Servers table CREATE DATABASE DeploymentTargets GO USE DeploymentTargets GO CREATE TABLE [dbo].[Servers]( [id] [int] IDENTITY(1,1) NOT NULL, [serverName] [nvarchar](50) NULL, [environment] [nvarchar](50) NULL, [databaseName] [nvarchar](50) NULL, CONSTRAINT [PK_Servers] PRIMARY KEY CLUSTERED ([id] ASC) ) GO -- Now insert your target server and database details INSERT INTO dbo.Servers ( serverName , environment , databaseName) VALUES ( N'myserverinstance' , N'myenvironment1' , N'mydb1') INSERT INTO dbo.Servers ( serverName , environment , databaseName) VALUES ( N'myserverinstance' , N'myenvironment2' , N'mydb2') Here’s the PowerShell script you can adapt for yourself as well. # We're holding the server names and database names that we want to deploy to in a database table. # We need to connect to that server to read these details $serverName = "" $databaseName = "DeploymentTargets" $authentication = "Integrated Security=SSPI" #$authentication = "User Id=xxx;PWD=xxx" # If you are using database authentication instead of Windows authentication. # Path to the scripts folder we want to deploy to the databases $scriptsPath = "SimpleTalk" # Path to SQLCompare.exe $SQLComparePath = "C:\Program Files (x86)\Red Gate\SQL Compare 10\sqlcompare.exe" # Create SQL connection string, and connection $ServerConnectionString = "Data Source=$serverName;Initial Catalog=$databaseName;$authentication" $ServerConnection = new-object system.data.SqlClient.SqlConnection($ServerConnectionString); # Create a Dataset to hold the DataTable $dataSet = new-object "System.Data.DataSet" "ServerList" # Create a query $query = "SET NOCOUNT ON;" $query += "SELECT serverName, environment, databaseName " $query += "FROM dbo.Servers; " # Create a DataAdapter to populate the DataSet with the results $dataAdapter = new-object "System.Data.SqlClient.SqlDataAdapter" ($query, $ServerConnection) $dataAdapter.Fill($dataSet) | Out-Null # Close the connection $ServerConnection.Close() # Populate the DataTable $dataTable = new-object "System.Data.DataTable" "Servers" $dataTable = $dataSet.Tables[0] #For every row in the DataTable $dataTable | FOREACH-OBJECT { "Server Name: $($_.serverName)" "Database Name: $($_.databaseName)" "Environment: $($_.environment)" # Compare the scripts folder to the database and synchronize the database to match # NB. Have set SQL Compare to abort on medium level warnings. $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/AbortOnWarnings:Medium") # + @("/sync" ) # Commented out the 'sync' parameter for safety, write-host $arguments & $SQLComparePath $arguments "Exit Code: $LASTEXITCODE" # Some interesting variations # Check that every database matches a folder. # For example this might be a pre-deployment step to validate everything is at the same baseline state. # Or a post deployment script to validate the deployment worked. # An exit code of 0 means the databases are identical. # # $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/Assertidentical") # Generate a report of the difference between the folder and each database. Generate a SQL update script for each database. # For example use this after the above to generate upgrade scripts for each database # Examine the warnings and the HTML diff report to understand how the script will change objects # #$arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/ScriptFile:update_$($_.environment+"_"+$_.databaseName).sql", "/report:update_$($_.environment+"_"+$_.databaseName).html" , "/reportType:Interactive", "/showWarnings", "/include:Identical") } It’s worth noting that the above example generates the deployment scripts dynamically. This approach should be problem-free for the vast majority of changes, but it is still good practice to review and test a pre-generated deployment script prior to deployment. An alternative approach would be to pre-generate a single deployment script using SQL Compare, and run this en masse to multiple targets programmatically using sqlcmd, or using a tool like SQL Multi Script.  You can use the /ScriptFile, /report, and /showWarnings flags to generate change scripts, difference reports and any warnings.  See the commented out example in the PowerShell: #$arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/ScriptFile:update_$($_.environment+"_"+$_.databaseName).sql", "/report:update_$($_.environment+"_"+$_.databaseName).html" , "/reportType:Interactive", "/showWarnings", "/include:Identical") There is a drawback of running a pre-generated deployment script; it assumes that a given database target hasn’t drifted from its expected state. Often there are (rightly or wrongly) many individuals within an organization who have permissions to alter the production database, and changes can therefore be made outside of the prescribed development processes. The consequence is that at deployment time, the applied script has been validated against a target that no longer represents reality. The solution here would be to add a check for drift prior to running the deployment script. This is achieved by using sqlcompare.exe to compare the target against the expected schema snapshot using the /Assertidentical flag. Should this return any differences (sqlcompare.exe Exit Code 79), a drift report is outputted instead of executing the deployment script.  See the commented out example. # $arguments = @("/scripts1:$($scriptsPath)", "/server2:$($_.serverName)", "/database2:$($_.databaseName)", "/Assertidentical") Any checks and processes that should be undertaken prior to a manual deployment, should also be happen during an automated deployment. You might think about triggering backups prior to deployment – even better, automate the verification of the backup too.   You can use SQL Compare’s command line interface along with PowerShell to automate multiple actions and checks that you need in your deployment process. Automation is a practical solution where multiple targets and a higher release cadence come into play. As we know, with great power comes great responsibility – responsibility to ensure that the necessary checks are made so deployments remain trouble-free.  (The code sample supplied in this post automates the simple dynamic deployment case – if you are considering more advanced automation, e.g. the drift checks, script generation, deploying to large numbers of targets and backup/verification, please email me at Jonathan[email protected] for further script samples or if you have further questions)

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  • How to read Hebrew text using System.IO.FileStream?

    - by Jonathan Dyle
    Hi all Am I missing something or does System.IO.FileStream not read Unicode text files containing Hebrew? public TextReader CSVReader(Stream s, Encoding enc) { this.stream = s; if (!s.CanRead) { throw new CSVReaderException("Could not read the given CSV stream!"); } reader = (enc != null) ? new StreamReader(s, enc) : new StreamReader(s); } Thanks Jonathan

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  • Sample app for Rails 3?

    - by Jonathan
    Can someone point me to a solid sample app that shows how to use the new features and syntax of Rails 3? Its been answered before for earlier versions (http://stackoverflow.com/questions/248371/whats-the-best-open-source-ruby-on-rails-project-to-learn-from), but I have not seen one for Rails 3. Thanks! Jonathan

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  • Trigger Div Click From Link

    - by Jonathan Lyon
    Hi all I have a site http://www.thebalancedbody.ca/ and there is a pop out contact form on the left (Contact) which has this id <div id="mycontactform">. There is also a link in the footer called CONTACT US <a href="#" title="CONTACT US">CONTACT US</a> and I need this link to trigger the pop out contact form as if the contact tab was clicked manually. Is this possible and how would I do it? Thanks JOnathan

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  • Index page in Magento is way too slow, what can I do?

    - by Jonathan
    Weirdly, the index page of my magento commerce is very slow, while when you navigate the products, brands, searchs etc is very fast, but everytime you click on the banner to go for home or enter the website, it take ages to load I wonder what can I do about this? I don't know where to start, since I am new at magento. I thought I could go on and read the code, but that would take ages too, since magento is very big. Maybe I can analyze it somehow? Thanks, Jonathan

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