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• Query Tuning Mastery at PASS Summit 2012: The Demos

  - by Adam Machanic

  For the second year in a row, I was asked to deliver a 500-level "Query Tuning Mastery" talk in room 6E of the Washington State Convention Center, for the PASS Summit. ( Here's some information about last year's talk, on workspace memory. ) And for the second year in a row, I had to deliver said talk at 10:15 in the morning, in a room used as overflow for the keynote, following a keynote speaker that didn't stop speaking on time. Frustrating! Last Thursday, after very, very quickly setting up and...(read more)

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• The Red Gate and .NET Reflector Debacle

  - by Rick Strahl

  About a month ago Red Gate – the company who owns the NET Reflector tool most .NET devs use at one point or another – decided to change their business model for Reflector and take the product from free to a fully paid for license model. As a bit of history: .NET Reflector was originally created by Lutz Roeder as a free community tool to inspect .NET assemblies. Using Reflector you can examine the types in an assembly, drill into type signatures and quickly disassemble code to see how a particular method works.  In case you’ve been living under a rock and you’ve never looked at Reflector, here’s what it looks like drilled into an assembly from disk with some disassembled source code showing: Note that you get tons of information about each element in the tree, and almost all related types and members are clickable both in the list and source view so it’s extremely easy to navigate and follow the code flow even in this static assembly only view. For many year’s Lutz kept the the tool up to date and added more features gradually improving an already amazing tool and making it better. Then about two and a half years ago Red Gate bought the tool from Lutz. A lot of ruckus and noise ensued in the community back then about what would happen with the tool and… for the most part very little did. Other than the incessant update notices with prominent Red Gate promo on them life with Reflector went on. The product didn’t die and and it didn’t go commercial or to a charge model. When .NET 4.0 came out it still continued to work mostly because the .NET feature set doesn’t drastically change how types behave.  Then a month back Red Gate started making noise about a new Version Version 7 which would be commercial. No more free version - and a shit storm broke out in the community. Now normally I’m not one to be critical of companies trying to make money from a product, much less for a product that’s as incredibly useful as Reflector. There isn’t day in .NET development that goes by for me where I don’t fire up Reflector. Whether it’s for examining the innards of the .NET Framework, checking out third party code, or verifying some of my own code and resources. Even more so recently I’ve been doing a lot of Interop work with a non-.NET application that needs to access .NET components and Reflector has been immensely valuable to me (and my clients) if figuring out exact type signatures required to calling .NET components in assemblies. In short Reflector is an invaluable tool to me. Ok, so what’s the problem? Why all the fuss? Certainly the $39 Red Gate is trying to charge isn’t going to kill any developer. If there’s any tool in .NET that’s worth $39 it’s Reflector, right? Right, but that’s not the problem here. The problem is how Red Gate went about moving the product to commercial which borders on the downright bizarre. It’s almost as if somebody in management wrote a slogan: “How can we piss off the .NET community in the most painful way we can?” And that it seems Red Gate has a utterly succeeded. People are rabid, and for once I think that this outrage isn’t exactly misplaced. Take a look at the message thread that Red Gate dedicated from a link off the download page. Not only is Version 7 going to be a paid commercial tool, but the older versions of Reflector won’t be available any longer. Not only that but older versions that are already in use also will continually try to update themselves to the new paid version – which when installed will then expire unless registered properly. There have also been reports of Version 6 installs shutting themselves down and failing to work if the update is refused (I haven’t seen that myself so not sure if that’s true). In other words Red Gate is trying to make damn sure they’re getting your money if you attempt to use Reflector. There’s a lot of temptation there. Think about the millions of .NET developers out there and all of them possibly upgrading – that’s a nice chunk of change that Red Gate’s sitting on. Even with all the community backlash these guys are probably making some bank right now just because people need to get life to move on. Red Gate also put up a Feedback link on the download page – which not surprisingly is chock full with hate mail condemning the move. Oddly there’s not a single response to any of those messages by the Red Gate folks except when it concerns license questions for the full version. It puzzles me what that link serves for other yet than another complete example of failure to understand how to handle customer relations. There’s no doubt that that all of this has caused some serious outrage in the community. The sad part though is that this could have been handled so much less arrogantly and without pissing off the entire community and causing so much ill-will. People are pissed off and I have no doubt that this negative publicity will show up in the sales numbers for their other products. I certainly hope so. Stupidity ought to be painful! Why do Companies do boneheaded stuff like this? Red Gate’s original decision to buy Reflector was hotly debated but at that the time most of what would happen was mostly speculation. But I thought it was a smart move for any company that is in need of spreading its marketing message and corporate image as a vendor in the .NET space. Where else do you get to flash your corporate logo to hordes of .NET developers on a regular basis?  Exploiting that marketing with some goodwill of providing a free tool breeds positive feedback that hopefully has a good effect on the company’s visibility and the products it sells. Instead Red Gate seems to have taken exactly the opposite tack of corporate bullying to try to make a quick buck – and in the process ruined any community goodwill that might have come from providing a service community for free while still getting valuable marketing. What’s so puzzling about this boneheaded escapade is that the company doesn’t need to resort to underhanded tactics like what they are trying with Reflector 7. The tools the company makes are very good. I personally use SQL Compare, Sql Data Compare and ANTS Profiler on a regular basis and all of these tools are essential in my toolbox. They certainly work much better than the tools that are in the box with Visual Studio. Chances are that if Reflector 7 added useful features I would have been more than happy to shell out my $39 to upgrade when the time is right. It’s Expensive to give away stuff for Free At the same time, this episode shows some of the big problems that come with ‘free’ tools. A lot of organizations are realizing that giving stuff away for free is actually quite expensive and the pay back is often very intangible if any at all. Those that rely on donations or other voluntary compensation find that they amount contributed is absolutely miniscule as to not matter at all. Yet at the same time I bet most of those clamouring the loudest on that Red Gate Reflector feedback page that Reflector won’t be free anymore probably have NEVER made a donation to any open source project or free tool ever. The expectation of Free these days is just too great – which is a shame I think. There’s a lot to be said for paid software and having somebody to hold to responsible to because you gave them some money. There’s an incentive –> payback –> responsibility model that seems to be missing from free software (not all of it, but a lot of it). While there certainly are plenty of bad apples in paid software as well, money tends to be a good motivator for people to continue working and improving products. Reasons for giving away stuff are many but often it’s a naïve desire to share things when things are simple. At first it might be no problem to volunteer time and effort but as products mature the fun goes out of it, and as the reality of product maintenance kicks in developers want to get something back for the time and effort they’re putting in doing non-glamorous work. It’s then when products die or languish and this is painful for all to watch. For Red Gate however, I think there was always a pretty good payback from the Reflector acquisition in terms of marketing: Visibility and possible positioning of their products although they seemed to have mostly ignored that option. On the other hand they started this off pretty badly even 2 and a half years back when they aquired Reflector from Lutz with the same arrogant attitude that is evident in the latest episode. You really gotta wonder what folks are thinking in management – the sad part is from advance emails that were circulating, they were fully aware of the shit storm they were inciting with this and I suspect they are banking on the sheer numbers of .NET developers to still make them a tidy chunk of change from upgrades… Alternatives are coming For me personally the single license isn’t a problem, but I actually have a tool that I sell (an interop Web Service proxy generation tool) to customers and one of the things I recommend to use with has been Reflector to view assembly information and to find which Interop classes to instantiate from the non-.NET environment. It’s been nice to use Reflector for this with its small footprint and zero-configuration installation. But now with V7 becoming a paid tool that option is not going to be available anymore. Luckily it looks like the .NET community is jumping to it and trying to fill the void. Amidst the Red Gate outrage a new library called ILSpy has sprung up and providing at least some of the core functionality of Reflector with an open source library. It looks promising going forward and I suspect there will be a lot more support and interest to support this project now that Reflector has gone over to the ‘dark side’…© Rick Strahl, West Wind Technologies, 2005-2011

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• NEW CERTIFICATION: Oracle Certified Expert, Oracle Database 11g Release 2 SQL Tuning

  - by Brandye Barrington

  Oracle Certification announces the release of the new Oracle Certified Expert, Oracle Database 11g Release 2 SQL Tuning certification. This certification is designed forDevelopers, Database Administrators and SQL developers who are proficient at tuning efficient SQL statements. This certification covers topics on core elements such as: identifying and tuning inefficient SQL statements, using automatic SQL tuning, managing optimizer statistics on database objects, implementing partitioning and analyizing queries. Beta testing for the Oracle Database 11g Release 2: SQL Tuning exam (1Z1-117) is now underway and thus is available at the greatly discounted rate of $50 USD. Visit pearsonvue.com/oracle and register for exam 1Z1-117. You can get all preparation details on the Oracle Certification website, including exam objectives, number of questions, time allotments, and pricing. QUICK LINKS: Certification Track: Oracle Certified Expert, Oracle Database 11g Release 2 SQL Tuning Certification Exam: Oracle Database 11g Release 2: SQL Tuning (1Z0-117) Certification Website: About Beta Exams Register Now: Pearson VUE

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• How do I calculate the amount of tuning needed for my server ?

  - by Low Kian Seong

  I have a server which is running a few discrete Python, Java application which most of the time imports data into a PostGreSQL database. I would like to know from people out there who have experience tuning enterprise grade servers how do i go about calculating in a holistic way the amount of tuning needed for my server for example vm.swappiness, vm.overcommit_ratio and other numerical tunings needed for my server. I tried to enable sar on my server to capture daily numbers but these are more along the lines of total numbers and I can't figure out how to allocate memory for my applications. Help would be appreciated. Thanks.

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• Tuning Default WorkManager - Advantages and Disadvantages

  - by Murali Veligeti

  Before discussing on Tuning Default WorkManager, lets have a brief introduction on What is Default WorkManger Before Weblogic Server 9.0 release, we had the concept of Execute Queues. WebLogic Server (before WLS 9.0), processing was performed in multiple execute queues. Different classes of work were executed in different queues, based on priority and ordering requirements, and to avoid deadlocks. In addition to the default execute queue, weblogic.kernel.default, there were pre-configured queues dedicated to internal administrative traffic, such as weblogic.admin.HTTP and weblogic.admin.RMI.Users could control thread usage by altering the number of threads in the default queue, or configure custom execute queues to ensure that particular applications had access to a fixed number of execute threads, regardless of overall system load. From WLS 9.0 release onwards WebLogic Server uses is a single thread pool (single thread pool which is called Default WorkManager), in which all types of work are executed. WebLogic Server prioritizes work based on rules you define, and run-time metrics, including the actual time it takes to execute a request and the rate at which requests are entering and leaving the pool.The common thread pool changes its size automatically to maximize throughput. The queue monitors throughput over time and based on history, determines whether to adjust the thread count. For example, if historical throughput statistics indicate that a higher thread count increased throughput, WebLogic increases the thread count. Similarly, if statistics indicate that fewer threads did not reduce throughput, WebLogic decreases the thread count. This new strategy makes it easier for administrators to allocate processing resources and manage performance, avoiding the effort and complexity involved in configuring, monitoring, and tuning custom executes queues. The Default WorkManager is used to handle thread management and perform self-tuning.This Work Manager is used by an application when no other Work Managers are specified in the application’s deployment descriptors. In many situations, the default Work Manager may be sufficient for most application requirements. WebLogic Server’s thread-handling algorithms assign each application its own fair share by default. Applications are given equal priority for threads and are prevented from monopolizing them. The default work-manager, as its name tells, is the work-manager defined by default.Thus, all applications deployed on WLS will use it. But sometimes, when your application is already in production, it's obvious you can't take your EAR / WAR, update the deployment descriptor(s) and redeploy it.The default work-manager belongs to a thread-pool, as initial thread-pool comes with only five threads, that's not much. If your application has to face a large number of hits, you may want to start with more than that.Well, that's quite easy. You have  two option to do so.1) Modify the config.xmlJust add the following line(s) in your server definition : <server> <name>AdminServer</name> <self-tuning-thread-pool-size-min>100</self-tuning-thread-pool-size-min> <self-tuning-thread-pool-size-max>200</self-tuning-thread-pool-size-max> [...] </server> 2) Adding some JVM parameters Add the following system property in setDomainEnv.sh/setDomainEnv.cmd or startWebLogic.sh/startWebLogic.cmd : -Dweblogic.threadpool.MinPoolSize=100 -Dweblogic.threadpool.MaxPoolSize=100 Reboot WLS and see the option has been taken into account . Disadvantage: So far its fine. But here there is an disadvantage in tuning Default WorkManager. Internally Weblogic Server has many work managers configured for different types of work.  if we run out of threads in the self-tuning pool(because of system property -Dweblogic.threadpool.MaxPoolSize) due to being undersized, then important work that WLS might need to do could be starved.  So, while limiting the self-tuning would limit the default WorkManager and internally it also limits all other internal WorkManagers which WLS uses.So the best alternative is to override the default WorkManager that means creating a WorkManager for the Application and assign the WorkManager for the application instead of tuning the Default WorkManager.

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• FreeBSD performance tuning. Sysctls, loader.conf, kernel

  - by SaveTheRbtz

  I wanted to share knowledge of tuning FreeBSD via sysctl.conf/loader.conf/KENCONF. It was initially based on Igor Sysoev's (author of nginx) presentation about FreeBSD tuning up to 100,000-200,000 active connections. Tunings are for FreeBSD-CURRENT. Since 7.2 amd64 some of them are tuned well by default. Prior 7.0 some of them are boot only (set via /boot/loader.conf) or does not exist at all. sysctl.conf: # No zero mapping feature # May break wine # (There are also reports about broken samba3) #security.bsd.map_at_zero=0 # If you have really busy webserver with apache13 you may run out of processes #kern.maxproc=10000 # Same for servers with apache2 / Pound #kern.threads.max_threads_per_proc=4096 # Max. backlog size kern.ipc.somaxconn=4096 # Shared memory // 7.2+ can use shared memory > 2Gb kern.ipc.shmmax=2147483648 # Sockets kern.ipc.maxsockets=204800 # Can cause this on older kernels: # http://old.nabble.com/Significant-performance-regression-for-increased-maxsockbuf-on-8.0-RELEASE-tt26745981.html#a26745981 ) kern.ipc.maxsockbuf=10485760 # Mbuf 2k clusters (on amd64 7.2+ 25600 is default) # For such high value vm.kmem_size must be increased to 3G kern.ipc.nmbclusters=262144 # Jumbo pagesize(_SC_PAGESIZE) clusters # Used as general packet storage for jumbo frames # can be monitored via `netstat -m` #kern.ipc.nmbjumbop=262144 # Jumbo 9k/16k clusters # If you are using them #kern.ipc.nmbjumbo9=65536 #kern.ipc.nmbjumbo16=32768 # For lower latency you can decrease scheduler's maximum time slice # default: stathz/10 (~ 13) #kern.sched.slice=1 # Increase max command-line length showed in `ps` (e.g for Tomcat/Java) # Default is PAGE_SIZE / 16 or 256 on x86 # This avoids commands to be presented as [executable] in `ps` # For more info see: http://www.freebsd.org/cgi/query-pr.cgi?pr=120749 kern.ps_arg_cache_limit=4096 # Every socket is a file, so increase them kern.maxfiles=204800 kern.maxfilesperproc=200000 kern.maxvnodes=200000 # On some systems HPET is almost 2 times faster than default ACPI-fast # Useful on systems with lots of clock_gettime / gettimeofday calls # See http://old.nabble.com/ACPI-fast-default-timecounter,-but-HPET-83--faster-td23248172.html # After revision 222222 HPET became default: http://svnweb.freebsd.org/base?view=revision&revision=222222 kern.timecounter.hardware=HPET # Small receive space, only usable on http-server, on file server this # should be increased to 65535 or even more #net.inet.tcp.recvspace=8192 # This is useful on Fat-Long-Pipes #net.inet.tcp.recvbuf_max=10485760 #net.inet.tcp.recvbuf_inc=65535 # Small send space is useful for http servers that serve small files # Autotuned since 7.x net.inet.tcp.sendspace=16384 # This is useful on Fat-Long-Pipes #net.inet.tcp.sendbuf_max=10485760 #net.inet.tcp.sendbuf_inc=65535 # Turn off receive autotuning # You can play with it. #net.inet.tcp.recvbuf_auto=0 #net.inet.tcp.sendbuf_auto=0 # This should be enabled if you going to use big spaces (>64k) # Also timestamp field is useful when using syncookies net.inet.tcp.rfc1323=1 # Turn this off on high-speed, lossless connections (LAN 1Gbit+) # If you set it there is no need in TCP_NODELAY sockopt (see man tcp) net.inet.tcp.delayed_ack=0 # This feature is useful if you are serving data over modems, Gigabit Ethernet, # or even high speed WAN links (or any other link with a high bandwidth delay product), # especially if you are also using window scaling or have configured a large send window. # Automatically disables on small RTT ( http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/tcp_subr.c?#rev1.237 ) # This sysctl was removed in 10-CURRENT: # See: http://www.mail-archive.com/[email protected]/msg06178.html #net.inet.tcp.inflight.enable=0 # TCP slowstart algorithm tunings # We assuming we have very fast clients #net.inet.tcp.slowstart_flightsize=100 #net.inet.tcp.local_slowstart_flightsize=100 # Disable randomizing of ports to avoid false RST # Before usage check SA here www.bsdcan.org/2006/papers/ImprovingTCPIP.pdf # (it's also says that port randomization auto-disables at some conn.rates, but I didn't checked it thou) #net.inet.ip.portrange.randomized=0 # Increase portrange # For outgoing connections only. Good for seed-boxes and ftp servers. net.inet.ip.portrange.first=1024 net.inet.ip.portrange.last=65535 # # stops route cache degregation during a high-bandwidth flood # http://www.freebsd.org/doc/en/books/handbook/securing-freebsd.html #net.inet.ip.rtexpire=2 net.inet.ip.rtminexpire=2 net.inet.ip.rtmaxcache=1024 # Security net.inet.ip.redirect=0 net.inet.ip.sourceroute=0 net.inet.ip.accept_sourceroute=0 net.inet.icmp.maskrepl=0 net.inet.icmp.log_redirect=0 net.inet.icmp.drop_redirect=1 net.inet.tcp.drop_synfin=1 # # There is also good example of sysctl.conf with comments: # http://www.thern.org/projects/sysctl.conf # # icmp may NOT rst, helpful for those pesky spoofed # icmp/udp floods that end up taking up your outgoing # bandwidth/ifqueue due to all that outgoing RST traffic. # #net.inet.tcp.icmp_may_rst=0 # Security net.inet.udp.blackhole=1 net.inet.tcp.blackhole=2 # IPv6 Security # For more info see http://www.fosslc.org/drupal/content/security-implications-ipv6 # Disable Node info replies # To see this vulnerability in action run `ping6 -a sglAac ::1` or `ping6 -w ::1` on unprotected node net.inet6.icmp6.nodeinfo=0 # Turn on IPv6 privacy extensions # For more info see proposal http://unix.derkeiler.com/Mailing-Lists/FreeBSD/net/2008-06/msg00103.html net.inet6.ip6.use_tempaddr=1 net.inet6.ip6.prefer_tempaddr=1 # Disable ICMP redirect net.inet6.icmp6.rediraccept=0 # Disable acceptation of RA and auto linklocal generation if you don't use them #net.inet6.ip6.accept_rtadv=0 #net.inet6.ip6.auto_linklocal=0 # Increases default TTL, sometimes useful # Default is 64 net.inet.ip.ttl=128 # Lessen max segment life to conserve resources # ACK waiting time in miliseconds # (default: 30000. RFC from 1979 recommends 120000) net.inet.tcp.msl=5000 # Max bumber of timewait sockets net.inet.tcp.maxtcptw=200000 # Don't use tw on local connections # As of 15 Apr 2009. Igor Sysoev says that nolocaltimewait has some buggy realization. # So disable it or now till get fixed #net.inet.tcp.nolocaltimewait=1 # FIN_WAIT_2 state fast recycle net.inet.tcp.fast_finwait2_recycle=1 # Time before tcp keepalive probe is sent # default is 2 hours (7200000) #net.inet.tcp.keepidle=60000 # Should be increased until net.inet.ip.intr_queue_drops is zero net.inet.ip.intr_queue_maxlen=4096 # Interrupt handling via multiple CPU, but with context switch. # You can play with it. Default is 1; #net.isr.direct=0 # This is for routers only #net.inet.ip.forwarding=1 #net.inet.ip.fastforwarding=1 # This speed ups dummynet when channel isn't saturated net.inet.ip.dummynet.io_fast=1 # Increase dummynet(4) hash #net.inet.ip.dummynet.hash_size=2048 #net.inet.ip.dummynet.max_chain_len # Should be increased when you have A LOT of files on server # (Increase until vfs.ufs.dirhash_mem becomes lower) vfs.ufs.dirhash_maxmem=67108864 # Note from commit http://svn.freebsd.org/base/head@211031 : # For systems with RAID volumes and/or virtualization envirnments, where # read performance is very important, increasing this sysctl tunable to 32 # or even more will demonstratively yield additional performance benefits. vfs.read_max=32 # Explicit Congestion Notification (see http://en.wikipedia.org/wiki/Explicit_Congestion_Notification) net.inet.tcp.ecn.enable=1 # Flowtable - flow caching mechanism # Useful for routers #net.inet.flowtable.enable=1 #net.inet.flowtable.nmbflows=65535 # Extreme polling tuning #kern.polling.burst_max=1000 #kern.polling.each_burst=1000 #kern.polling.reg_frac=100 #kern.polling.user_frac=1 #kern.polling.idle_poll=0 # IPFW dynamic rules and timeouts tuning # Increase dyn_buckets till net.inet.ip.fw.curr_dyn_buckets is lower net.inet.ip.fw.dyn_buckets=65536 net.inet.ip.fw.dyn_max=65536 net.inet.ip.fw.dyn_ack_lifetime=120 net.inet.ip.fw.dyn_syn_lifetime=10 net.inet.ip.fw.dyn_fin_lifetime=2 net.inet.ip.fw.dyn_short_lifetime=10 # Make packets pass firewall only once when using dummynet # i.e. packets going thru pipe are passing out from firewall with accept #net.inet.ip.fw.one_pass=1 # shm_use_phys Wires all shared pages, making them unswappable # Use this to lessen Virtual Memory Manager's work when using Shared Mem. # Useful for databases #kern.ipc.shm_use_phys=1 # ZFS # Enable prefetch. Useful for sequential load type i.e fileserver. # FreeBSD sets vfs.zfs.prefetch_disable to 1 on any i386 systems and # on any amd64 systems with less than 4GB of avaiable memory # For additional info check this nabble thread http://old.nabble.com/Samba-read-speed-performance-tuning-td27964534.html #vfs.zfs.prefetch_disable=0 # On highload servers you may notice following message in dmesg: # "Approaching the limit on PV entries, consider increasing either the # vm.pmap.shpgperproc or the vm.pmap.pv_entry_max tunable" vm.pmap.shpgperproc=2048 loader.conf: # Accept filters for data, http and DNS requests # Useful when your software uses select() instead of kevent/kqueue or when you under DDoS # DNS accf available on 8.0+ accf_data_load="YES" accf_http_load="YES" accf_dns_load="YES" # Async IO system calls aio_load="YES" # Linux specific devices in /dev # As for 8.1 it only /dev/full #lindev_load="YES" # Adds NCQ support in FreeBSD # WARNING! all ad[0-9]+ devices will be renamed to ada[0-9]+ # 8.0+ only #ahci_load="YES" #siis_load="YES" # FreeBSD 8.2+ # New Congestion Control for FreeBSD # http://caia.swin.edu.au/urp/newtcp/tools/cc_chd-readme-0.1.txt # http://www.ietf.org/proceedings/78/slides/iccrg-5.pdf # Initial merge commit message http://www.mail-archive.com/[email protected]/msg31410.html #cc_chd_load="YES" # Increase kernel memory size to 3G. # # Use ONLY if you have KVA_PAGES in kernel configuration, and you have more than 3G RAM # Otherwise panic will happen on next reboot! # # It's required for high buffer sizes: kern.ipc.nmbjumbop, kern.ipc.nmbclusters, etc # Useful on highload stateful firewalls, proxies or ZFS fileservers # (FreeBSD 7.2+ amd64 users: Check that current value is lower!) #vm.kmem_size="3G" # If your server has lots of swap (>4Gb) you should increase following value # according to http://lists.freebsd.org/pipermail/freebsd-hackers/2009-October/029616.html # Otherwise you'll be getting errors # "kernel: swap zone exhausted, increase kern.maxswzone" # kern.maxswzone="256M" # Older versions of FreeBSD can't tune maxfiles on the fly #kern.maxfiles="200000" # Useful for databases # Sets maximum data size to 1G # (FreeBSD 7.2+ amd64 users: Check that current value is lower!) #kern.maxdsiz="1G" # Maximum buffer size(vfs.maxbufspace) # You can check current one via vfs.bufspace # Should be lowered/upped depending on server's load-type # Usually decreased to preserve kmem # (default is 10% of mem) #kern.maxbcache="512M" # Sendfile buffers # For i386 only #kern.ipc.nsfbufs=10240 # FreeBSD 9+ # HPET "legacy route" support. It should allow HPET to work per-CPU # See http://www.mail-archive.com/[email protected]/msg03603.html #hint.atrtc.0.clock=0 #hint.attimer.0.clock=0 #hint.hpet.0.legacy_route=1 # syncache Hash table tuning net.inet.tcp.syncache.hashsize=1024 net.inet.tcp.syncache.bucketlimit=512 net.inet.tcp.syncache.cachelimit=65536 # Increased hostcache # Later host cache can be viewed via net.inet.tcp.hostcache.list hidden sysctl # Very useful for it's RTT RTTVAR # Must be power of two net.inet.tcp.hostcache.hashsize=65536 # hashsize * bucketlimit (which is 30 by default) # It allocates 255Mb (1966080*136) of RAM net.inet.tcp.hostcache.cachelimit=1966080 # TCP control-block Hash table tuning net.inet.tcp.tcbhashsize=4096 # Disable ipfw deny all # Should be uncommented when there is a chance that # kernel and ipfw binary may be out-of sync on next reboot #net.inet.ip.fw.default_to_accept=1 # # SIFTR (Statistical Information For TCP Research) is a kernel module that # logs a range of statistics on active TCP connections to a log file. # See prerelease notes http://groups.google.com/group/mailing.freebsd.current/browse_thread/thread/b4c18be6cdce76e4 # and man 4 sitfr #siftr_load="YES" # Enable superpages, for 7.2+ only # Also read http://lists.freebsd.org/pipermail/freebsd-hackers/2009-November/030094.html vm.pmap.pg_ps_enabled=1 # Usefull if you are using Intel-Gigabit NIC #hw.em.rxd=4096 #hw.em.txd=4096 #hw.em.rx_process_limit="-1" # Also if you have ALOT interrupts on NIC - play with following parameters # NOTE: You should set them for every NIC #dev.em.0.rx_int_delay: 250 #dev.em.0.tx_int_delay: 250 #dev.em.0.rx_abs_int_delay: 250 #dev.em.0.tx_abs_int_delay: 250 # There is also multithreaded version of em/igb drivers can be found here: # http://people.yandex-team.ru/~wawa/ # # for additional em monitoring and statistics use # sysctl dev.em.0.stats=1 ; dmesg # sysctl dev.em.0.debug=1 ; dmesg # Also after r209242 (-CURRENT) there is a separate sysctl for each stat variable; # Same tunings for igb #hw.igb.rxd=4096 #hw.igb.txd=4096 #hw.igb.rx_process_limit=100 # Some useful netisr tunables. See sysctl net.isr #net.isr.maxthreads=4 #net.isr.defaultqlimit=4096 #net.isr.maxqlimit: 10240 # Bind netisr threads to CPUs #net.isr.bindthreads=1 # # FreeBSD 9.x+ # Increase interface send queue length # See commit message http://svn.freebsd.org/viewvc/base?view=revision&revision=207554 #net.link.ifqmaxlen=1024 # Nicer boot logo =) loader_logo="beastie" And finally here is KERNCONF: # Just some of them, see also # cat /sys/{i386,amd64,}/conf/NOTES # This one useful only on i386 #options KVA_PAGES=512 # You can play with HZ in environments with high interrupt rate (default is 1000) # 100 is for my notebook to prolong it's battery life #options HZ=100 # Polling is goot on network loads with high packet rates and low-end NICs # NB! Do not enable it if you want more than one netisr thread #options DEVICE_POLLING # Eliminate datacopy on socket read-write # To take advantage with zero copy sockets you should have an MTU >= 4k # This req. is only for receiving data. # Read more in man zero_copy_sockets # Also this epic thread on kernel trap: # http://kerneltrap.org/node/6506 # Here Linus says that "anybody that does it that way (FreeBSD) is totally incompetent" #options ZERO_COPY_SOCKETS # Support TCP sign. Used for IPSec options TCP_SIGNATURE # There was stackoverflow found in KAME IPSec stack: # See http://secunia.com/advisories/43995/ # For quick workaround you can use `ipfw add deny proto ipcomp` options IPSEC # This ones can be loaded as modules. They described in loader.conf section #options ACCEPT_FILTER_DATA #options ACCEPT_FILTER_HTTP # Adding ipfw, also can be loaded as modules options IPFIREWALL # On 8.1+ you can disable verbose to see blocked packets on ipfw0 interface. # Also there is no point in compiling verbose into the kernel, because # now there is net.inet.ip.fw.verbose tunable. #options IPFIREWALL_VERBOSE #options IPFIREWALL_VERBOSE_LIMIT=10 options IPFIREWALL_FORWARD # Adding kernel NAT options IPFIREWALL_NAT options LIBALIAS # Traffic shaping options DUMMYNET # Divert, i.e. for userspace NAT options IPDIVERT # This is for OpenBSD's pf firewall device pf device pflog # pf's QoS - ALTQ options ALTQ options ALTQ_CBQ # Class Bases Queuing (CBQ) options ALTQ_RED # Random Early Detection (RED) options ALTQ_RIO # RED In/Out options ALTQ_HFSC # Hierarchical Packet Scheduler (HFSC) options ALTQ_PRIQ # Priority Queuing (PRIQ) options ALTQ_NOPCC # Required for SMP build # Pretty console # Manual can be found here http://forums.freebsd.org/showthread.php?t=6134 #options VESA #options SC_PIXEL_MODE # Disable reboot on Ctrl Alt Del #options SC_DISABLE_REBOOT # Change normal|kernel messages color options SC_NORM_ATTR=(FG_GREEN|BG_BLACK) options SC_KERNEL_CONS_ATTR=(FG_YELLOW|BG_BLACK) # More scroll space options SC_HISTORY_SIZE=8192 # Adding hardware crypto device device crypto device cryptodev # Useful network interfaces device vlan device tap #Virtual Ethernet driver device gre #IP over IP tunneling device if_bridge #Bridge interface device pfsync #synchronization interface for PF device carp #Common Address Redundancy Protocol device enc #IPsec interface device lagg #Link aggregation interface device stf #IPv4-IPv6 port # Also for my notebook, but may be used with Opteron device amdtemp # Same for Intel processors device coretemp # man 4 cpuctl device cpuctl # CPU control pseudo-device # Support for ECMP. More than one route for destination # Works even with default route so one can use it as LB for two ISP # For now code is unstable and panics (panic: rtfree 2) on route deletions. #options RADIX_MPATH # Multicast routing #options MROUTING #options PIM # Debug & DTrace options KDB # Kernel debugger related code options KDB_TRACE # Print a stack trace for a panic options KDTRACE_FRAME # amd64-only(?) options KDTRACE_HOOKS # all architectures - enable general DTrace hooks #options DDB #options DDB_CTF # all architectures - kernel ELF linker loads CTF data # Adaptive spining in lockmgr (8.x+) # See http://www.mail-archive.com/[email protected]/msg10782.html options ADAPTIVE_LOCKMGRS # UTF-8 in console (8.x+) #options TEKEN_UTF8 # FreeBSD 8.1+ # Deadlock resolver thread # For additional information see http://www.mail-archive.com/[email protected]/msg18124.html # (FYI: "resolution" is panic so use with caution) #options DEADLKRES # Increase maximum size of Raw I/O and sendfile(2) readahead #options MAXPHYS=(1024*1024) #options MAXBSIZE=(1024*1024) # For scheduler debug enable following option. # Debug will be available via `kern.sched.stats` sysctl # For more information see http://svnweb.freebsd.org/base/head/sys/conf/NOTES?view=markup #options SCHED_STATS If you are tuning network for maximum performance you may wish to play with ifconfig options like: # You can list all capabilities via `ifconfig -m` ifconfig [-]rxcsum [-]txcsum [-]tso [-]lro mtu In case you've enabled DDB in kernel config, you should edit your /etc/ddb.conf and add something like this to enable automatic reboot (and textdump as bonus): script kdb.enter.panic=textdump set; capture on; show pcpu; bt; ps; alltrace; capture off; call doadump; reset script kdb.enter.default=textdump set; capture on; bt; ps; capture off; call doadump; reset And do not forget to add ddb_enable="YES" to /etc/rc.conf Since FreeBSD 9 you can select to enable/disable flowcontrol on your NIC: # See http://en.wikipedia.org/wiki/Ethernet_flow_control and # http://www.mail-archive.com/[email protected]/msg07927.html for additional info ifconfig bge0 media auto mediaopt flowcontrol PS. Also most of FreeBSD's limits can be monitored by # vmstat -z and # limits PPS. variety of network counters can be monitored via # netstat -s In FreeBSD-9 netstat's -Q option appeared, try following command to display netisr stats # netstat -Q PPPS. also see # man 7 tuning PPPPS. I wanted to thank FreeBSD community, especially author of nginx - Igor Sysoev, nginx-ru@ and FreeBSD-performance@ mailing lists for providing useful information about FreeBSD tuning. FreeBSD WIP * Whats cooking for FreeBSD 7? * Whats cooking for FreeBSD 8? * Whats cooking for FreeBSD 9? So here is the question: What tunings are you using on yours FreeBSD servers? You can also post your /etc/sysctl.conf, /boot/loader.conf, kernel options, etc with description of its' meaning (do not copy-paste from sysctl -d). Don't forget to specify server type (web, smb, gateway, etc) Let's share experience!

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• Linux - real-world hardware RAID controller tuning (scsi and cciss)

  - by ewwhite

  Most of the Linux systems I manage feature hardware RAID controllers (mostly HP Smart Array). They're all running RHEL or CentOS. I'm looking for real-world tunables to help optimize performance for setups that incorporate hardware RAID controllers with SAS disks (Smart Array, Perc, LSI, etc.) and battery-backed or flash-backed cache. Assume RAID 1+0 and multiple spindles (4+ disks). I spend a considerable amount of time tuning Linux network settings for low-latency and financial trading applications. But many of those options are well-documented (changing send/receive buffers, modifying TCP window settings, etc.). What are engineers doing on the storage side? Historically, I've made changes to the I/O scheduling elevator, recently opting for the deadline and noop schedulers to improve performance within my applications. As RHEL versions have progressed, I've also noticed that the compiled-in defaults for SCSI and CCISS block devices have changed as well. This has had an impact on the recommended storage subsystem settings over time. However, it's been awhile since I've seen any clear recommendations. And I know that the OS defaults aren't optimal. For example, it seems that the default read-ahead buffer of 128kb is extremely small for a deployment on server-class hardware. The following articles explore the performance impact of changing read-ahead cache and nr_requests values on the block queues. http://zackreed.me/articles/54-hp-smart-array-p410-controller-tuning http://www.overclock.net/t/515068/tuning-a-hp-smart-array-p400-with-linux-why-tuning-really-matters http://yoshinorimatsunobu.blogspot.com/2009/04/linux-io-scheduler-queue-size-and.html For example, these are suggested changes for an HP Smart Array RAID controller: echo "noop" > /sys/block/cciss\!c0d0/queue/scheduler blockdev --setra 65536 /dev/cciss/c0d0 echo 512 > /sys/block/cciss\!c0d0/queue/nr_requests echo 2048 > /sys/block/cciss\!c0d0/queue/read_ahead_kb What else can be reliably tuned to improve storage performance? I'm specifically looking for sysctl and sysfs options in production scenarios.

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• SQL SERVER – Video – Beginning Performance Tuning with SQL Server Execution Plan

  - by pinaldave

  Traveling can be most interesting or most exhausting experience. However, traveling is always the most enlightening experience one can have. While going to long journey one has to prepare a lot of things. Pack necessary travel gears, clothes and medicines. However, the most essential part of travel is the journey to the destination. There are many variations one prefer but the ultimate goal is to have a delightful experience during the journey. Here is the video available which explains how to begin with SQL Server Execution plans. Performance Tuning is a Journey Performance tuning is just like a long journey. The goal of performance tuning is efficient and least resources consuming query execution with accurate results. Just as maps are the most essential aspect of performance tuning the same way, execution plans are essentially maps for SQL Server to reach to the resultset. The goal of the execution plan is to find the most efficient path which translates the least usage of the resources (CPU, memory, IO etc). Execution Plans are like Maps When online maps were invented (e.g. Bing, Google, Mapquests etc) initially it was not possible to customize them. They were given a single route to reach to the destination. As time evolved now it is possible to give various hints to the maps, for example ‘via public transport’, ‘walking’, ‘fastest route’, ‘shortest route’, ‘avoid highway’. There are places where we manually drag the route and make it appropriate to our needs. The same situation is with SQL Server Execution Plans, if we want to tune the queries, we need to understand the execution plans and execution plans internals. We need to understand the smallest details which relate to execution plan when we our destination is optimal queries. Understanding Execution Plans The biggest challenge with maps are figuring out the optimal path. The same way the  most common challenge with execution plans is where to start from and which precise route to take. Here is a quick list of the frequently asked questions related to execution plans: Should I read the execution plans from bottoms up or top down? Is execution plans are left to right or right to left? What is the relational between actual execution plan and estimated execution plan? When I mouse over operator I see CPU and IO but not memory, why? Sometime I ran the query multiple times and I get different execution plan, why? How to cache the query execution plan and data? I created an optimal index but the query is not using it. What should I change – query, index or provide hints? What are the tools available which helps quickly to debug performance problems? Etc… Honestly the list is quite a big and humanly impossible to write everything in the words. SQL Server Performance:  Introduction to Query Tuning My friend Vinod Kumar and I have created for the same a video learning course for beginning performance tuning. We have covered plethora of the subject in the course. Here is the quick list of the same: Execution Plan Basics Essential Indexing Techniques Query Design for Performance Performance Tuning Tools Tips and Tricks Checklist: Performance Tuning We believe we have covered a lot in this four hour course and we encourage you to go over the video course if you are interested in Beginning SQL Server Performance Tuning and Query Tuning. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Execution Plan

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• Friend of Red Gate

  - by Nick Harrison

  Friend of Red Gate I recently joined the friend of Red Gate program.   I am very honored to be included in this group.    This program is a big part of Red Gates community outreach.   If you are not familiar with Red Gate, I urge you to check them out.    They have some wonderful tools for the SQL Server community and the DotNet community.    They are also building up some tools for Exchange and Oracle. I was invited to join this program primarliy because of my work with Simple Talk and promoting one of their newest products, Reflector. Reflector is a wonderful tool.   I doubt that anyone who has ever used it would argue that point. Red Gate did a wonderful job taking over the support of Reflector.   I know many people had their doubts.    The initial release under Red Gate should set those fears to rest.   I was very impressed with how their developers interacted with their users during the preview phase! Red Gate is also a good partner for the community.    They activly support the community, sponsoring Code Camps, sponsoring User Groups, supporting the Forums, etc. And their tools are pretty amazing as well.

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• Red Gate and the Community

  - by RedAndTheCommunity

  I was lucky enough to join the Communities team in April 2011, having worked in the equally awesome (but more number-crunchy), Finance team at Red Gate for about four years before that. Being totally passionate about Red Gate, and easily excitable, it seems like the perfect place to be. Not only do I get to talk to people who love Red Gate every day, I get to think up new ways to make them love us even more. Red Gate sponsored 178 SQL Server and .NET events and user group meetings in 2011. They ranged from SQL Saturdays and Code Camps to 10 person user group meetings, from California to Krakow. We've given away cash, software, Kindles, and of course swag. The Marketing Cupboard is like a wonderland of Red Gate goodies; it is guarded day and night to make sure the greedy Red Gaters don't pilfer the treasure inside. There are Red Gate yo-yos, books, pens, ice scrapers and, over the Holidays, there were some special bears. We had to double the patrols guarding the cupboard to protect them. You can see why: Over the Holidays, we gave funding and special Holiday swag (including the adorable bears), to 10 lucky user groups, who held Christmas parties - doing everything from theatre trips to going to shooting ranges. What next? So, what about this year? In 2012 our main aim is to be out there meeting more of you. So get ready to see an army of geeks in red t-shirts at your next event! We also want to do more fun things like our Christmas party giveaway. What cool ideas do you have for sponsorship in 2012? An Easter Egg hunt with SQL server clues? A coding competition? A duelling contest with a license of SQL Toolbelt for the winner? Let me know.

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• I'm Seeing Red

  - by Grant Fritchey

  Hello World! My move into the world of Red Gate is more and more complete with my shiny, new, red, blog. The goal of this blog is not to compete with, or replace, my blog over at ScaryDBA. Instead, this blog is where I can share things I find about Red Gate products and services. I can talk about the things that we're doing at Red Gate. I can talk about the things I'm doing at Red Gate. In short, this is my Red Gate blog. I'm still the Scary DBA, but over here, I'm painted bright red (and no, I was promised that no pictures were taken of that process). So look for tips and suggestions about Red Gate products, methods to help you do your job better using one of our tools, and anything else I can think of or comment on that supports you and our excellent software.

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• Tuning GlassFish for Production

  - by arungupta

  The GlassFish distribution is optimized for developers and need simple deployment and server configuration changes to provide the performance typically required for production usage. The formal Performance Tuning Guide provides an explanation of capacity planning and tuning tips for application, GlassFish, JVM, and the operating system. The GlassFish Server Control (only with the commercial edition) also comes with Performance Tuner that optimizes the runtime for optimal throughput and scalability. And then there are multiple blogs that provide more insights as well: • Optimizing GlassFish for Production (Diego Silva, Mar 2012) • GlassFish Production Tuning (Vegard Skjefstad, Nov 2011) • GlassFish in Production (Sunny Saxena, Jul 2011) • Putting GlassFish v3 in Production: Essential Surviving Guide (JeanFrancois, Nov 2009) • A GlassFish Tuning Primer (Scott Oaks, Dec 2007) What is your favorite source for GlassFish Performance Tuning ?

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• Updated copy of the OBIEE Tuning whitepaper

  - by inowodwo

  The Product Assurance team have released an updated copy of the OBIEE Tuning Whitepaper. You can find it on the PA blog https://blogs.oracle.com/pa/entry/test or via Support note OBIEE 11g Infrastructure Performance Tuning Guide (Doc ID 1333049.1) https://support.us.oracle.com/oip/faces/secure/km/DocumentDisplay.jspx?id=1333049.1&recomm=Y This new revised document contains following useful tuning items: 1.    New improved HTTP Server caching algorithm. 2.    Oracle iPlanet Web Server tuning parameters. 3.    New tuning parameters settings / values for OPIS/OBIS components.

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• need for tcp fine-tuning on heavily used proxy server

  - by Vijay Gharge

  Hi all, I am using squid like Internet proxy server on RHEL 4 update 6 & 8 with quite heavy load i.e. 8k established connections during peak hour. Without depending much on application provider's expertise I want to achieve maximum o/p from linux. W.r.t. that I have certain questions as following: How to find out if there is scope for further tcp fine-tuning (without exhausting available resources) as the benchmark values given by vendor looks poor! Is there any parameter value that is available from OS / network stack that will show me the results. If at all there is scope, how shall I identify & configure OS tcp stack parameters i.e. using sysctl or any specific parameter Post tuning how shall I clearly measure performance enhancement / degradation ?

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• Best way tuning FreeBSD router ?

  - by Mabradox

  How you tuning your freebsd router ? Any kernel options , or sysctl :)

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• Would you expect this error ?

  - by GrumpyOldDBA

  Now I know why, but what I'm thinking is that if I create an error should I get valid data returned? To explain, I was browsing through the dmvs for queries which might benefit from tuning and I identified a query with two clustered index scans ( table scans ). I don't know all the schema off by heart and I was looking for a select by a LoginID column. I assumed this would be numeric and promptly entered an integer value to examine the query plan, yeah I should have looked at the table definition...(read more)

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• IOUG SIG Webcast on October 30th : Performance Tuning your DB Cloud

  - by Anand Akela

  The Oracle Enterprise Manager Special Interest Group (SIG) is a growing body of IOUG members who manage or are interested in all aspects of Oracle Enterprise Manager. This IOUG SIG is managed by volunteers and supported by Oracle Enterprise Manager product managers and developers. The purpose of the SIG is to bring relevant information and education through webcasts, discussions and networking to users interested in learning more about the product, and to share user experiences. On October 30th at 10 AM pacific time, Oracle Enterprise Manager SIG is hosting a webcast on "Performance Tuning your DB Cloud in OEM 12c Cloud Control - 360 Degrees". In this webcast, Tariq Farooq , CEO, BrainSurface and Mike Ault, Oracle  will provide a tutorial on how to monitor and perform performance tuning of the Oracle database cloud environment. You will learn how to leverage Oracle Enterprise Manager for tuning, trouble-shooting & monitoring your Oracle Database Cloud Ecosystem. The session covers lessons learned, tips/tricks, recommendations, best practices, gotchas and a whole lot more on how to effectively use Oracle Enterprise Manager Cloud Control 12c for quick, easy & intuitive performance tuning of your Oracle Database Cloud. Session Objectives:• Leveraging OEM12c Cloud Control for Oracle DB Tuning/Monitoring • Limited Deep-Dive on AWR • Oracle DB Cloud Performance Tuning • Best Practices for DB Cloud Maintenance/Monitoring Register Now ! Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Google+ |  Newsletter

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• Windows 7 network performance tuning for LAN

  - by Hubert Kario

  I want to tune Windows 7 TCP stack for speed in a LAN environment. Bit of background info: I've got a Citrix XenServer set up with Windows 2008R2, Windows 7 and Debian Lenny with Citrix kernel, Windows machines have Tools installed the iperf server process is running on different host, also Debian Lenny. The servers are otherwise idle, tests were repeated few times to confirm results. While testing with iperf 2008R2 can achieve around 600-700Mbps with no tuning what so ever but I can't find any guide or set of parameters that will make Windows 7 achieve anything over 150Mbps with no change in TCP window size using -w parameter to iperf. I tried using netsh autotuining to disabled, experimental, normal and highlyrestricted - no change. Changing congestionprovider doesn't do anything, just as rss and chimney. Setting all the available settings to same values as on Windows 2008R2 host doesn't help. To summarize: Windows 2008R2 default settings: 600-700Mbps Debian, default settings: 600Mbps Windows 7 default settings: 120Mbps Windows 7 default, iperf -w 65536: 400-500Mbps While the missing 400Mbps in performance I blame on crappy Realtek NIC in the XenServer host (I can do ~980Mbps from my laptop to the iperf server) it doesn't explain why Windows 7 can't achieve good performance without manually tuning window size at the application level. So, how to tune Windows 7?

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• Tuning (and understanding) table_cache in mySQL

  - by jotango

  Hello, I ran the excellent MySQL performance tuning script and started to work through the suggestions. One I ran into was TABLE CACHE Current table_cache value = 4096 tables You have a total of 1073 tables. You have 3900 open tables. Current table_cache hit rate is 2%, while 95% of your table cache is in use. You should probably increase your table_cache I started to read up on the table_cache but found the MySQL documentation quite lacking. They do say to increase the table_cache, "if you have the memory". Unfortunately the table_cache variable is defined as "The number of open tables for all threads." How will the memory used by MySQL change, if I increase this variable? What is a good value, to set it to?

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• Best network tuning variables for a Linux proxy

  - by smarthall

  What are the best settings to tune so that Linux can handle a very large amount of TCP connections such as would be seen by a proxy server or a webserver? I'm using Centos6 and squid and am seeing a large amount of TIME_WAIT connections backing up until finally the machine stops responding. The machine isn't loaded at the time, and is having trouble making ingoing and outgoing connections. I've had several suggestions of tuning /proc/sys/net/ipv4/tcp_tw_reuse and /proc/sys/net/ipv4/tcp_tw_reuse but they mention bad interactions with load balancers and NAT both of which are used in my situation.

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• Red Gate does Byte Night 2012

  - by red(at)work

  On the 5th of October 2012, a team of nine plucky Red Gaters braved the howling wind and the driving rain to sleep outside. No tents or mattresses were allowed – all we took for protection were sleeping bags, groundsheets, plastic sacks and Colin’s enormous fishing umbrella (a godsend in umbrella-y disguise). Why would we do such a thing? For Byte Night, an annual tech sector sleepout in support of Action for Children, who tackle the causes as well as the consequences of youth homelessness. Byte Night encourages technology professionals to do for one night a year what thousands of young people have to do every night – sleep rough.  We signed up for Byte Night in the warm, heady midst of the British summer, thinking it couldn’t possibly be all that bad. Even on the night itself – before the rain began to fall, sat in the comfort and warmth of a company canteen, drinking wine and eating chill and preparing to win the pub quiz – we were excited and optimistic about the night that lay ahead of us. All of that changed as soon as we stepped out into one of the worst rainstorms of the year. Brian, the team’s birthday boy, describes it best: Picture the scene: it’s 3 am on a Friday. I’m lying outside, fully clothed in a sleeping bag, wearing a raincoat, trussed up inside a large plastic pocket, on a ground sheet beneath a giant umbrella, wedged so tightly between two of my colleagues that I can’t move my arms. I’m wide awake, staring up at the grey sky beyond the edge of the umbrella; a limp, flickering white glow hints at a moon somewhere behind the drifting clouds. I haven’t slept since we first moved outside at 11 pm. Outside. Did I mention we were outside? I’m hung over. I need the loo. But there is no way on earth that I’m getting out of this sleeping bag. It’s cold. It’s raining. Not just raining, but chucking it down. It’s been doing this non-stop since 10pm. The rain sounds like a hyperactive drummer on the fishing umbrella, and the noise is loud and relentless. Puddles of water are forming all over the groundsheet, and, despite being ensconced inside the plastic pouch, I am wet. The fishing umbrella is protecting me from the worst of the driving rain, but not all of me is under it, and five hours of rain is no match for it. Everything is wet. My left side has become horribly damp. My trainers, which I placed next to my sleeping bag, are now completely soaked through. Mmm. That’ll be fun in the morning. My head is next to Colin’s head on one side, and a multi-pack of McCoy’s cheddar and onion crisps on the other. Don’t ask about the tub of hummus. That’s somewhere down by my ankles, abandoned to the night. Jess, who is lying next to me, rolls over onto her side. A mini waterfall cascades from her rain-pouch onto my face. Bah. I continue to stare into the heavens, willing the dawn to hurry up. Something lands on my face. It’s a mosquito. Great. Midnight, when this still seemed like fun – when we opened some champagne and my colleagues presented me with a caterpillar birthday cake, when everyone was drunk and jolly and full of stoic resolve – feels like a long time ago. Did I mention that today is my birthday? The remains of the caterpillar cake endure the same fate as the hummus, left out in the rain like a metaphor for sadness. It’s getting colder. I can see my breath. Silence has descended on the group, apart from the rustle of plastic. And the rain, obviously. Someone snores, and I envy whoever it is the sweet escape of sleep. I try to wriggle a bit further down inside my sleeping bag, but it doesn’t want to be wriggled into. Only 3 hours till dawn. 180 minutes. I begin to count them off, one at a time.  All nine of us got to go home in the morning, but thousands of children across the UK don’t have that luxury. If you’d like to sponsor the Red Gate Byte Night team, our JustGiving page can be found here.   Chris, before the outside bit actually happened. More photos from Byte Night Cambridge 2012 can be found here.

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• Guides for PostgreSQL query tuning?

  - by Joe

  I've found a number of resources that talk about tuning the database server, but I haven't found much on the tuning of the individual queries. For instance, in Oracle, I might try adding hints to ignore indexes or to use sort-merge vs. correlated joins, but I can't find much on tuning Postgres other than using explicit joins and recommendations when bulk loading tables. Do any such guides exist so I can focus on tuning the most run and/or underperforming queries, hopefully without adversely affecting the currently well-performing queries? I'd even be happy to find something that compared how certain types of queries performed relative to other databases, so I had a better clue of what sort of things to avoid. update: I should've mentioned, I took all of the Oracle DBA classes along with their data modeling and SQL tuning classes back in the 8i days ... so I know about 'EXPLAIN', but that's more to tell you what's going wrong with the query, not necessarily how to make it better. (eg, are 'while var=1 or var=2' and 'while var in (1,2)' considered the same when generating an execution plan? What if I'm doing it with 10 permutations? When are multi-column indexes used? Are there ways to get the planner to optimize for fastest start vs. fastest finish? What sort of 'gotchas' might I run into when moving from mySQL, Oracle or some other RDBMS?) I could write any complex query dozens if not hundreds of ways, and I'm hoping to not have to try them all and find which one works best through trial and error. I've already found that 'SELECT count(*)' won't use an index, but 'SELECT count(primary_key)' will ... maybe a 'PostgreSQL for experienced SQL users' sort of document that explained sorts of queries to avoid, and how best to re-write them, or how to get the planner to handle them better. update 2: I found a Comparison of different SQL Implementations which covers PostgreSQL, DB2, MS-SQL, mySQL, Oracle and Informix, and explains if, how, and gotchas on things you might try to do, and his references section linked to Oracle / SQL Server / DB2 / Mckoi /MySQL Database Equivalents (which is what its title suggests) and to the wikibook SQL Dialects Reference which covers whatever people contribute (includes some DB2, SQLite, mySQL, PostgreSQL, Firebird, Vituoso, Oracle, MS-SQL, Ingres, and Linter).

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• border:2px solid red VS border:2px red solid

  - by metal-gear-solid

  Are both method valid? both works same. border:2px solid red; and border:2px red solid;

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• That’s a wrap! Almost, there’s still one last chance to attend a SQL in the City event in 2012

  - by Red and the Community

  The communities team are back from the SQL in the City multi-city US Tour and we are delighted to have met so many happy SQL Server professionals and Red Gate customers. We set out to run a series of back-to-back events in order to meet, talk to and delight as many SQL Server and Red Gate enthusiasts as possible in 5 different cities in 11 days. We did it! The attendees had a good time too and 99% of them would attend another SQL in the City event in 2013 – so it seems we left an impression. There were a range of topics on the event agenda, ranging from ‘The Whys & Hows of Continuous Integration’, ‘Database Maintenance Essentials’, ‘Red Gate tools – The Complete Lifecycle’, ‘Automated Deployment: Application And Database Releases Without The Headache’, ‘The Ten Commandments of SQL Server Monitoring’ and many more. Videos and slides from the events will be posted to the event website in November, after our last event of 2012. SQL in the City Seattle – November 5 Join us for free and hear from some of the very best names in the SQL Server world. SQL Server MVPs such as; Steve Jones, Grant Fritchey, Brent Ozar, Gail Shaw and more will be presenting at the Bell Harbor conference center for one day only. We’re even taking on board some of the recent attendee-suggestions of how we can improve the events (feedback from the 65% of attendees who came to our US tour events), first off we’re extending the drinks celebration in the evening! Rather than just a 30 minute drink and run, attendees will have up to 2 hours to enjoy free drinks, relax and network in a fantastic environment amongst some really smart like-minded professionals. If you’re interested in expanding your SQL Server knowledge, would like to learn more about Red Gate tools, get yourself registered for the last SQL in the City event of 2012. It’s free, fun and we’re very friendly! I look forward to seeing you in Seattle on Monday November 5. Cheers, Annabel.

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• SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

  - by Pinal Dave

  Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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