Whenever a valid SQL statement is processed Oracle has to decide how to retrieve the necessary data. This decision can be made using one of two methods: Rule Based Optimizer (RBO) - This method is used if the server has no internal statistics relating to the objects referenced by the statement. This method is no longer favoured by Oracle and will be desupported in future releases.Cost Based Optimizer (CBO) - This method is used if internal statistics are present. The CBO checks several possible execution plans and selects the one with the lowest cost, where cost relates to system resources.An oracle CBO will have a knock on effect if an oracle init parameter optimizer_index_cost_adj is set to a wrong value. I came across this issue while working with a media client using SAP CRM/BW applications on top of oracle database layer. The total database size was in excess of 4 tera Bytes.I have picked up a worst performing SQL for analysis here. A view ""VBAP_VAPMA" is based on VBAP and VAPMA tables, VBAP listed in top wait segments consistently. I could see optimizer_index_cost_adj is favouring index scans even if they are worst performer over FULL table scan. I have done some calculations to prove the point.SELECT "AEDAT", "AUART", "ERDAT", "ERNAM", "KONDM", "KUNNR", "MATKL", "MATNR", "NETWR", "POSNR", "VBELN", "VKORG", "WAERK", "ZZAD_LINE_STATUS", "ZZCDO", "ZZCDO_P", "ZZKONDM_P"FROM SAPR3."VBAP_VAPMA"WHERE "MANDT" = :a0AND "AEDAT" > :a1AND "AUART" = :a2AND "KONDM" = :a3AND "VKORG" = :a4AND "ZZCDO" >= :a5Current value Optimizer_index_cost_adj is set for 10. Setting "Optimizer_index_cost_adj=100 changes execution plan from index "VBAP~Z3" to Full table scan.Optimizer_index_cost_adj=10SELECT STATEMENT Optimizer Mode=CHOOSE 2 313894 TABLE ACCESS BY INDEX ROWID SAPR3.VAPMA 1 49 .4 NESTED LOOPS 2 206 313893.8 TABLE ACCESS BY INDEX ROWID SAPR3.VBAP 3 K 174 K 312568.2 INDEX RANGE SCAN SAPR3.VBAP~Z3 15 M 100758 INDEX RANGE SCAN SAPR3.VAPMA~Z01 1 3Optimizer_index_cost_adj=100 (Oracle recommended Default Value)SELECT STATEMENT Optimizer Mode=CHOOSE 2 577409TABLE ACCESS BY INDEX ROWID SAPR3.VAPMA 1 49 4NESTED LOOPS 2 206 577409 TABLE ACCESS FULL SAPR3.VBAP 3 K 174 K 564153 INDEX RANGE SCAN SAPR3.VAPMA~Z01 1 3I will do simple calculations on how Oracle is estimating execution costs here. Please note these are not precise formulas.Approx Full Table Scan Cost : 484,193 UnadjustedCost here is calculated as "IO + CPU/1000 + NetIO*1.5" but a simple formula would be (No of blocks/DB_FILE_MULTIBLOCK_READCOUNT)(No of blocks/DB_FILE_MULTIBLOCK_READCOUNT)= 3,873,549 blocks/8 = 484,193How to drop execution cost : Increase DB_FILE_MULTIBLOCK_READCOUNT to 32 + Reorg of table , cost of "FULL Scan" will drop to 82,000 giving 5 fold increase in IO.Cost of an Index Scan : 149,483 is Adjusted valueIt is using a non-unique index "SAPR3.VBAP~Z3" defined on columns MANDT, ZZBU_DIR, ZZBU_EDITION.There are only 160 distinct values on this index out of 15.9 million rows - "select MANDT, ZZBU_DIR, ZZBU_EDITION from SAPR3.vbap"Index Range Scan Cost = blevel + (Avg leaf blk per key * (num_rows * selectivity))= 1,188,451 (Actual Value) > than FTSWe have set Optimizer_index_cost_adj=10 so real cost we set is = 1,188,451*10/100= 118845.1 which is 10% of actual overheadFinal value of index cost must include efforts for accessing data blocks =Previous Cost + (Avg_data_blks_per_key * (Clustering_fact / Total Table blks))= 149,483Conclusion:We need to let oracle optimizer decide a best path for execution than forcing it to choose indexes all the time. Putting default value for "optimizer_index_cost_adj" must be followed with up-to-date stats as cost based optmizer is heavily dependent on right stats.http://OracleDbaSupport.co.uk is a blog site of Sagar Patil, an independent oracle consultant with a great understanding of how the Oracle database engine & Oracle Applications work together.
Some day you will surely forget about the important matter.Screen Calendar, a Windows 98/Me/NT/2k/XP utility that lets you add PIM like calendar just on any wallpapers.Screen Calendar software really allows you to make your own calendar and put the calendar on your desktop wallpaper choosing the calendar size and transparency. You can add schedule calendar events. Double-click a calendar to schedule your business day. To read your records fully, just move your mouse over the date cell. Also, your records and calendar can be printed with a background image (JPG, BMP and PNG image formats are supported). Screen Calendar runs in system tray so your PIM is always at hand.
Beginning with version 7.2, you can attach any files to your daily records.
The program changes the desktop look quite easily: choose a new skin or calendar arrangement and font or even set a random background calendar image. To add new skins simple click any skin link athttp://www.screencalendar.com and the one will be installed automatically. Also, the well-dressed desktop calendar is wearing elegant WinAmp skins.Screen Calendar does not request the Active Desktop enable but the calendar is really active on your desktop.
Screen Calendar costs $24.95 for a single-user license. The trial version of Screen Calendar is free and fully-functional but the registration reminder screen will pop up.
Setting up a profitable database for your business requires a well-designed jewelry software program. But how do you tell if a jewelry software program is well designed? Here are a few questions to ask before making a purchase. Is the jewelry software program easy to learn and use? Has the program been around long enough to be fully field-tested in a number of retail jewelry stores? Is the program constantly updated to meet new marketing challenges, changing retail conditions and tax reporting requirements?Once you have purchased a jewelry software program, its time to decide what information to cultivate.The Database is Only as Good as the Information You CollectYou probably wont want to collect all the data your jewelry software is designed to collect. Just because a program is able to accumulate a lot of different information, doing so can turn an easy job into a difficult one. By the same token, keep the future in mind. Sometimes information that is not needed today may become important later on. So look ahead when planning how to use your jewelry software, but dont fall into the trap of information overload.Start with the most essential data that should be stored in your jewelry software. This will probably be: Customer contact information Product or Services purchased Purchase price and picture of an item InventoryWhen setting up your customer contact information, be certain to include e-mails. Even if you dont have a use for them right now, they may turn out to be gold in the future. Plus they are easy to add to any jewelry software customer database.Other information you may want to include in your jewelry software database might be: Information requested and provided to a customer Warranties or insurance purchased (if applicable) Any gem quality disclosures discussed.A good jewelry software program will also allow you to collect specialized information that might be applicable to just your store. If you have such a need and dont know how to incorporate it into your jewelry software, contact the programs customer support.Once You Begin Collecting Data in Your Jewelry Software Program ...Use It!Nothing is more useless than a lot of information sitting idle in a jewelry software program. Use it to plan and execute advertising programs...control inventory...order new items...and help make other business decisions. Get in the habit of using your jewelry software everyday and it will quickly become one of your best and most profitable business partners.
Anti-spyware is software that protects computer users from spyware and other unwanted software. Anti-spyware programs secure the computers against the effort of malicious spyware, to take partial control of, or intercept a computers operation without the users consent or knowledge. Anti-spyware programs offer real time protection, and scanning and removal. Real time protection functions similar to real time anti-virus protection. That is, the program monitors all incoming data by scanning all the files that the user tries to download from the Internet, and blocks the activity of components that represent spyware. Real time protection also blocks any unauthorized attempts made to install startup programs or to change the browser settings. The scanning and removal features offered by most anti-spyware programs are simple. The program scans the contents of the operating system files, Windows registry, and installed programs and removes any entry or file which tallies with those in the already existing list of identified spyware components. Anti-spyware programs also require a frequently updated database of latest spyware components. Whenever a new spyware is released, the anti-spyware developers discover and evaluate them, and create definitions or signatures which help the anti-spyware programs to identify and remove the spyware. Hence, it is highly recommended to update the anti-spyware program frequently to ensure protection. Major anti-virus firms including McAfee, Symantec, and Sophos have added anti-spyware features to their existing anti-virus products. Anti-spyware programs of recognized companies are usually not available for free use; occasionally the manufacturers allow a free trial, enabling only certain features. Very often they only provide free scanning; the actual removal of the spyware is possible only with a registered version of the product. Because fake anti-spyware programs that are actually spyware exist, one should not be put off by the price of legitimate software and the protection it offers.
There are many websites online that offer free screensavers for download. The question remains though, are those screensavers safe? By downloading and installing these so called "free screensavers" will any harm come to your computer? This is a legitimate concern, which needs to be addressed before any user even thinks about installing a free screensaver.There are several malicious programs which can come bundled with a free screensaver. These will mainly be viruses, spyware, adware, and toolbars. There are a few variations within these programs, but in the main they are considered undesirable, unless the user specifically requests them. And out of that list, the only one that you would even consider installing would be a friendly toolbar. But more on that later.Below is a brief run-down of each type of malicious programs that you would want to avoid:Viruses: These must be avoided at all costs as they can detrimentally harm your computer, often to the point of losing unrecoverable data. If you are afraid of being infected with viruses, only download software from trusted sites where programs are verified and tested, such as at Download.com. Download.com also host their own files, which means that software cannot be altered at a later date to include any viruses.Spyware: These are programs which are used to unethically track and spy on your internet online activities. The data can then be sold to advertisers or used to change your browser and computer functions. Spyware is one of the worst type of bundled software, and can be difficult to remove.Adware: Adware is a little less scary than spyware, though no less annoying to the average computer user. Adware programs will continually display popups and unwanted adverts while you are browsing. Sometimes you may not even realise that you have adware unless you notice an excessive amount of popups during your normal surfing (where there were no popups before).Toolbars: Finally we have toolbars, which is a mixed basket. Some toolbars are actually quite useful, such as the Google Toolbar, or some that offer increased entertainment experience like the StumbleUpon toolbar. Having said that, there are other toolbars which are used as a means of displaying ads and are hard to uninstall. Some of these unwanted toolbars come bundled with free screensavers or software, often from some so called big name companies.It is extremely important that you do your research before you download screensavers. Read the Terms of Service, and Conditions of Use on the websites, as companies are required by law to inform users what they would be installing.Make sure you read the fine print. Not just what is on the download page. Sometimes they will say No spyware, but they do not mention anything about adware. Are you prepared to put up with some (or a lot) of advertisements for a free screensaver? Most people certainly should not.