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  • How do I efficiently write a "toggle database value" function in AJAX?

    - by AmbroseChapel
    Say I have a website which shows the user ten images and asks them to categorise each image by clicking on buttons. A button for "funny", a button for "scary", a button for "pretty" and so on. These buttons aren't exclusive. A picture can be both funny and scary. The user clicks the "funny" button. An AJAX request is sent off to the database to mark that image as funny. The "funny" button lights up, by assigning a class in the DOM to mark it as "on". But the user made a mistake. They meant to hit the next button over. They should click "funny" again to turn it off, right? At this point I'm not sure whats the most efficient way to proceed. The database knows that the "funny" flag is set, but it's inefficient to query the database every time a button is clicked to say, is this flag set or not, then go on with a second database call to toggle it. Should I infer the state of the database flag from the DOM, i.e. if that button has the class "on" then the flag must be set, and branch at that point? Or would it be better to have a data structure in Javascript in the page which duplicates the state of each image in the database, so that every time I set the database flag to true, I also set the value in the Javascript data to true and so on?

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  • VLOOKUP in Excel, part 2: Using VLOOKUP without a database

    - by Mark Virtue
    In a recent article, we introduced the Excel function called VLOOKUP and explained how it could be used to retrieve information from a database into a cell in a local worksheet.  In that article we mentioned that there were two uses for VLOOKUP, and only one of them dealt with querying databases.  In this article, the second and final in the VLOOKUP series, we examine this other, lesser known use for the VLOOKUP function. If you haven’t already done so, please read the first VLOOKUP article – this article will assume that many of the concepts explained in that article are already known to the reader. When working with databases, VLOOKUP is passed a “unique identifier” that serves to identify which data record we wish to find in the database (e.g. a product code or customer ID).  This unique identifier must exist in the database, otherwise VLOOKUP returns us an error.  In this article, we will examine a way of using VLOOKUP where the identifier doesn’t need to exist in the database at all.  It’s almost as if VLOOKUP can adopt a “near enough is good enough” approach to returning the data we’re looking for.  In certain circumstances, this is exactly what we need. We will illustrate this article with a real-world example – that of calculating the commissions that are generated on a set of sales figures.  We will start with a very simple scenario, and then progressively make it more complex, until the only rational solution to the problem is to use VLOOKUP.  The initial scenario in our fictitious company works like this:  If a salesperson creates more than $30,000 worth of sales in a given year, the commission they earn on those sales is 30%.  Otherwise their commission is only 20%.  So far this is a pretty simple worksheet: To use this worksheet, the salesperson enters their sales figures in cell B1, and the formula in cell B2 calculates the correct commission rate they are entitled to receive, which is used in cell B3 to calculate the total commission that the salesperson is owed (which is a simple multiplication of B1 and B2). The cell B2 contains the only interesting part of this worksheet – the formula for deciding which commission rate to use: the one below the threshold of $30,000, or the one above the threshold.  This formula makes use of the Excel function called IF.  For those readers that are not familiar with IF, it works like this: IF(condition,value if true,value if false) Where the condition is an expression that evaluates to either true or false.  In the example above, the condition is the expression B1<B5, which can be read as “Is B1 less than B5?”, or, put another way, “Are the total sales less than the threshold”.  If the answer to this question is “yes” (true), then we use the value if true parameter of the function, namely B6 in this case – the commission rate if the sales total was below the threshold.  If the answer to the question is “no” (false), then we use the value if false parameter of the function, namely B7 in this case – the commission rate if the sales total was above the threshold. As you can see, using a sales total of $20,000 gives us a commission rate of 20% in cell B2.  If we enter a value of $40,000, we get a different commission rate: So our spreadsheet is working. Let’s make it more complex.  Let’s introduce a second threshold:  If the salesperson earns more than $40,000, then their commission rate increases to 40%: Easy enough to understand in the real world, but in cell B2 our formula is getting more complex.  If you look closely at the formula, you’ll see that the third parameter of the original IF function (the value if false) is now an entire IF function in its own right.  This is called a nested function (a function within a function).  It’s perfectly valid in Excel (it even works!), but it’s harder to read and understand. We’re not going to go into the nuts and bolts of how and why this works, nor will we examine the nuances of nested functions.  This is a tutorial on VLOOKUP, not on Excel in general. Anyway, it gets worse!  What about when we decide that if they earn more than $50,000 then they’re entitled to 50% commission, and if they earn more than $60,000 then they’re entitled to 60% commission? Now the formula in cell B2, while correct, has become virtually unreadable.  No-one should have to write formulae where the functions are nested four levels deep!  Surely there must be a simpler way? There certainly is.  VLOOKUP to the rescue! Let’s redesign the worksheet a bit.  We’ll keep all the same figures, but organize it in a new way, a more tabular way: Take a moment and verify for yourself that the new Rate Table works exactly the same as the series of thresholds above. Conceptually, what we’re about to do is use VLOOKUP to look up the salesperson’s sales total (from B1) in the rate table and return to us the corresponding commission rate.  Note that the salesperson may have indeed created sales that are not one of the five values in the rate table ($0, $30,000, $40,000, $50,000 or $60,000).  They may have created sales of $34,988.  It’s important to note that $34,988 does not appear in the rate table.  Let’s see if VLOOKUP can solve our problem anyway… We select cell B2 (the location we want to put our formula), and then insert the VLOOKUP function from the Formulas tab: The Function Arguments box for VLOOKUP appears.  We fill in the arguments (parameters) one by one, starting with the Lookup_value, which is, in this case, the sales total from cell B1.  We place the cursor in the Lookup_value field and then click once on cell B1: Next we need to specify to VLOOKUP what table to lookup this data in.  In this example, it’s the rate table, of course.  We place the cursor in the Table_array field, and then highlight the entire rate table – excluding the headings: Next we must specify which column in the table contains the information we want our formula to return to us.  In this case we want the commission rate, which is found in the second column in the table, so we therefore enter a 2 into the Col_index_num field: Finally we enter a value in the Range_lookup field. Important:  It is the use of this field that differentiates the two ways of using VLOOKUP.  To use VLOOKUP with a database, this final parameter, Range_lookup, must always be set to FALSE, but with this other use of VLOOKUP, we must either leave it blank or enter a value of TRUE.  When using VLOOKUP, it is vital that you make the correct choice for this final parameter. To be explicit, we will enter a value of true in the Range_lookup field.  It would also be fine to leave it blank, as this is the default value: We have completed all the parameters.  We now click the OK button, and Excel builds our VLOOKUP formula for us: If we experiment with a few different sales total amounts, we can satisfy ourselves that the formula is working. Conclusion In the “database” version of VLOOKUP, where the Range_lookup parameter is FALSE, the value passed in the first parameter (Lookup_value) must be present in the database.  In other words, we’re looking for an exact match. But in this other use of VLOOKUP, we are not necessarily looking for an exact match.  In this case, “near enough is good enough”.  But what do we mean by “near enough”?  Let’s use an example:  When searching for a commission rate on a sales total of $34,988, our VLOOKUP formula will return us a value of 30%, which is the correct answer.  Why did it choose the row in the table containing 30% ?  What, in fact, does “near enough” mean in this case?  Let’s be precise: When Range_lookup is set to TRUE (or omitted), VLOOKUP will look in column 1 and match the highest value that is not greater than the Lookup_value parameter. It’s also important to note that for this system to work, the table must be sorted in ascending order on column 1! If you would like to practice with VLOOKUP, the sample file illustrated in this article can be downloaded from here. Similar Articles Productive Geek Tips Using VLOOKUP in ExcelImport Microsoft Access Data Into ExcelImport an Access Database into ExcelCopy a Group of Cells in Excel 2007 to the Clipboard as an ImageShare Access Data with Excel in Office 2010 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Quickly Schedule Meetings With NeedtoMeet Share Flickr Photos On Facebook Automatically Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition

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  • ODI - Creating a Repository in a 12c Pluggable Database

    - by David Allan
    To install ODI 11g into an Oracle 12c pluggable database, one way is to connect using a TNS string to the pluggable database service that is executing. For example when I installed my master repository, I used a JDBC URL such as; jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=mydbserver)(PORT=1522)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=PDBORA12.US.ORACLE.COM)))   I used the above approach rather than the host:port:sid which is a common mechanism many users use to quickly get up and going. Below you can see the repository creation wizard in action, I used the 11g release and simply installed the master and work repository into my pluggable database. Be wise with your repository IDs, I simply used the default, but you should be aware that these are key in larger deployments. The database in 12c has much more tighter control on users and resources, so just getting the user creating with sufficient resource on tablespaces etc in 12c was a little more work. Once you have the repositories up and running, then the fun starts using the 12c features. More to come.

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  • Database Developers Can Now Save 20%

    - by stephen.garth
    Database developers can now increase productivity and save money at the same time. For a limited time, Oracle Store is offering a 20% discount on Oracle SQL Developer Data Modeler. Just enter the code SQLDDM at checkout to get the discount. Oracle SQL Developer Data Modeler is an independent, standalone product with a full spectrum of data and database modeling tools and utilities, including modeling for Entity Relationship Diagrams (ERD), Relational (database design), Data Type and Multi-dimensional modeling, full forward and reverse engineering and DDL code generation. SQL Developer Data Modeler can connect to any supported Oracle Database and is platform independent. Save 20% on Oracle SQL Developer Data Modeler at Oracle Store - Discount Code SQLDDM Find out more about Oracle SQL Developer and Oracle SQL Developer Data Modeler var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-13185312-1"); pageTracker._trackPageview(); } catch(err) {}

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  • HealthSouth Upgrades to Oracle Database 11g Release 2 and Oracle RAC

    - by jenny.gelhausen
    HealthSouth Corporation, the nation's largest provider of inpatient rehabilitation services, has upgraded to Oracle Database 11g Release 2 underneath PeopleSoft Enterprise Human Capital Management. Additionally, HealthSouth improved the availability and performance of its Oracle PeopleSoft Enterprise applications and Enterprise Data Warehouse using Oracle Database 11g and Oracle Real Application Clusters. Oracle Database options -- Oracle Advanced Compression and Oracle Partitioning are key to HealthSouth's data lifecycle management practices and to utilizing storage systems more efficiently. Using compression on both partitioned as well as non-partitioned tables in its data warehouse, HealthSouth has seen a 4X storage reduction without any cost to performance. "Oracle Database 11g, along with Oracle Real Application Clusters, Advanced Compression and Partitioning, all lend themselves to delivering highly available, performant data warehousing," said Henry Lovoy, Data Manager, HealthSouth Corporation. Press Release var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-13185312-1"); pageTracker._trackPageview(); } catch(err) {}

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  • Oracle Database 12c By Example – SQL Developer and Multitenant

    - by thatjeffsmith
    As you may have heard, Oracle Database 12c is now available. In addition to the binaries and docs going out, we also published a few new Oracle By Example (OBE) chapters. You can find those links here on our product page. Do you know who found these, practically the minute they were published? An enterprising DBA-extraordinaire who was just happening to be presenting at the ODTUG KScope13 conference in New Orleans. He thought it would be a good idea to download the new software over a hotel WIFI, install and create a new multitenant database, watch a few OBEs, and then demo that live for his ‘SQL Developer for DBAs‘ session. Pretty crazy, right? Well, he did it, and I was there to watch. Way cool. You can listen to @leight0nn tell his story in his own words via this ODTUG interview with @oraclenered. In case you’re too giddy to sit through the video, I’ll give you a preview – he succesfully cloned a pluggable database in about a minute with only a couple of clicks using Oracle SQL Developer 3.2.20.09 while connected to a 12c database.

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  • Join Oracle Database at Microsoft TechEd next week.

    - by Mandy Ho
    For the past nine years, Oracle has been a proud sponsor of Microsoft TechEd. TechEd is Mircosoft's premier technology conference for IT professionals and developers. This year, Oracle will demonstrate its latest database software for MS Windows, including Oracle Database 11g Enterprise and Express editions, TimesTen and MySQL.  Developers can learn how to develop .Net applications for the Oracle Database using the latest technologies, such as Entity Framework, LINQ and WCF Data Services. Attendees can also learn the new MySQL features enabling rapid installation, GUI Based application design, backup & recovery and much more within a Windows environment. Oracle will have a BOF (Birds of a Feather Session) on Tuesday, June 12, from 3:15 to 4:30. The topic will be Big Data: The Next Frontier for Innovation, Competition and Productivity. Otherwise you can visit Oracle everyday during the expo hours from Mon, June 11 to Thursday, June 14 at our booth #613. Talk to experts on TimesTen and MySQL on Windows and .NET. Also, we will have our 3D interactive demos on Oracle's engineered systems showing off Oracle Exadata, Database Appliance and more. Visit  http://northamerica.msteched.com/ for more information. 

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  • Announcing Oracle Database Mobile Server 11gR2

    - by Eric Jensen
    I'm pleased to announce that Oracle Database Mobile Server 11gR2 has been released. It's available now for download by existing customers, or anyone who wants to try it out. New features include: Support for J2ME platforms, specifically CDC platforms including OJEC(this is in addition to our existing support for Java SE and SE Embedded) Per-application integration with Berkeley DB on Android Server-side support for Apache TomEE platform Adding support for Oracle Java Micro Edition Embedded Client (OJEC for short) is an important milestone for us; it enables Database Mobile Server to work with any of the incredibly wide array of devices that run J2ME. In particular, it enables management of  networks of embedded devices, AKA machine to machine (M2M) networks. As these types of networks become more common in areas like healthcare, automotive, and manufacturing, we're seeing demand for Database Mobile Server from new and different areas. This is in addition to our existing array of mobile device use cases. The Android integration feature with Berkeley DB represents the completion of phase I of our Android support plan, we now offer a full set of sync, device and app management features for that platform. Going forward, we plan to continue the dual-focus approach, supporting mobile platforms such as Android, and iOS (hint) on the one hand, and networks of embedded M2M devices on the other. In either case, Database Mobile Server continues to be the best way to connect data-driven applications to an Oracle backend.

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  • Flashback Database

    - by Sebastian Solbach (DBA Community)
    Flashback Database bezeichnet die Funktionalität der Oracle Datenbank, die Datenbank zeitlich auf einen bestimmten Punkt, respektive eine bestimmte System Change Number (SCN) zurücksetzen zu können - vergleichbar mit einem Rückspulknopf eines Kassettenrekorders oder der Rücksetztaste eines CD-Players. Mag dieses Vorgehen bei Produktivsystemen eher selten Einsatz finden, da beim Rücksetzten alle Daten nach dem zurückgesetzten Zeitpunkt verloren wären (es sei denn man würde dieser vorher exportieren), gibt es gerade für Test- oder Standby Systeme viele Einsatzmöglichkeiten: Rücksetzten des Systems bei fehlgeschlagenen Applikations-Upgrade Alternatives Point in Time Recovery (PITR) mit anschließendem Roll Forward (besonders geeignet bei Standby Systemen) Testdatenbank mit definiertem, reproduzierbaren Ausgangspunkt (z.B. für Real Application Testing) Datenbank Upgrade Test Einige bestehende Datenbank Funktionalitäten verwenden Flashback Database implizit: Snapshot Standby Reinstanziierung der Standby (z.B. bei Fast Start Failover) Obwohl diese Funktionalität gerade für Standby Systeme und Testsysteme bestens geeignet ist, gibt es eine gewisse Zurückhaltung Flashback Database einzusetzen. Eine Ursache ist oft die Angst vor zusätzlicher Last, die das Schreiben der Flashback Logs erzeugt, sowie der zusätzlich benötigte Plattenplatz. Dabei ist die Last im Normalfall relativ gering (ca. 5%) und auch der zusätzlich benötigte Platz für die Flashback Logs lässt sich relativ genau bestimmen. Ebenfalls wird häufig nicht beachtet, dass es auch ohne das explizite Einschalten der Flashback Logs möglich ist, einen garantieren Rücksetzpunkt (Guaranteed Restore Point kurz GRP) festzulegen, und die Datenbank dann auf diesen Restore Point zurückzusetzen. Das Setzen eines garantierten Rücksetzpunktes funktioniert in 11gR2 im laufenden Betrieb. Wie dies genau funktioniert, welche Unterschiede es zum generellen Einschalten von Flashback Logs gibt, wie man Flashback Database monitoren kann und was es sonst noch zu berücksichtigen gibt, damit beschäftigt sich dieser Tipp.

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  • Oracle NoSQL Database: Cleaner Performance

    - by Charles Lamb
    In an earlier post I noted that Berkeley DB Java Edition cleaner performance had improved significantly in release 5.x. From an Oracle NoSQL Database point of view, this is important because Berkeley DB Java Edition is the core storage engine for Oracle NoSQL Database. Many contemporary NoSQL Databases utilize log based (i.e. append-only) storage systems and it is well-understood that these architectures also require a "cleaning" or "compaction" mechanism (effectively a garbage collector) to free up unused space. 10 years ago when we set out to write a new Berkeley DB storage architecture for the BDB Java Edition ("JE") we knew that the corresponding compaction mechanism would take years to perfect. "Cleaning", or GC, is a hard problem to solve and it has taken all of those years of experience, bug fixes, tuning exercises, user deployment, and user feedback to bring it to the mature point it is at today. Reports like Vinoth Chandar's where he observes a 20x improvement validate the maturity of JE's cleaner. Cleaner performance has a direct impact on predictability and throughput in Oracle NoSQL Database. A cleaner that is too aggressive will consume too many resources and negatively affect system throughput. A cleaner that is not aggressive enough will allow the disk storage to become inefficient over time. It has to Work well out of the box, and Needs to be configurable so that customers can tune it for their specific workloads and requirements. The JE Cleaner has been field tested in production for many years managing instances with hundreds of GBs to TBs of data. The maturity of the cleaner and the entire underlying JE storage system is one of the key advantages that Oracle NoSQL Database brings to the table -- we haven't had to reinvent the wheel.

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  • SQL Server Database Settings

    - by rbishop
    For those using Data Relationship Management on Oracle DB this does not apply, but for those using Microsoft SQL Server it is highly recommended that you run with Snapshot Isolation Mode. The Data Governance module will not function correctly without this mode enabled. All new Data Relationship Management repositories are created with this mode enabled by default. This mode makes SQL Server (2005+) behave more like Oracle DB where readers simply see older versions of rows while a write is in progress, instead of readers being blocked by locks while a write takes place. Many common sources of deadlocks are eliminated. For example, if one user starts a 5 minute transaction updating half the rows in a table, without snapshot isolation everyone else reading the table will be blocked waiting. With snapshot isolation, they will see the rows as they were before the write transaction started. Conversely, if the readers had started first, the writer won't be stuck waiting for them to finish reading... the writes can begin immediately without affecting the current transactions. To make this change, make sure no one is using the target database (eg: put it into single-user mode), then run these commands: ALTER DATABASE [DB] SET ALLOW_SNAPSHOT_ISOLATION ONALTER DATABASE [DB] SET READ_COMMITTED_SNAPSHOT ON Please make sure you coordinate with your DBA team to ensure tempdb is appropriately setup to support snapshot isolation mode, as the extra row versions are stored in tempdb until the transactions are committed. Let me take this opportunity to extremely strongly highly recommend that you use solid state storage for your databases with appropriate iSCSI, FiberChannel, or SAN bandwidth. The performance gains are significant and there is no excuse for not using 100% solid state storage in 2013. Actually unless you need to store petabytes of archival data, there is no excuse for using hard drives in any systems, whether laptops, desktops, application servers, or database servers. The productivity benefits alone are tremendous, not to mention power consumption, heat, etc.

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  • Service Catalogs for Database as a Service

    - by B R Clouse
    At the end of last month, I had the opportunity to present a speaking session at Oracle OpenWorld: Database as a Service: Creating a Database Cloud Service Catalog.  The session was well-attended which would have surprised me several months ago when I started researching this topic.  At that time, I thought of service catalogs as something trivial which could be explained in a few simple slides.  But while looking at all the different options and approaches available, I came to learn that designing a succinct and effective catalog is not a trivial task, and mistakes can lead to confusion and unintended side effects.  And when the room filled up, my new point of view was confirmed. In case you missed the session, or were able to attend but would like more details, I've posted a white paper that covers the topics from the session, and more.  We start with an overview of the components of a service catalog: And then look at several customer case studies of service catalogs for DBaaS.  Synthesizing those examples, we summarize the main options for defining the service categories and their levels.  We end with a template for defining Bronze | Silver | Gold service tiers for Oracle Database Services. The paper is now available here - watch for updates as we work to expand some sections and incorporate readers' feedback (hint - that includes your feedback). Visit our OTN page for additional Database Cloud collateral.

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  • Effects of internet connection speeds on server queries

    - by SephMerah
    Can my internet connection significantly effect queries run on phpmyadmin? I am currently 18 down and 30 up. I switched internet connections today and noticed a deep drop in query performance. The query that I am running is SELECT * FROM table. Simple. The table has one row of data. The MySQL server is on the same server as everything else. It is a VPS. Godaddy hosts. I dont have any other information. Centos 6.3 MySQL 5.1 PhpMyAdmin 3.4 Okay used google tools to inspect the XHR going out and coming in and this is what it reported. {"success":true,"message":"<div class=\"success\">Your SQL query has been executed successfully ( Query took 0.0033 sec )<\/div>","sql_query":"<div id=\"result_query\" align=\"\">\n<div class=\"success\">Your SQL query has been executed successfully ( Query took 0.0033 sec ) SNIP..................."}. So apparently my server is fine. The strange thing is though.. The returned XHR comes back exactly as soon as I execute the query on the page. It comes back within less than a second. Why PhpMyadmin does not report the change immediately. I am going to try a re-install.

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  • How do I encapsulate the application server from the web and database servers?

    - by SNyamathi
    So I've been doing some reading and it seems like the best practice would be to have separate database, application, and web servers. There are a few things that I've failed to understand - please feel free to recommend any reading materials that would address these topics. Database (assume MySQL) Application server communication: Does the database server do any sort of checks on the SQL commands sent / returned, or is it just a "dumb pipe" that responds to SQL commands by spitting back data? Application server (assume Tomcat) Web Server Almost the reverse here, is it the web server that is more of a pipe to the internet that forwards requests to the application server and spits back responses? I'm not wording this well, but I'm trying to ask - is it the application server that is responsible for validating data received by from requests? ex: Parsing POSTs Validating user logins Encrypting decrypting data Furthermore, how do these two servers communicate? I'm trying to keep things as flexible as possible here, so while I could write a web server in Java and use Java to communicate between the web and app server, that doesn't sound very modular. What if I want to use Python or some other language to replace the web server later on? What if I want to make a non-web facing application used in house written in C++ or something.

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  • What is the typical maximum number of database connections for Oracle running on Windows server ?

    - by Sake
    We are maintaining a database server that serve a large number of clients. Each client typically running serveral client-applications. The total number of connections to the database server (Oracle 9i) is reaching 800 connections on peak load. The windows 2003 server is starting to run out of memory. We are now planning to move to 64bit Windows in order to gain higher memory capability. As a developer I suggest moving to multi-tier architecture with conneciton pooling, which I believe is a natural solution to this problem. However, in order to support my idea, I want the information on: what exactly is the typical number of connections allowed for Oracle database ? What is the problem when the number connections is too high ? Too much memory comsumption ? or too many sockets opened ? or too many context switching between threads ? To be a little bit specific, how could Oracle Forms application scale to thousand of users without facing this problem ? Shall Oracle RAC applied to this case ? I'm sure the answer to this question should depend on quite a number of factors, like the exact spec of the hardware being used. I'm expecting a rough estimation or some experience from the real world.

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  • How do I execute queries upon DB connection in Rails?

    - by sycobuny
    I have certain initializing functions that I use to set up audit logging on the DB server side (ie, not rails) in PostgreSQL. At least one has to be issued (setting the current user) before inserting data into or updating any of the audited tables, or else the whole query will fail spectacularly. I can easily call these every time before running any save operation in the code, but DRY makes me think I should have the code repeated in as few places as possible, particularly since this diverges greatly from the ideal of database agnosticism. Currently I'm attempting to override ActiveRecord::Base.establish_connection in an initializer to set it up so that the queries are run as soon as I connect automatically, but it doesn't behave as I expect it to. Here is the code in the initializer: class ActiveRecord::Base # extend the class methods, not the instance methods class << self alias :old_establish_connection :establish_connection # hide the default def establish_connection(*args) ret = old_establish_connection(*args) # call the default # set up necessary session variables for audit logging # call these after calling default, to make sure conn is established 1st db = self.class.connection db.execute("SELECT SV.set('current_user', 'test@localhost')") db.execute("SELECT SV.set('audit_notes', NULL)") # end "empty variable" err ret # return the default's original value end end end puts "Loaded custom establish_connection into ActiveRecord::Base" sycobuny:~/rails$ ruby script/server = Booting WEBrick = Rails 2.3.5 application starting on http://0.0.0.0:3000 Loaded custom establish_connection into ActiveRecord::Base This doesn't give me any errors, and unfortunately I can't check what the method looks like internally (I was using ActiveRecord::Base.method(:establish_connection), but apparently that creates a new Method object each time it's called, which is seemingly worthless cause I can't check object_id for any worthwhile information and I also can't reverse the compilation). However, the code never seems to get called, because any attempt to run a save or an update on a database object fails as I predicted earlier. If this isn't a proper way to execute code immediately on connection to the database, then what is?

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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • What alternatives do I have if I want a distributed multi-master database?

    - by Jonas
    I will build a system where I want to reduce single-point-of-failures, and I need a database. Is there any (free) relational database systems that can handle multi-master setups good (i.e where it is easy to add and remove nodes) or is it better to go with a NoSQL-database? As what I have understood, a key-value store will handle this better. What database system do you recommend for a multi-master (cluster) setup?

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  • How to translate this 2 queries from Mysql to Postgresql? :

    - by xRobot
    How can I translate this 2 queries in postgresql ? : CREATE TABLE `example` ( `id` int(10) unsigned NOT NULL auto_increment, `from` varchar(255) NOT NULL default '0', `message` text NOT NULL, `lastactivity` timestamp NULL default '0000-00-00 00:00:00', `read` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `from` (`from`) ) DEFAULT CHARSET=utf8; Query: SELECT * FROM table_1 LEFT OUTER JOIN table_2 ON ( table_1.id = table_2.id ) WHERE (table_1.lastactivity > NOW()-100);

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  • What would be better, (1 database + 4 tables) or (2 databases + 2 tables each) ?

    - by griseldas
    Hi there, I would like to be advised on what would be better (in regards to performance) A) 1 DATABASE with 4 tables or B) 2 DATABASES (same server), each with 2 tables. The tables size and usage are more or less similar, so the 2 tables on Database 1 would be similar usage/size to the 2 tables on database 2 The tables could have +500,000 records and the 2 tables on each database are not related (no join queries etc between them) Thanks in advance for your comments

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  • How can I Create a CMS using php where end user doesn't have to know anything about database. Is that possible

    - by cryptex_vinci
    In genera sense if I create a CMS using php .Where I created and named the database in my localhost. Now if I or my clent upload the CMS in any server how will it work. because there is no database in that server. And in my php code I wrote to create database. Now how can i create a CMS which can automatically create database and tables where client doesn't have to know about anything besides uploading the CMS.

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  • Webcast Replay: Upgrading to Oracle Database 11g with Tom Kyte

    - by john.brust
    On Friday, we caught up with Tom Kyte, Oracle database expert and host of AskTom.oracle.com. Join us to hear what Oracle Database 11g Release 2 means to Tom. Learn how you can make 'change' safe and benefit from new functionality to make better use of your standby databases, capture and replay workloads, tune SQL performance, flashback for rapid recovery from human error, and more. Click to view webcast (and Q&A) replay. We also invite you to visit us our Oracle Database 11g upgrade page on otn.oracle.com.

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  • SQL SERVER – Powershell – Importing CSV File Into Database – Video

    - by pinaldave
    Laerte Junior is my very dear friend and Powershell Expert. On my request he has agreed to share Powershell knowledge with us. Laerte Junior is a SQL Server MVP and, through his technology blog and simple-talk articles, an active member of the Microsoft community in Brasil. He is a skilled Principal Database Architect, Developer, and Administrator, specializing in SQL Server and Powershell Programming with over 8 years of hands-on experience. He holds a degree in Computer Science, has been awarded a number of certifications (including MCDBA), and is an expert in SQL Server 2000 / SQL Server 2005 / SQL Server 2008 technologies. Let us read the blog post in his own words. I was reading an excellent post from my great friend Pinal about loading data from CSV files, SQL SERVER – Importing CSV File Into Database – SQL in Sixty Seconds #018 – Video,   to SQL Server and was honored to write another guest post on SQL Authority about the magic of the PowerShell. The biggest stuff in TechEd NA this year was PowerShell. Fellows, if you still don’t know about it, it is better to run. Remember that The Core Servers to SQL Server are the future and consequently the Shell. You don’t want to be out of this, right? Let’s see some PowerShell Magic now. To start our tour, first we need to download these two functions from Powershell and SQL Server Master Jedi Chad Miller.Out-DataTable and Write-DataTable. Save it in a module and add it in your profile. In my case, the module is called functions.psm1. To have some data to play, I created 10 csv files with the same content. I just put the SQL Server Errorlog into a csv file and created 10 copies of it. #Just create a CSV with data to Import. Using SQLErrorLog [reflection.assembly]::LoadWithPartialName(“Microsoft.SqlServer.Smo”) $ServerInstance=new-object (“Microsoft.SqlServer.Management.Smo.Server“) $Env:Computername $ServerInstance.ReadErrorLog() | export-csv-path“c:\SQLAuthority\ErrorLog.csv”-NoTypeInformation for($Count=1;$Count-le 10;$count++)  {       Copy-Item“c:\SQLAuthority\Errorlog.csv”“c:\SQLAuthority\ErrorLog$($count).csv” } Now in my path c:\sqlauthority, I have 10 csv files : Now it is time to create a table. In my case, the SQL Server is called R2D2 and the Database is SQLServerRepository and the table is CSV_SQLAuthority. CREATE TABLE [dbo].[CSV_SQLAuthority]( [LogDate] [datetime] NULL, [Processinfo] [varchar](20) NULL, [Text] [varchar](MAX) NULL ) Let’s play a little bit. I want to import synchronously all csv files from the path to the table: #Importing synchronously $DataImport=Import-Csv-Path ( Get-ChildItem“c:\SQLAuthority\*.csv”) $DataTable=Out-DataTable-InputObject$DataImport Write-DataTable-ServerInstanceR2D2-DatabaseSQLServerRepository-TableNameCSV_SQLAuthority-Data$DataTable Very cool, right? Let’s do it asynchronously and in background using PowerShell  Jobs: #If you want to do it to all asynchronously Start-job-Name‘ImportingAsynchronously‘ ` -InitializationScript  {IpmoFunctions-Force-DisableNameChecking} ` -ScriptBlock {    ` $DataImport=Import-Csv-Path ( Get-ChildItem“c:\SQLAuthority\*.csv”) $DataTable=Out-DataTable-InputObject$DataImport Write-DataTable   -ServerInstance“R2D2″`                   -Database“SQLServerRepository“`                   -TableName“CSV_SQLAuthority“`                   -Data$DataTable             } Oh, but if I have csv files that are large in size and I want to import each one asynchronously. In this case, this is what should be done: Get-ChildItem“c:\SQLAuthority\*.csv” | % { Start-job-Name“$($_)” ` -InitializationScript  {IpmoFunctions-Force-DisableNameChecking} ` -ScriptBlock { $DataImport=Import-Csv-Path$args[0]                $DataTable=Out-DataTable-InputObject$DataImport                Write-DataTable-ServerInstance“R2D2″`                               -Database“SQLServerRepository“`                               -TableName“CSV_SQLAuthority“`                               -Data$DataTable             } -ArgumentList$_.fullname } How cool is that? Let’s make the funny stuff now. Let’s schedule it on an SQL Server Agent Job. If you are using SQL Server 2012, you can use the PowerShell Job Step. Otherwise you need to use a CMDexec job step calling PowerShell.exe. We will use the second option. First, create a ps1 file called ImportCSV.ps1 with the script above and save it in a path. In my case, it is in c:\temp\automation. Just add the line at the end: Get-ChildItem“c:\SQLAuthority\*.csv” | % { Start-job-Name“$($_)” ` -InitializationScript  {IpmoFunctions-Force-DisableNameChecking} ` -ScriptBlock { $DataImport=Import-Csv-Path$args[0]                $DataTable=Out-DataTable-InputObject$DataImport                Write-DataTable-ServerInstance“R2D2″`                               -Database“SQLServerRepository“`                               -TableName“CSV_SQLAuthority“`                               -Data$DataTable             } -ArgumentList$_.fullname } Get-Job | Wait-Job | Out-Null Remove-Job -State Completed Why? See my post Dooh PowerShell Trick–Running Scripts That has Posh Jobs on a SQL Agent Job Remember, this trick is for  ALL scripts that will use PowerShell Jobs and any kind of schedule tool (SQL Server agent, Windows Schedule) Create a Job Called ImportCSV and a step called Step_ImportCSV and choose CMDexec. Then you just need to schedule or run it. I did a short video (with matching good background music) and you can see it at: That’s it guys. C’mon, join me in the #PowerShellLifeStyle. You will love it. If you want to check what we can do with PowerShell and SQL Server, don’t miss Laerte Junior LiveMeeting on July 18. You can have more information in : LiveMeeting VC PowerShell PASS–Troubleshooting SQL Server With PowerShell–English Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology, Video Tagged: Powershell

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  • A Database and LDAP Ice Breaker Video

    - by mark.wilcox
    I made another GoAnimate video - this time it's about using LDAP for database passwords. Since it's on the free site - I didn't want to violate any terms of agreement - so it doesn't mention Oracle explicitly. But if you wanted to actually do what the animation talks about with Oracle database - you need to configure the Oracle database to use Oracle Enterprise User Security. EUS requires OVD or OID and works with most popular LDAP servers including Active Directory and of course our newest Oracle Directory member - Directory Server Enterprise Edition (aka the former Sun directory). So - if you are looking for a simple way to explain why you might want to use LDAP passwords with your databases or maybe just a slight chuckle on a Friday afternoon have a look at the video: -- Posted via email from Virtual Identity Dialogue

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