Search Results

Search found 30605 results on 1225 pages for 'database abstraction'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 7/1225 | < Previous Page | 3 4 5 6 7 8 9 10 11 12 13 14  | Next Page >

  • Implementation details of database synchronisation API

    - by Daniel
    I want to achieve a database synchronisation between my server database and a client application. The server would run MySQL and the applications may run different database technologies, their implementation isn't important. I have a MySQL database online and web accessible via an API I wrote in PHP (just a detail). My client application ships with a copy of the online data. As time passes my goal is to check for any changes in the online database and make these updates available to the client app via an API call, by sending a date to an API endpoint corresponding to the last date the app was updated, the response would be a JSON filled with all new objects and updated objects, and delete IDs, this makes possible to update the local store appropriately. Essentially I want to do this: http://dbconvert.com/synchronization.php My question is about the implementation details. Would I need to add a column to my database tables with a "last modified" date? Since the client app could be very out of date if it's been offline for a long time, does that also mean I shouldn't delete data from the online database but instead have another column called "delete" set to 1 and a modified date updated appropriately? Would my SQL query simply check for all data with a modified date superior then the date passed into the API request by the client? I feel like there's a lot more to it then having a ton of dates everywhere. And also, worry that I will need to persist a lot of old data in order to ensure that old versions of the client app always have the opportunity to delete parts of their data when they are able to sync.

    Read the article

  • Oracle Database 12c is Generally Available

    - by Thanos
    Oracle Database 12c, a major release of Oracle’s flagship product, is generally available as of 25 June 2013. Oracle Database 12c introduces a breakthrough, new multitenant architecture enabling customers to create multiple, pluggable databases for database consolidation and cloud deployments. Customers will realize greater efficiency and flexibility through innovations such as Oracle Multitenant option and Automatic Data Optimization with Heat Map, for compressing and tiering data at a higher density. These unique advancements, combined with major enhancements in availability, security, and big data support, make Oracle Database 12c the ideal platform for private and public cloud deployments. As of 25/06/2013, the product is available for download on Linux x86-64, Solaris Sparc64 and Solaris (x86-64) via Oracle Technology Network. A news release is planned for July 1st, and an external launch webcast, Plug into the Cloud with Oracle Database 12c, featuring Mark Hurd, Andy Mendelsohn, Tom Kyte and other experts is planned for July 10th. Open here in New Window Everybody can register for the launch webcast here and register to attend global in-person events here. Resources: www.oracle.com/database www.oracle.com/databaseoptions Oracle Partner Network Database Knowledge Zone Open in Google Docs Viewer Open link in new tab Open link in new window Open link in new incognito window Download file Copy link address Edit PDF File on PDFescape.com

    Read the article

  • Enterprise Manager Database Control Configuration - Recovering From Errors Due to CA Expiry on Oracle Database 10.2.0.4 or 10.2.0.5 from 31-Dec-2010 onwards

    - by jayatheertha.rao(at)oracle.com
    Description What is the Issue? In Enterprise Manager Database Control with Oracle Database 10.2.0.4 and 10.2.0.5, the root certificate used to secure communications via the Secure Socket Layer (SSL) protocol will expire on 31-Dec-2010 00:00:00. The certificate expiration will cause errors if you attempt to configure Database Control on or after 31-Dec-2010. Existing Database Control configurations are not affected by this issue. Likelihood of Occurrence What Versions Are Affected? The issue impacts configuration of Database Control with Oracle Database 10.2.0.4 and 10.2.0.5 only. It does not impact database creation or upgrade. The issue does not impact existing Database Control configurations. What Happens During Database Control Configuration Failure? Database Configuration Assistant (DBCA) and Database Upgrade Assistant (DBUA) Errors Database Configuration Assistant (DBCA) and Database Upgrade Assistant (DBUA) will report the following error in the console: Could not complete the Enterprise Manager configuration.Enterprise manager configuration failed due to the following error -Error starting Database Control Enterprise Manager Configuration Assistant (EMCA) Errors Enterprise Manager Configuration Assistant (EMCA) will write errors similar to those below to the emca.log file: CONFIG: Securing Database Control completed successfully .Jan 2, 2011 7:22:47 PM oracle.sysman.emcp.ParamsManager getParamCONFIG: No value was set for the parameter ORACLE_HOSTNAME.Jan 2, 2011 7:22:47 PM oracle.sysman.emcp.util.DBControlUtil startOMSINFO: Starting Database Control (this may take a while) ...Jan 2, 2011 7:22:47 PM oracle.sysman.emcp.util.PlatformInterface addEnvVarToListCONFIG: Value for env var 'ORACLE_HOSTNAME' is '', discarding the sameCONFIG: Returning env array from cacheJan 2, 2011 7:22:47 PM oracle.sysman.emcp.util.PlatformInterface executeCommandCONFIG: Starting execution: /myhost/bin/emctl start dbconsoleJan 2, 2011 7:27:26 PM oracle.sysman.emcp.util.PlatformInterface executeCommandCONFIG: Exit value of 1Jan 2, 2011 7:27:26 PM oracle.sysman.emcp.util.PlatformInterface executeCommandCONFIG: Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.https://myhost:5501/em/console/aboutApplicationStarting Oracle Enterprise Manager 10g Database Control............................................................................................. failed.------------------------------------------------------------------Logs are generated in directory /myhost/sysman/logJan 2, 2011 7:27:26 PM oracle.sysman.emcp.util.PlatformInterface executeCommandWARNING: Error executing /myhost/bin/emctl start dbconsoleJan 2, 2011 7:27:26 PM oracle.sysman.emcp.EMConfig performSEVERE: Error starting Database ControlRefer to the log file at /myhost/dbua/d4/upgrade/emConfig.log for more details.Jan 2, 2011 7:27:26 PM oracle.sysman.emcp.EMConfig performCONFIG: Stack Trace:oracle.sysman.emcp.exception.EMConfigException: Error starting Database Controlat oracle.sysman.emcp.EMDBPostConfig.performUpgrade(EMDBPostConfig.java:763)at oracle.sysman.emcp.EMDBPostConfig.invoke(EMDBPostConfig.java:232)at oracle.sysman.emcp.EMDBPostConfig.invoke(EMDBPostConfig.java:193)at oracle.sysman.emcp.EMConfig.perform(EMConfig.java:184)at oracle.sysman.assistants.util.em.EMConfiguration.run(EMConfiguration.java:436)at oracle.sysman.assistants.util.em.EMConfigStep.executeImpl(EMConfigStep.java:140)at oracle.sysman.assistants.util.step.BasicStep.execute(BasicStep.java:210)at oracle.sysman.assistants.util.step.BasicStep.callStep(BasicStep.java:251)at oracle.sysman.assistants.dbma.backend.EMConfigStep.executeStepImpl(EMConfigStep.java:104)at oracle.sysman.assistants.dbma.backend.SummarizableStep.executeImpl(SummarizableStep.java:175)at oracle.sysman.assistants.util.step.BasicStep.execute(BasicStep.java:210)at oracle.sysman.assistants.util.step.Step.execute(Step.java:140)at oracle.sysman.assistants.util.step.StepContext$ModeRunner.run(StepContext.java:2488)at java.lang.Thread.run(Thread.java:534) The EMCA console will display output similar to the following: aime@myhost09 db_1]$ bin/emca -config dbcontrol db -repos recreate -clusterSTARTED EMCA at Jan 11, 2011 4:11:01 PMEM Configuration Assistant, Version 10.2.0.1.0 ProductionCopyright (c) 2003, 2005, Oracle. All rights reserved.Enter the following information:Database unique name: catestDatabase Control is already configured for the database catestYou have chosen to configure Database Control for managing the database catestThis will remove the existing configuration and the default settings and perform a fresh configurationDo you wish to continue? [yes(Y)/no(N)]: YListener port number: 1521Cluster name: myclusterPassword for SYS user:Password for DBSNMP user:Password for SYSMAN user:Email address for notifications (optional):Outgoing Mail (SMTP) server for notifications (optional):........Jan 11, 2011 4:18:05 PM oracle.sysman.emcp.util.DBControlUtil secureDBConsoleINFO: Securing Database Control (this may take a while) ...Jan 11, 2011 4:19:31 PM oracle.sysman.emcp.util.DBControlUtil startOMSINFO: Starting Database Control (this may take a while) ...Jan 11, 2011 4:28:38 PM oracle.sysman.emcp.EMConfig performSEVERE: Error starting Database ControlRefer to the log file at /myhost/oracle/product/10.2.0/db_1/cfgtoollogs/emca/catest/emca_2011-01-11_04-11-01-PM.log for more details.Could not complete the configuration. Refer to the log file at /myhost/oracle/product/10.2.0/db_1/cfgtoollogs/emca/catest/emca_2011-01-11_04-11-01-PM.log for more details. At the end of the database installation on non-Windows platforms, both Database Control and the Management Agent will be up and running, even though the status of both components will be shown as not running, because EMCTL will be unable to connect to the dbconsole process. In addition, Database Control will fail to connect to the Agent. Note for Windows Platform Only:On Windows, the dbconsole process will be stopped after the failed configuration attempt. Note that the tool used to perform Database Control configuration (DBUA, DBCA or EMCA) will also wait for 15 minutes for Database Control to start, then time out. The output of the "emctl status dbconsole" command incorrectly returns the status of Database Control, as shown below: $ ./emctl status dbconsoleOracle Enterprise Manager 10g Database Control Release 10.2.0.1.0Copyright (c) 1996, 2005 Oracle Corporation. All rights reserved.https://myhost:1158/em/console/aboutApplicationOracle Enterprise Manager 10g is not running. The output of the "emctl status agent" command incorrectly returns the status of the Agent, as shownbelow: $ ./emctl status agentOracle Enterprise Manager 10g Database Control Release 10.2.0.1.0Copyright (c) 1996, 2005 Oracle Corporation. All rights reserved.---------------------------------------------------------------Agent is Not Running   For Solution, refer to Note: 1222603.1 Note: 1217493.1

    Read the article

  • What is "The" book for database design?

    - by FarmBoy
    In programming, there is often a canonical book for a particular topic, like the dragon book for compilers, K&R for C, etc. Is their a book regarding modern database design that simply must be read by anyone that would hope to eventually design databases? I'm not looking for a bunch of recommendations here. The answer I'm looking for is either "Yes, it's [Title, author]." or "No, there are many good books on databases, but no one must-read."

    Read the article

  • Book Review: Pro SQL Server 2008 Relational Database Design and Implementation

    - by Alexander Kuznetsov
    Investing in proper database design is a very efficient way to cut maintenance costs. If we expect a system to last, we need to make sure it has a good solid foundation - high quality database design. Surely we can and sometimes do cut corners and save on database design to get things done faster. Unfortunately, such cutting corners frequently comes back and bites us: we may end up spending a lot of time solving issues caused by poor design. So, solid understanding of relational database design is...(read more)

    Read the article

  • ?Oracle Database Appliance???????????

    - by Norihito Yachita
    ?????????????????????????????·????????Oracle Database Appliance???????????????????????????? ?Oracle Database Appliance????Oracle Linux??????2?????Sun Fire?????·???????????Oracle Database 11g Release 2?????Oracle Real Application Clusters???????????????? ?Oracle Database Appliance????????????????????????????????????????????????????????????????OLTP??????????????·?????????????????????????????????????????????????????????????Oracle Real Application Clusters????????????Automatic Storage Management?????????????????

    Read the article

  • XML flat file vs. relational database backend

    - by donpal
    Most projects now need some form of a database. When someone says database, I usually think relational databases, but I still hear about flat file XML databases. What parameters do you take into consideration when deciding between a "real" database and a flat-file XML database. When should one be used over the other, and under what circumstances should I never consider using a flat file (or vice versa a relational) database?

    Read the article

  • sybase bcp import fails

    - by chromeplatedbanana
    We're trying to export some tables from our production database to our test database using bcp. The bcp export seems to work fine, but the import always fails with a data type error (see below). We tested on our test database exporting the table content to a file, then importing it in again immediately, but that failed too. e.g., bcp TABLENAME out ~/tempfile -S servername -U username generates a file as expected. If we use -c option then the number of lines is as expected. However, bcp TABLENAME in ~/tempfile -S servername -U username fails with CTLIB Message: - L0/0D/S0/N0/0/0: blk_int(): blk_layer: CT library error: Cannot find an equivalent CS_TYPE for this TDS data type 49 blk_init failed. We get this whenever we try to copy into TABLENAME, whether from the production or test table dump file. I don't understand why export and import for the same TABLENAME is generating a data type error. What am I doing wrong here? Thanks

    Read the article

  • SQL 2008 Database tuning advisor won’t start

    - by Andrew Hancox
    For some reason I can't get DTA to connect to my development machine. It connects to a remote DB just fine but when I point it to my dev machine I get an error saying: Failed to initialize MSDB database for tuning (exit code: -1073741819). I'm pretty sure it's not a permissions issue since I've used profiler to capture what it's doing and all of the commands it's run so far look fine and are being run under my account which is associated with the sysadmin role, when I run them in sql management studio they go through fine. I'm pretty convinced that the problem is related to creating the objects in MSDB that are used by DTA but I tried creating these manually (I found scripts on the web) and it just seems to push the problem along the line slightly. I'm going out of my mind - have even tried reinstalling SQL but that's not fixed it. I'm using SQL 2008 with SP1 (10.0.2531) on windows server 2008 (patched up to date). SAVE ME!!!!!

    Read the article

  • MSSQL Replace Database in Live Web App

    - by casoninabox
    I have a web app that is currently live. I had the need to make major modifications to the database and now I need to replace the current one. My dev SQL instance is not the live one. I usually just make a backup of the new DB, blow the old one away and Restore my updated one. But now I have data I need to preserve. Most of the current tables have changed, in that extra columns have been added, all existing columns are still there and unchanged. I have access to Management Studio. What is the right way to do this?

    Read the article

  • How do we greatly optimize our MySQL database (or replace it) when using joins?

    - by jkaz
    Hi there, This is the first time I'm approaching an extremely high-volume situation. This is an ad server based on MySQL. However, the query that is used incorporates a lot of JOINs and is generally just slow. (This is Rails ActiveRecord, btw) sel = Ads.find(:all, :select = '*', :joins = "JOIN campaigns ON ads.campaign_id = campaigns.id JOIN users ON campaigns.user_id = users.id LEFT JOIN countries ON countries.campaign_id = campaigns.id LEFT JOIN keywords ON keywords.campaign_id = campaigns.id", :conditions = [flashstr + "keywords.word = ? AND ads.format = ? AND campaigns.cenabled = 1 AND (countries.country IS NULL OR countries.country = ?) AND ads.enabled = 1 AND campaigns.dailyenabled = 1 AND users.uenabled = 1", kw, format, viewer['country'][0]], :order = order, :limit = limit) My questions: Is there an alternative database like MySQL that has JOIN support, but is much faster? (I know there's Postgre, still evaluating it.) Otherwise, would firing up a MySQL instance, loading a local database into memory and re-loading that every 5 minutes help? Otherwise, is there any way I could switch this entire operation to Redis or Cassandra, and somehow change the JOIN behavior to match the (non-JOIN-able) nature of NoSQL? Thank you!

    Read the article

  • Data won't save to SQL database, getting error "close() was never explicitly called on database"

    - by SnowLeppard
    I have a save button in the activity where the user enters data which does this: String subjectName = etName.getText().toString(); String subjectColour = etColour.getText().toString(); SQLDatabase entrySubject = new SQLDatabase(AddSubject.this); entrySubject.open(); entrySubject.createSubjectEntry(subjectName, subjectColour); entrySubject.close(); Which refers to this SQL database class: package com.***.schooltimetable; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class SQLDatabase { public static final String KEY_SUBJECTS_ROWID = "_id"; public static final String KEY_SUBJECTNAME = "name"; public static final String KEY_COLOUR = "colour"; private static final String DATABASE_NAME = "Database"; private static final String DATABASE_TABLE_SUBJECTS = "tSubjects"; private static final int DATABASE_VERSION = 1; private DbHelper ourHelper; private final Context ourContext; private SQLiteDatabase ourDatabase; private static class DbHelper extends SQLiteOpenHelper { public DbHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); // TODO Auto-generated constructor stub } @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("CREATE TABLE " + DATABASE_TABLE_SUBJECTS + " (" + KEY_SUBJECTS_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_SUBJECTNAME + " TEXT NOT NULL, " + KEY_COLOUR + " TEXT NOT NULL);"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_SUBJECTS); onCreate(db); } } public SQLDatabase(Context c) { ourContext = c; } public SQLDatabase open() throws SQLException { ourHelper = new DbHelper(ourContext); ourDatabase = ourHelper.getWritableDatabase(); return this; } public void close() { ourHelper.close(); } public long createSubjectEntry(String subjectName, String subjectColour) { // TODO Auto-generated method stub ContentValues cv = new ContentValues(); cv.put(KEY_SUBJECTNAME, subjectName); cv.put(KEY_COLOUR, subjectColour); return ourDatabase.insert(DATABASE_TABLE_SUBJECTS, null, cv); } public String[][] getSubjects() { // TODO Auto-generated method stub String[] Columns = new String[] { KEY_SUBJECTNAME, KEY_COLOUR }; Cursor c = ourDatabase.query(DATABASE_TABLE_SUBJECTS, Columns, null, null, null, null, null); String[][] Result = new String[1][]; // int iRow = c.getColumnIndex(KEY_LESSONS_ROWID); int iName = c.getColumnIndex(KEY_SUBJECTNAME); int iColour = c.getColumnIndex(KEY_COLOUR); for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) { Result[0][c.getPosition()] = c.getString(iName); Result[1][c.getPosition()] = c.getString(iColour); Settings.subjectCount = c.getPosition(); TimetableEntry.subjectCount = c.getPosition(); } return Result; } This class has other variables and other variations of the same methods for multiple tables in the database, i've cut out the irrelevant ones. I'm not sure what I need to close and where, I've got the entrySubject.close() in my activity. I used the methods for the database from the NewBoston tutorials. Can anyone see what I've done wrong, or where my problem is? Thanks.

    Read the article

  • SQL SERVER – List of All the Samples Database Available to Download for FREE

    - by Pinal Dave
    It is pretty much very common to have a sample database for any database product. Different companies keep on improving their product and keep on coming up with innovation in their product. To demonstrate the capability of their new enhancements they need the sample database. Microsoft have various sample database available for free download for their SQL Server Product. I have collected them here in a single blog post. Download an AdventureWorks Database The AdventureWorks OLTP database supports standard online transaction processing scenarios for a fictitious bicycle manufacturer (Adventure Works Cycles). Scenarios include Manufacturing, Sales, Purchasing, Product Management, Contact Management, and Human Resources. Coconut Dal Coconut Dal is a lightweight data access layer, for use in projects where the Entity Framework cannot be used or Microsoft’s Enterprise Library Data Block is unsuitable. Anyone who is handwriting ADO.NET should use a library instead and Coconut Dal might be the answer.  DataBooster – Extension to ADO.NET Data Provider The dbParallel DataBooster library is a high-performance extension to ADO.NET Data Provider, includes two aspects: 1) A slimmed down API encapsulation which simplified the most common data access operations (DbConnection -> DbCommand -> DbParameter -> DbDataReader) into a single class DbAccess, to help application with a clean DAL, avoid over-packing and redundant-copy of data transfer. 2) A booster for writing mass data onto database. Base on a rational utilization of database concurrency and a effective utilization of network bandwidth. Tabular AMO 2012 The sample is made of two project parts. The first part is a library of functions to manage tabular models -AMO2Tabular V2-. The second part is a sample to build a tabular model -AdventureWorks Tabular AMO 2012- using the AMO2Tabular library; the created model is similar to the ‘AdventureWorks Tabular Model 2012. SQL Server Analysis Services Product Samples SQL Server Analysis Services provides, a unified and integrated view of all your business data as the foundation for all of your traditional reporting, online analytical processing (OLAP) analysis, Key Performance Indicator (KPI) scorecards, and data mining. Analysis Services Samples for SQL Server 2008 R2 This release is dedicated to the samples that ship for Microsoft SQL Server 2008R2. For many of these samples you will also need to download the AdventureWorks family of databases. SQL Server Reporting Services Product Samples This project contains Reporting Services samples released with Microsoft SQL Server product. These samples are in the following five categories: Application Samples, Extension Samples, Model Samples, Report Samples, and Script Samples. If you are interested in contributing Reporting Services samples, please let us know by posting in the developers’ forum. Reporting Services Samples for SQL Server 2008 R2 This release is dedicated to the samples that ship for Microsoft SQL Server 2008 R2 PCU1. For many of these samples you will also need to download the AdventureWorks family of databases. SQL Server Integration Services Product Samples This project contains Integration Services samples released with Microsoft SQL Server product. These samples are in the following two categories: Package Samples and Programming Samples. If you are interested in contributing Integration Services samples, please let us know by posting in the developers’ forum. Integration Services Samples for SQL Server 2008 R2 This release is dedicated to the samples that ship for Microsoft SQL Server 2008R2. For many of these samples you will also need to download the AdventureWorks family of databases. Windows Azure SQL Reporting Admin Sample The SQLReportingAdmin sample for Windows Azure SQL Reporting demonstrates the usage of SQL Reporting APIs, and manages (add/update/delete) permissions of SQL Reporting users. Windows Azure SQL Reporting ReportViewer-SOAP API usage sample These sample projects demonstrate how to embed a Microsoft ReportViewer control that points to reports hosted on SQL Reporting report servers and how to use SQL Reporting SOAP APIs in your Windows Azure Web application. Enterprise Library 5.0 – Integration Pack for Windows Azure This NuGet package contains a zip file with the source code for the Enterprise Library Integration Pack for Windows Azure.  Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Sample Database

    Read the article

  • New Whitepaper: Advanced Compression 11gR1 Benchmarks with EBS 12

    - by Steven Chan
    In my opinion, if there's any reason to upgrade an E-Business Suite environment to the 11gR1 or 11gR2 database, it's the Advanced Compression database option.  Oracle Advanced Compression was introduced in Oracle Database 11g, and allows you to compress structured data (numbers, characters) as well as unstructured data (documents, spreadsheets, XML and other files).  It provides enhanced compression for database backups and also includes network compression for faster synchronization with standby databases.In other words, the promise of Advanced Compression is that it can make your E-Business Suite database smaller and faster.  But how well does it actually deliver on that promise?Apps 12 + Advanced Compression Benchmarks now availableThree of my colleagues, Uday Moogala, Lester Gutierrez, and Andy Tremayne, have been benchmarking Oracle E-Business Suite Release 12 with Advanced Compression 11gR1.  They've just released a detailed whitepaper with their benchmarking results and recommendations.This whitepaper is available in two locations:Oracle E-Business Suite Release 12.1 with Oracle Database 11g Advanced Compression (Note 1110648.1) (requires My Oracle Support access)Oracle E-Business Suite Release 12.1 with Oracle Database 11g Advanced Compression (Applications Benchmark website, PDF, 500K)

    Read the article

  • how to do database updates in each release

    - by Manoj R
    Our application uses database (mostly Oracle), and database is at the core. Each customer has its own database, with its own copy of application. Now with each new release of our product, we also need to update the database schema. These changes are adding new tables, removing columns, manipulating data etc. How do the people handle this? Are there any standard processes for this? EDIT:- The main issue is the databases are huge with many tables and more of huge amount of data. We provide the scripts and some utilities to manipulate the data. How to handle the failures and false negatives? More of looking for this kind articles. http://thedailywtf.com/Articles/Database-Changes-Done-Right.aspx

    Read the article

  • Amazon SOA: database as a Service

    - by Martin Lee
    There is an interesting interview with Werner Vogels which is partly about how Amazon does Service Oriented Architecture: For us service orientation means encapsulating the data with the business logic that operates on the data, with the only access through a published service interface. No direct database access is allowed from outside the service, and there’s no data sharing among the services. I do not understand that. Why do they need to 'wrap' a database into some layer if it already can be consumed as a service by other service through database adaptors? Does Amazon do that just because they need to expose the database to third parties or because of anything else? Why "no direct database access is allowed"? What are the advantages of such an architectural decision?

    Read the article

  • Which database to use and system/db administration by layman [closed]

    - by blah
    So my friend and I got briliant ;) idea for a business. Since it is not predictable whether it will work out or not, we decided to keep cost as low as possible to start with, in particular not to hire anyone. If it will work out as expected it will generate enough profit to hire professionals in few months. But for the first few months we'll be doing everything by ourselfs. He's a business/finance major, and I'm a software developer, so obviously I have to take care of IT :) It will be a webapp, written in python/django. My questions regarding this project: 1) What database should I choose? I'm experienced with oracle, and have been working with SQL Server for a while, but both of them are too expensive(at least now). It's a developer experience, I've never done any dba stuff. I'm looking for something free(as in beer). Looks like MySql or PostgreSQL are most popular in this sector. I would appreciate any comments on which db to choose. I'm open to any suggestions(it doesn't have to be MySql or Postgre). Here's what I know about data: It will be almost dates and numbers, a little bit of text. Searched mainly by dates. Data will almost never be updated, mostly inserted and browsed. From 30k to 300k new records/month. 2) Servers. My idea is to rent two dedicated servers. During normal operation one would be a web server(debian/apache), other would be a db server(debian/?). My recovery plan is to install everything on both, and in case of trouble with one of machines just run everything on the other one. Does it even makes sense? Any other tips appreciated. Thanks.

    Read the article

  • When should we use weak entities when modelling a database?

    - by Songo
    This is basically a question about what are weak entities? When should we use them? How should they be modeled? What is the main difference between normal entities and weak entities? Does weak entities correspond to value objects when doing Domain Driven Design? To help keep the question on topic here is an example taken from Wikipedia that people can use to answer these question: In this example OrderItem was modeled as a weak entity, but I can't understand why it can't be modeled as a normal entity. Another question is what if I want to track the order history (i.e. the changes in it status) would that be a normal or weak entity?

    Read the article

  • Best C# database communication technique

    - by user65439
    A few days ago I read a reply to a question where people said that the days of writing queries within your c# code are long gone. I'm not sure what the specific person meant with the comment but it got me thinking. At the company I'm currently working at we maintain an assembly containing all the queries to the database (let's call it Queries), this assembly is reference by a QueryService (Retrieve the correct queries) assembly which in turn is referenced by a UnitOfWork assembly (The database connector classes, we have different connector classes for SQL, MySQL etc.). We use these three assemblies to perform operations on our database and all queries/commands are written in our C# code. Is there a better way to communicate with the database and is there a better way to communicate with different database types?

    Read the article

  • Single database, multiple system dependency

    - by davenewza
    Consider an environment where we have a single, core database, with many separate systems using this one database. This leads to all of these systems have a common dependency, which ultimately introduces coupling between them. This means that we cannot always evolve systems independently of each other. Structural changes to the database (even if only intended for one, particular system), requires a full sweep test of ALL systems, and may require that other systems be 'patched' and subsequently released. This is especially tricky when you want to have separate teams working on different projects. What is a good 'pattern' to help in avoiding such coupling? I would imagine that a database should be exclusively depended on by one system. If other systems require data for whatever reason, they should request such from an API service of some kind. A drawback of this approach which comes to mind is performance: routing data between high-throughput systems through service calls is much slower than through a database connection.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 3 4 5 6 7 8 9 10 11 12 13 14  | Next Page >