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  • google reader like architecture

    - by islam
    dear i want to make architect for application like google reader that save users feeds(rss,atoms) in database what is the best architecture i can do to make something like this ineed to know a good db desgin if i have to save something on files (xml or something) need to archive .etc hope to find some hints

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  • Are soft deletes a good idea?

    - by Khou
    Are soft deletes a good idea or a bad idea? Instead of actually deleting a record in your database, you would just flag it as "IsDeleted" = true, and upon recovery of the record you could just flag it as "False". Is this a good idea?

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  • Working with foreigh keys - cannot insert

    - by Industrial
    Hi everyone! Doing my first tryouts with foreign keys in a mySQL database and are trying to do a insert, that fails for this reason: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails Does this mean that foreign keys restrict INSERTS as well as DELETES and/or UPDATES on each table that is enforced with foreign keys relations? Thanks!

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  • How do Relational Databases Work Under the Hood?

    - by Pierreten
    I've always been interested in how you can throw some SQL at at database, and it nearly instantaneously returns your results in an orderly manner without thinking about it as anything other than a black box. What is really going on? I'm pretty sure it has something to do with how values are laid out regularly in memory, similar to an array; but aside from that, I don't know much else. How is SQL parsed in a manner to facilitate all of this?

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  • django forms- register user script

    - by itsandy
    Hi all, I want to make something like http://www.djangosnippets.org/accounts/register/ using django..the register form. I am new to django. i have made a simple view form using django forms but unable o understand how to connect my form to a database. Im using postgresql. is there an easy way to use some snippet or script to achieve this. Please Help

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  • Meaning of Primary Key to Microsoft SQL Server 2008

    - by usr
    What meaning does the concept of a primary key have to the database engine of SQL Server? I don't mean the clustered/nonclustered index created on the "ID" column, i mean the constraint object "primary key". Does it matter if it exists or not? Alternatives: alter table add primary key clustered alter table create clustered index Does it make a difference?

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • Recommended book for Sql Server query optimisation

    - by Patrick Honorez
    Even if I have made a certification exam on Sql Server Design and implementation , I have no clue about how to trace/debug/optimise performance in Sql Sever. Now the database I built is really business critical, and getting big, so it is time for me to dig into optimisation, specially regarding when/where to add indexes. Can you recommend a good book on this subject ? (smaller is better :) Just in case: I am using Sql Server 2008. Thanks

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  • What's wrong with foreign keys?

    - by kronoz
    I remember hearing Joel mention in the podcast that he'd barely ever used a foreign key (if I remember correctly). However, to me they seem pretty vital to avoid duplication and subsequent data integrity problems throughout your database. Do people have some solid reasons as to why (to avoid a discussion in lines with SO principals)? Edit: "I've yet to have a reason to create a foreign key, so this might be my first reason to actually set up one."

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  • How do I update the members of a MySQL SET Type?

    - by MachinationX
    I have a table of values, with one of the columns being of type SET. If it currently has the members ('a', 'b', 'c', 'd'), how do I add 'e' to the possible values? I realize that using a SET type is a little strange, and I'm unclear why one would use it instead of a foreign key to another table with the values of the set, but I didn't design the database in question, and can't change it that much. Thanks for your help!

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  • methods of joining 2 tables without using JOIN or SELECT more than one distinct table in the query

    - by GB_J
    Is there a way of joining results from 2 tables without using JOIN or SELECT from more than one table? The reason being the database im working with requires queries that only contain SELECT, FROM, and WHERE clauses containing only one distinct table. I do, however, need information from other tables for the project i'm working on. More info: the querier returns the query results in a .csv format, is there something we can manipulate there?

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  • Oracle/SQL table attribute question

    - by UnceRawr
    I have been given a context schema for a database i need to make for my coursework but some of the attributes (column names) contain letters in brackets at the end of them such as: *x_Number (Adm) *x_Number (A) *x_Number (P) The problem is i have no idea what these letters mean! Can anyone help?

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  • Q&A: Oracle's Paul Needham on How to Defend Against Insider Attacks

    - by Troy Kitch
    Source: Database Insider Newsletter: The threat from insider attacks continues to grow. In fact, just since January 1, 2014, insider breaches have been reported by a major consumer bank, a major healthcare organization, and a range of state and local agencies, according to the Privacy Rights Clearinghouse.  We asked Paul Needham, Oracle senior director, product management, to shed light on the nature of these pernicious risks—and how organizations can best defend themselves against the threat from insider risks. Q. First, can you please define the term "insider" in this context? A. According to the CERT Insider Threat Center, a malicious insider is a current or former employee, contractor, or business partner who "has or had authorized access to an organization's network, system, or data and intentionally exceeded or misused that access in a manner that negatively affected the confidentiality, integrity, or availability of the organization's information or information systems."  Q. What has changed with regard to insider risks? A. We are actually seeing the risk of privileged insiders growing. In the latest Independent Oracle Users Group Data Security Survey, the number of organizations that had not taken steps to prevent privileged user access to sensitive information had grown from 37 percent to 42 percent. Additionally, 63 percent of respondents say that insider attacks represent a medium-to-high risk—higher than any other category except human error (by an insider, I might add). Q. What are the dangers of this type of risk? A. Insiders tend to have special insight and access into the kinds of data that are especially sensitive. Breaches can result in long-term legal issues and financial penalties. They can also damage an organization's brand in a way that directly impacts its bottom line. Finally, there is the potential loss of intellectual property, which can have serious long-term consequences because of the loss of market advantage.  Q. How can organizations protect themselves against abuse of privileged access? A. Every organization has privileged users and that will always be the case. The questions are how much access should those users have to application data stored in the database, and how can that default access be controlled? Oracle Database Vault (See image) was designed specifically for this purpose and helps protect application data against unauthorized access.  Oracle Database Vault can be used to block default privileged user access from inside the database, as well as increase security controls on the application itself. Attacks can and do come from inside the organization, and they are just as likely to come from outside as attempts to exploit a privileged account.  Using Oracle Database Vault protection, boundaries can be placed around database schemas, objects, and roles, preventing privileged account access from being exploited by hackers and insiders.  A new Oracle Database Vault capability called privilege analysis identifies privileges and roles used at runtime, which can then be audited or revoked by the security administrators to reduce the attack surface and increase the security of applications overall.  For a more comprehensive look at controlling data access and restricting privileged data in Oracle Database, download Needham's new e-book, Securing Oracle Database 12c: A Technical Primer. 

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  • "[INS-30131] Initial setup required for the execution of installer validations failed." Encountering this error while installing Oracle database 12c. [on hold]

    - by user132992
    I am trying to install Oracle 12c database on my machine running Fedora 20. And I am encountering this problem: "[INS-30131] Initial setup required for the execution of installer validations failed." And when we see the details then it is like this: Cause - Failed to access the temporary location. Action - Ensure that the current user has required permissions to access the temporary location. Additional Information: - Framework setup check failed on all the nodes - Cause: Cause Of Problem Not Available   - Action: User Action Not Available Summary of the failed nodes fedora - Version of exectask could not be retrieved from node "fedora"   - Cause: Cause Of Problem Not Available   - Action: User Action Not Available To eliminate this error I have tried various measures including the change of permission of the tmp folder and restarting the computer but none is working. Plz someone help me out of this. Any kind of help will be appreciated...

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  • NFS (with Kerberos) mount failing due to "Server not found in Kerberos database" error

    - by Kendall Hopkins
    When running: `sudo mount -t nfs4 -o sec=krb5 sol.domain.com:/ /mnt` I get this error on the client: mount.nfs4: access denied by server while mounting sol.domain.com:/ And on the server syslogs UNKNOWN_SERVER: authtime 0, nfs/[email protected] for nfs/ip-#-#-#-#[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for nfs/ip-#-#-#-#[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database UNKNOWN_SERVER: authtime 0, nfs/[email protected] for krbtgt/[email protected], Server not found in Kerberos database Server keytab file: ubuntu@sol:~$ sudo klist -e -k /etc/krb5.keytab Keytab name: WRFILE:/etc/krb5.keytab KVNO Principal ---- -------------------------------------------------------------------------- 7 host/[email protected] (aes256-cts-hmac-sha1-96) 7 host/[email protected] (arcfour-hmac) 7 host/[email protected] (des3-cbc-sha1) 7 host/[email protected] (des-cbc-crc) 9 nfs/[email protected] (aes256-cts-hmac-sha1-96) 9 nfs/[email protected] (arcfour-hmac) 9 nfs/[email protected] (des3-cbc-sha1) 9 nfs/[email protected] (des-cbc-crc) Client keytab file: ubuntu@mercury:~$ sudo klist -e -k /etc/krb5.keytab Keytab name: WRFILE:/etc/krb5.keytab KVNO Principal ---- -------------------------------------------------------------------------- 3 host/[email protected] (aes256-cts-hmac-sha1-96) 3 host/[email protected] (arcfour-hmac) 3 host/[email protected] (des3-cbc-sha1) 3 host/[email protected] (des-cbc-crc) 3 nfs/[email protected] (aes256-cts-hmac-sha1-96) 3 nfs/[email protected] (arcfour-hmac) 3 nfs/[email protected] (des3-cbc-sha1) 3 nfs/[email protected] (des-cbc-crc)

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  • Database which only holds indexes and last X records in memory?

    - by Xeoncross
    I'm looking for a data store that is very memory efficient while still allowing many object changes per second and disregarding ACID compliance for the last X records. I need this database for a server with not much memory and I can make a key-value store, document, or SQL database work. The idea is that indexes/keys are the only thing I need in memory and all the actual values/objects/rows can be saved on disk do to the low read rate (I just want index/key lookup to be fast). I also don't want records constantly being flushed to disk, so I would like the last X number of records to be held in memory so that 100 or so of them can all be written at once. I don't care if I lose the last 10 seconds worth of objects/values. I do care if the database as a whole is in danger of becoming corrupt. Is there a data-store like this?

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  • Migrating master-slave MySQL database servers to 2 new servers, any tips or suggestions?

    - by mmattax
    I'm setting up 2 new database servers that will be replacing a current master-slave setup. All boxes are running / will be running MySQL on RHEL. Our current naming conventions: db1 - master database db2 - slave (using MySQL replication) db01 - new master db02 - new slave We need to get db01 to be the new master with db02 as the new slave. What is the best way to migrate db1 and db2 to db01 and db02? db1 and db2 are running in a production setting and we need to minimize all downtime; db1 has roughly 30GB of data in the database. Any suggestions or tips on how to migrate to our new servers would be much appreciated.

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  • Windows authenticated users have lost access to master (default) database

    - by Rob Nicholson
    Something very strange has occurred on our production SQL database. Users connecting via Windows authentication appear to have lost all access to the master database. By default, all logins have the default database set to master. So when you connect using SQL Server management studio, they get the error: "Cannot open user default database. Login failed error 4064". What's also worrying is that we have a group called "COMPANY - SQL Administrator" which has sysadmin rights and users in this group also get the same error. Worse, they don't appear to be system administrators anymore... If they change their default database to something else, they can connect and then work on the database, it's just the master database that is problematic. I'm not even sure by what mechanism windows authenticated users get access to the master database. Is it something hard coded in or some property that's got changed? Any ideas? Cheers, Rob.

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  • Can I convert my database/script to UTF-8 ?

    - by Mohannad Otaibi
    How can I convert a database to support UTF-8 and convert it's old data from what ever encoding they're in to UTF-8 ? Extra Info: I'm running a server which has many websites on it, and one of them is running WHMCS (php script to manage hosting clients). WHMCS has an iPhone application where i can browse it through iPhone, the problem is that this application will only run if everything in my website is in UTF-8 encoding. I was using windows-1256 as encoding in my script's settings, and i tried changing that in some point of time to UTF-8 for a while then changed it back to windows-1256 so, the data in the database are some inserted using UTF standards and most of them are windows-1256 If someone could clear the picture for me, Do I need to convert every database on the server or just one DB ? what should I change? If i had to do that manually, I'll do it but I need some expert advise.

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  • DBA Command line options

    - by Anthony Shorten
    There are a number of database utilities supplied with the installation of the Oracle Utilities Application Framework based products. These are typically run in interactive mode where the utility prompts you for the values and then executes the required functionality. Did you know that the utilities also have command line options that allow you to run the utility in silent mode as well? You can assess the command line options by specifying the -h option on the command line. Here is an example of the oragensec command line options: oragensec -d <Owner,OwnerPswd,DbName> -u <Database Users> -r <ReadRole,UserRole> -l <logfile> -h where: -d <Owner,OwnerPswd,DbName> Database connect information for the target database. e.g. spladm,spladm,DB200ODB. -u <Database Users> A comma-separated list of database users where synonyms need to be created. e.g. spluser, splread -r <ReadRole,UserRole> Optional. Names of database roles with read and read-write privileges. Default roles are SPL_READ, SPL_USER. e.g. spl_read,spl_user -l <logfile> Optional. Name of the log file. -h Help The command line options allow the DBA to automate the exeucution either via a script or some utility can than execute utilities. This optin can apply to the majority of DBA utilities supplied with the product. Take a look at others.

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  • SQL SERVER – Identify Most Resource Intensive Queries – SQL in Sixty Seconds #029 – Video

    - by pinaldave
    There are a few questions I often get asked. I wonder how interesting is that in our daily life all of us have to often need the same kind of information at the same time. Here is the example of the similar questions: How many user created tables are there in the database? How many non clustered indexes each of the tables in the database have? Is table Heap or has clustered index on it? How many rows each of the tables is contained in the database? I finally wrote down a very quick script (in less than sixty seconds when I originally wrote it) which can answer above questions. I also created a very quick video to explain the results and how to execute the script. Here is the complete script which I have used in the SQL in Sixty Seconds Video. SELECT [schema_name] = s.name, table_name = o.name, MAX(i1.type_desc) ClusteredIndexorHeap, COUNT(i.TYPE) NoOfNonClusteredIndex, p.rows FROM sys.indexes i INNER JOIN sys.objects o ON i.[object_id] = o.[object_id] INNER JOIN sys.schemas s ON o.[schema_id] = s.[schema_id] LEFT JOIN sys.partitions p ON p.OBJECT_ID = o.OBJECT_ID AND p.index_id IN (0,1) LEFT JOIN sys.indexes i1 ON i.OBJECT_ID = i1.OBJECT_ID AND i1.TYPE IN (0,1) WHERE o.TYPE IN ('U') AND i.TYPE = 2 GROUP BY s.name, o.name, p.rows ORDER BY schema_name, table_name Related Tips in SQL in Sixty Seconds: Find Row Count in Table – Find Largest Table in Database Find Row Count in Table – Find Largest Table in Database – T-SQL Identify Numbers of Non Clustered Index on Tables for Entire Database Index Levels, Page Count, Record Count and DMV – sys.dm_db_index_physical_stats Index Levels and Delete Operations – Page Level Observation What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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