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  • archiving strategies and limitations of data in a table

    - by Samuel
    Environment: Jboss, Mysql, JPA, Hibernate Our web application will be catering to a large amount of users (~ 1,000,000) and there are a lots of child table where user specific data are stored (e.g. personal, health, forum contributions ...). What would be the best practice to archive user & user specific information. [a] Would it be wise to move the archived user & user specific information to their respective tables within the same database (e.g. user_archive, user_forum_comments_archive ...) OR [b] Would you just mark the database entries with a flag in the original table(s) and just query only non archived entries. We have a unique constraint on User.loginid, how do you handle this requirement if the users are archived via 1-[a] (i.e if a user with loginid 'samuel' gets moved into the archive table and if a new user gets added with the same name in the original table, how would you prevent this. What would be the best strategy to address the unique key constraints. We have a requirement to selectively archive records and bring it back if necessary, will you rely on database tools are would you handle this via your persistence APIs exposed by the JPA entity model.

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  • Are bad data issues that common?

    - by Water Cooler v2
    I've worked for clients that had a large number of distinct, small to mid-sized projects, each interacting with each other via properly defined interfaces to share data, but not reading and writing to the same database. Each had their own separate database, their own cache, their own file servers/system that they had dedicated access to, and so they never caused any problems. One of these clients is a mobile content vendor, so they're lucky in a way that they do not have to face the same problems that everyday business applications do. They can create all those separate compartments where their components happily live in isolation of the others. However, for many business applications, this is not possible. I've worked with a few clients, one of whose applications I am doing the production support for, where there are "bad data issues" on an hourly basis. Yeah, it's that crazy. Some data records from one of the instances (lower than production, of course) would have been run a couple of weeks ago, and caused some other user's data to get corrupted. And then, a data script will have to be written to fix this issue. And I've seen this happening so much with this client that I have to ask. I've seen this happening at a moderate rate with other clients, but this one just seems to be out of order. If you're working with business applications that share a large amount of data by reading and writing to/from the same database, are "bad data issues" that common in your environment?

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  • How To - Guide to Importing Data from a MySQL Database to Excel using MySQL for Excel

    - by Javier Treviño
    Fetching data from a database to then get it into an Excel spreadsheet to do analysis, reporting, transforming, sharing, etc. is a very common task among users. There are several ways to extract data from a MySQL database to then import it to Excel; for example you can use the MySQL Connector/ODBC to configure an ODBC connection to a MySQL database, then in Excel use the Data Connection Wizard to select the database and table from which you want to extract data from, then specify what worksheet you want to put the data into.  Another way is to somehow dump a comma delimited text file with the data from a MySQL table (using the MySQL Command Line Client, MySQL Workbench, etc.) to then in Excel open the file using the Text Import Wizard to attempt to correctly split the data in columns. These methods are fine, but involve some degree of technical knowledge to make the magic happen and involve repeating several steps each time data needs to be imported from a MySQL table to an Excel spreadsheet. So, can this be done in an easier and faster way? With MySQL for Excel you can. MySQL for Excel features an Import MySQL Data action where you can import data from a MySQL Table, View or Stored Procedure literally with a few clicks within Excel.  Following is a quick guide describing how to import data using MySQL for Excel. This guide assumes you already have a working MySQL Server instance, Microsoft Office Excel 2007 or 2010 and MySQL for Excel installed. 1. Opening MySQL for Excel Being an Excel Add-In, MySQL for Excel is opened from within Excel, so to use it open Excel, go to the Data tab located in the Ribbon and click MySQL for Excel at the far right of the Ribbon. 2. Creating a MySQL Connection (may be optional) If you have MySQL Workbench installed you will automatically see the same connections that you can see in MySQL Workbench, so you can use any of those and there may be no need to create a new connection. If you want to create a new connection (which normally you will do only once), in the Welcome Panel click New Connection, which opens the Setup New Connection dialog. Here you only need to give your new connection a distinctive Connection Name, specify the Hostname (or IP address) where the MySQL Server instance is running on (if different than localhost), the Port to connect to and the Username for the login. If you wish to test if your setup is good to go, click Test Connection and an information dialog will pop-up stating if the connection is successful or errors were found. 3.Opening a connection to a MySQL Server To open a pre-configured connection to a MySQL Server you just need to double-click it, so the Connection Password dialog is displayed where you enter the password for the login. 4. Selecting a MySQL Schema After opening a connection to a MySQL Server, the Schema Selection Panel is shown, where you can select the Schema that contains the Tables, Views and Stored Procedures you want to work with. To do so, you just need to either double-click the desired Schema or select it and click Next >. 5. Importing data… All previous steps were really the basic minimum needed to drill-down to the DB Object Selection Panel  where you can see the Database Objects (grouped by type: Tables, Views and Procedures in that order) that you want to perform actions against; in the case of this guide, the action of importing data from them. a. From a MySQL Table To import from a Table you just need to select it from the list of Database Objects’ Tables group, after selecting it you will note actions below the list become available; then click Import MySQL Data. The Import Data dialog is displayed; you can see some basic information here like the name of the Excel worksheet the data will be imported to (in the window title), the Table Name, the total Row Count and a 10 row preview of the data meant for the user to see the columns that the table contains and to provide a way to select which columns to import. The Import Data dialog is designed with defaults in place so all data is imported (all rows and all columns) by just clicking Import; this is important to minimize the number of clicks needed to get the job done. After the import is performed you will have the data in the Excel worksheet formatted automatically. If you need to override the defaults in the Import Data dialog to change the columns selected for import or to change the number of imported rows you can easily do so before clicking Import. In the screenshot below the defaults are overridden to import only the first 3 columns and rows 10 – 60 (Limit to 50 Rows and Start with Row 10). If the number of rows to be imported exceeds the maximum number of rows Excel can hold in its worksheet, a warning will be displayed in the dialog, meaning the imported number of rows will be limited by that maximum number (65,535 rows if the worksheet is in Compatibility Mode).  In the screenshot below you can see the Table contains 80,559 rows, but only 65,534 rows will be imported since the first row is used for the column names if the Include Column Names as Headers checkbox is checked. b. From a MySQL View Similar to the way of importing from a Table, to import from a View you just need to select it from the list of Database Objects’ Views group, then click Import MySQL Data. The Import Data dialog is displayed; identically to the way everything looks when importing from a table, the dialog displays the View Name, the total Row Count and the data preview grid. Since Views are really a filtered way to display data from Tables, it is actually as if we are extracting data from a Table; so the Import Data dialog is actually identical for those 2 Database Objects. After the import is performed, the data in the Excel spreadsheet looks like the following screenshot. Note that you can override the defaults in the Import Data dialog in the same way described above for importing data from Tables. Also the Compatibility Mode warning will be displayed if data exceeds the maximum number of rows explained before. c. From a MySQL Procedure Too import from a Procedure you just need to select it from the list of Database Objects’ Procedures group (note you can see Procedures here but not Functions since these return a single value, so by design they are filtered out). After the selection is made, click Import MySQL Data. The Import Data dialog is displayed, but this time you can see it looks different to the one used for Tables and Views.  Given the nature of Store Procedures, they require first that values are supplied for its Parameters and also Procedures can return multiple Result Sets; so the Import Data dialog shows the Procedure Name and the Procedure Parameters in a grid where their values are input. After you supply the Parameter Values click Call. After calling the Procedure, the Result Sets returned by it are displayed at the bottom of the dialog; output parameters and the return value of the Procedure are appended as the last Result Set of the group. You can see each Result Set is displayed as a tab so you can see a preview of the returned data.  You can specify if you want to import the Selected Result Set (default), All Result Sets – Arranged Horizontally or All Result Sets – Arranged Vertically using the Import drop-down list; then click Import. After the import is performed, the data in the Excel spreadsheet looks like the following screenshot.  Note in this example all Result Sets were imported and arranged vertically. As you can see using MySQL for Excel importing data from a MySQL database becomes an easy task that requires very little technical knowledge, so it can be done by any type of user. Hope you enjoyed this guide! Remember that your feedback is very important for us, so drop us a message: MySQL on Windows (this) Blog - https://blogs.oracle.com/MySqlOnWindows/ Forum - http://forums.mysql.com/list.php?172 Facebook - http://www.facebook.com/mysql Cheers!

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  • FOUR questions to ask if you are implementing DATABASE-AS-A-SERVICE

    - by Sudip Datta
    During my ongoing tenure at Oracle, I have met all types of DBAs. Happy DBAs, unhappy DBAs, proud DBAs, risk-loving DBAs, cautious DBAs. These days, as Database-as-a-Service (DBaaS) becomes more mainstream, I find some complacent DBAs who are basking in their achievement of having implemented DBaaS. Some others, however, are not that happy. They grudgingly complain that they did not have much of a say in the implementation, they simply had to follow what their cloud architects (mostly infrastructure admins) offered them. In most cases it would be a database wrapped inside a VM that would be labeled as “Database as a Service”. In other cases, it would be existing brute-force automation simply exposed in a portal. As much as I think that there is more to DBaaS than those approaches and often get tempted to propose Enterprise Manager 12c, I try to be objective. Neither do I want to dampen the spirit of the happy ones, nor do I want to stoke the pain of the unhappy ones. As I mentioned in my previous post, I don’t deny vanilla automation could be useful. I like virtualization too for what it has helped us accomplish in terms of resource management, but we need to scrutinize its merit on a case-by-case basis and apply it meaningfully. For DBAs who either claim to have implemented DBaaS or are planning to do so, I simply want to provide four key questions to ponder about: 1. Does it make life easier for your end users? Database-as-a-Service can have several types of end users. Junior DBAs, QA Engineers, Developers- each having their own skillset. The objective of DBaaS is to make their life simple, so that they can focus on their core responsibilities without having to worry about additional stuff. For example, if you are a Developer using Oracle Application Express (APEX), you want to deal with schema, objects and PL/SQL code and not with datafiles or listener configuration. If you are a QA Engineer needing database copies for functional testing, you do not want to deal with underlying operating system patching and compliance issues. The question to ask, therefore, is, whether DBaaS makes life easier for those users. It is often convenient to give them VM shells to deal with a la Amazon EC2 IaaS, but is that what they really want? Is it a productive use of a developer's time if he needs to apply RPM errata to his Linux operating system. Asking him to keep the underlying operating system current is like making a guest responsible for a restaurant's decor. 2. Does it make life easier for your administrators? Cloud, in general, is supposed to free administrators from attending to mundane tasks like provisioning services for every single end user request. It is supposed to enable a readily consumable platform and enforce standardization in the process. For example, if a Service Catalog exposes DBaaS of specific database versions and configurations, it, by its very nature, enforces certain discipline and standardization within the IT environment. What if, instead of specific database configurations, cloud allowed each end user to create databases of their liking resulting in hundreds of version and patch levels and thousands of individual databases. Therefore the right question to ask is whether the unwanted consequence of DBaaS is OS and database sprawl. And if so, who is responsible for tracking them, backing them up, administering them? Studies have shown that these administrative overheads increase exponentially with new targets, and it could result in a management nightmare. That leads us to our next question. 3. Does it satisfy your Security Officers and Compliance Auditors? Compliance Auditors need to know who did what and when. They also want the cloud platform to be secure, so that end users have little freedom in tampering with it. Dealing with VM sprawl is not the easiest of challenges, let alone dealing with them as they keep getting reconfigured and moved around. This leads to the proverbial needle in the haystack problem, and all it needs is one needle to cause a serious compliance issue in the enterprise. Bottomline is, flexibility and agility should not come at the expense of compliance and it is very important to get the balance right. Can we have security and isolation without creating compliance challenges? Instead of a ‘one size fits all approach’ i.e. OS level isolation, can we think smartly about database isolation or schema based isolation? This is where the appropriate resource modeling needs to be applied. The usual systems management vendors out there with heterogeneous common-denominator approach have compromised on these semantics. If you follow Enterprise Manager’s DBaaS solution, you will see that we have considered different models, not precluding virtualization, for different customer use cases. The judgment to use virtual assemblies versus databases on physical RAC versus Schema-as-a-Service in a single database, should be governed by the need of the applications and not by putting compliance considerations in the backburner. 4. Does it satisfy your CIO? Finally, does it satisfy your higher ups? As the sponsor of cloud initiative, the CIO is expected to lead an IT transformation project, not merely a run-of-the-mill IT operations. Simply virtualizing server resources and delivering them through self-service is a good start, but hardly transformational. CIOs may appreciate the instant benefit from server consolidation, but studies have revealed that the ROI from consolidation would flatten out at 20-25%. The question would be: what next? As we go higher up in the stack, the need to virtualize, segregate and optimize shifts to those layers that are more palpable to the business users. As Sushil Kumar noted in his blog post, " the most important thing to note here is the enterprise private cloud is not just an IT project, rather it is a business initiative to create an IT setup that is more aligned with the needs of today's dynamic and highly competitive business environment." Business users could not care less about infrastructure consolidation or virtualization - they care about business agility and service level assurance. Last but not the least, lot of CIOs get miffed if we ask them to throw away their existing hardware investments for implementing DBaaS. In Oracle, we always emphasize on freedom of choosing a platform; hence Enterprise Manager’s DBaaS solution is platform neutral. It can work on any Operating System (that the agent is certified on) Oracle’s hardware as well as 3rd party hardware. As a parting note, I urge you to remember these 4 questions. Remember that your satisfaction as an implementer lies in the satisfaction of others.

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  • Export and import a PostgreSQL database with a different name?

    - by J. Pablo Fernández
    Is there a way to export a PostgreSQL database and later import it with another name? I'm using PostgreSQL with Rails and I often export the data from production, where the database is called blah_production and import it on development or staging with names blah_development and blah_staging. On MySQL this is trivial as the export doesn't have the database anywhere (except a comment maybe), but on PostgreSQL it seems to be impossible. Is it impossible? I've seen out there some people using sed scripts to modify the dump. I'd like to avoid that solution but if there are no alternative I'll take it. Has anybody wrote a script to alter the dump's database name ensure no data is ever altered?

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  • What are the pros of switching DNS names with a database server hardware upgrade?

    - by wilbbe01
    When we upgrade to new hardware at work we usually increment a number in the DNS name. For example. We have a server called database-2, that is slated to become database-3 in the coming days. I haven't been able to find a good reason why this is good behavior. To me the work of trying to catch all end user machines, as well as all servers dependent on the database server is far riskier than simply moving the database and ip/name with it to the new hardware. A little over a year ago we spent several months of requests coming in, as infrequent users began using software that needed to be updated to point to a new DNS name. I am struggling to find answers as to why this is a good practice. So the question. Why is using DNS names as a "server hardware version identifier" a good idea? What am I overlooking? Thanks much.

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  • Gathering statistics for an Oracle WebCenter Content Database

    - by Nicolas Montoya
    Have you ever heard: "My Oracle WebCenter Content instance is running slow. I checked the memory and CPU usage of the application server and it has plenty of resources. What could be going wrong?An Oracle WebCenter Content instance runs on an application server and relies on a database server on the back end. If your application server tier is running fine, chances are that your database server tier may host the root of the problem. While many things could cause performance problems, on active Enterprise Content Management systems, keeping database statistics updated is extremely important.The Oracle Database have a set of built-in optimizer utilities that can help make database queries more efficient. It is strongly recommended to update or re-create the statistics about the physical characteristics of a table and the associated indexes in order to maximize the efficiency of optimizers. These physical characteristics include: Number of records Number of pages Average record length The frequency with which you need to update statistics depends on how quickly the data is changing. Typically, statistics should be updated when the number of new items since the last update is greater than ten percent of the number of items when the statistics were last updated. If a large amount of documents are being added or removed from the system, the a post step should be added to gather statistics upon completion of this massive data change. In some cases, you may need to collect statistics in the middle of the data processing to expedite its execution. These proceses include but are not limited to: data migration, bootstrapping of a new system, records management disposition processing (typically at the end of the calendar year), etc. A DOCUMENTS table with a ten million rows will often generate a very different plan than a table with just a thousand.A quick check of the statistics for the WebCenter Content (WCC) Database could be performed via the below query:SELECT OWNER, TABLE_NAME, NUM_ROWS, BLOCKS, AVG_ROW_LEN,TO_CHAR(LAST_ANALYZED, 'MM/DD/YYYY HH24:MI:SS')FROM DBA_TABLESWHERE TABLE_NAME='DOCUMENTS';OWNER                          TABLE_NAME                       NUM_ROWS------------------------------ ------------------------------ ----------    BLOCKS AVG_ROW_LEN TO_CHAR(LAST_ANALYZ---------- ----------- -------------------ATEAM_OCS                      DOCUMENTS                            4172        46          61 04/06/2012 11:17:51This output will return not only the date when the WCC table DOCUMENTS was last analyzed, but also it will return the <DATABASE SCHEMA OWNER> for this table in the form of <PREFIX>_OCS.This database username could later on be used to check on other objects owned by the WCC <DATABASE SCHEMA OWNER> as shown below:SELECT OWNER, TABLE_NAME, NUM_ROWS, BLOCKS, AVG_ROW_LEN,TO_CHAR(LAST_ANALYZED, 'MM/DD/YYYY HH24:MI:SS')FROM DBA_TABLESWHERE OWNER='ATEAM_OCS'ORDER BY NUM_ROWS ASC;...OWNER                          TABLE_NAME                       NUM_ROWS------------------------------ ------------------------------ ----------    BLOCKS AVG_ROW_LEN TO_CHAR(LAST_ANALYZ---------- ----------- -------------------ATEAM_OCS                      REVISIONS                            2051        46         141 04/09/2012 22:00:22ATEAM_OCS                      DOCUMENTS                            4172        46          61 04/06/2012 11:17:51ATEAM_OCS                      ARCHIVEHISTORY                       4908       244         218 04/06/2012 11:17:49OWNER                          TABLE_NAME                       NUM_ROWS------------------------------ ------------------------------ ----------    BLOCKS AVG_ROW_LEN TO_CHAR(LAST_ANALYZ---------- ----------- -------------------ATEAM_OCS                      DOCUMENTHISTORY                      5865       110          72 04/06/2012 11:17:50ATEAM_OCS                      SCHEDULEDJOBSHISTORY                10131       244         131 04/06/2012 11:17:54ATEAM_OCS                      SCTACCESSLOG                        10204       496         268 04/06/2012 11:17:54...The Oracle Database allows to collect statistics of many different kinds as an aid to improving performance. The DBMS_STATS package is concerned with optimizer statistics only. The database sets automatic statistics collection of this kind on by default, DBMS_STATS package is intended for only specialized cases.The following subprograms gather certain classes of optimizer statistics:GATHER_DATABASE_STATS Procedures GATHER_DICTIONARY_STATS Procedure GATHER_FIXED_OBJECTS_STATS Procedure GATHER_INDEX_STATS Procedure GATHER_SCHEMA_STATS Procedures GATHER_SYSTEM_STATS Procedure GATHER_TABLE_STATS ProcedureThe DBMS_STATS.GATHER_SCHEMA_STATS PL/SQL Procedure gathers statistics for all objects in a schema.DBMS_STATS.GATHER_SCHEMA_STATS (    ownname          VARCHAR2,    estimate_percent NUMBER   DEFAULT to_estimate_percent_type                                                 (get_param('ESTIMATE_PERCENT')),    block_sample     BOOLEAN  DEFAULT FALSE,    method_opt       VARCHAR2 DEFAULT get_param('METHOD_OPT'),   degree           NUMBER   DEFAULT to_degree_type(get_param('DEGREE')),    granularity      VARCHAR2 DEFAULT GET_PARAM('GRANULARITY'),    cascade          BOOLEAN  DEFAULT to_cascade_type(get_param('CASCADE')),    stattab          VARCHAR2 DEFAULT NULL,    statid           VARCHAR2 DEFAULT NULL,    options          VARCHAR2 DEFAULT 'GATHER',    objlist          OUT      ObjectTab,   statown          VARCHAR2 DEFAULT NULL,    no_invalidate    BOOLEAN  DEFAULT to_no_invalidate_type (                                     get_param('NO_INVALIDATE')),  force             BOOLEAN DEFAULT FALSE);There are several values for the OPTIONS parameter that we need to know about: GATHER reanalyzes the whole schema     GATHER EMPTY only analyzes tables that have no existing statistics GATHER STALE only reanalyzes tables with more than 10 percent modifications (inserts, updates,   deletes) GATHER AUTO will reanalyze objects that currently have no statistics and objects with stale statistics. Using GATHER AUTO is like combining GATHER STALE and GATHER EMPTY. Example:exec dbms_stats.gather_schema_stats( -   ownname          => '<PREFIX>_OCS', -   options          => 'GATHER AUTO' -);

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  • Oracle?????????????~????????????????????

    - by Yusuke.Yamamoto
    RDBMS ???????·????????????????????????????????????????????????????????????????????????? ????????Oracle ?????????????????????????????????? Oracle Database ???????????????????????????????? Oracle????????????? ??????????????????????????????????? ?????????????????????????????? ????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????? Oracle Database ?? Compile Time ???????? ?????????SQL??????Oracle Database ????????????????????????????????????????????????????????????????? ????????????????????????????????????????????? RDBMS ???????????????????? ???????????????? Oracle Database ????????????????????????? ?????????????Oracle Database ????????????????????????????RDBMS ???????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????? ?????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????? Oracle Database ???????????????????????? Oracle Database ????????????????????? "Oracle ????????" ?????????? Sustaining Engineering?? ?(??? ???) ???????????????? Sustaining Engineering ????????????????????????Oracle Database ???????????????????????? Oracle????????????????????????! Oracle?????????????

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  • Database Migration Scripts: Getting from place A to place B

    - by Phil Factor
    We’ll be looking at a typical database ‘migration’ script which uses an unusual technique to migrate existing ‘de-normalised’ data into a more correct form. So, the book-distribution business that uses the PUBS database has gradually grown organically, and has slipped into ‘de-normalisation’ habits. What’s this? A new column with a list of tags or ‘types’ assigned to books. Because books aren’t really in just one category, someone has ‘cured’ the mismatch between the database and the business requirements. This is fine, but it is now proving difficult for their new website that allows searches by tags. Any request for history book really has to look in the entire list of associated tags rather than the ‘Type’ field that only keeps the primary tag. We have other problems. The TypleList column has duplicates in there which will be affecting the reporting, and there is the danger of mis-spellings getting there. The reporting system can’t be persuaded to do reports based on the tags and the Database developers are complaining about the unCoddly things going on in their database. In your version of PUBS, this extra column doesn’t exist, so we’ve added it and put in 10,000 titles using SQL Data Generator. /* So how do we refactor this database? firstly, we create a table of all the tags. */IF  OBJECT_ID('TagName') IS NULL OR OBJECT_ID('TagTitle') IS NULL  BEGIN  CREATE TABLE  TagName (TagName_ID INT IDENTITY(1,1) PRIMARY KEY ,     Tag VARCHAR(20) NOT NULL UNIQUE)  /* ...and we insert into it all the tags from the list (remembering to take out any leading spaces */  INSERT INTO TagName (Tag)     SELECT DISTINCT LTRIM(x.y.value('.', 'Varchar(80)')) AS [Tag]     FROM     (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )  /* we can then use this table to provide a table that relates tags to articles */  CREATE TABLE TagTitle   (TagTitle_ID INT IDENTITY(1, 1),   [title_id] [dbo].[tid] NOT NULL REFERENCES titles (Title_ID),   TagName_ID INT NOT NULL REFERENCES TagName (Tagname_ID)   CONSTRAINT [PK_TagTitle]       PRIMARY KEY CLUSTERED ([title_id] ASC, TagName_ID)       ON [PRIMARY])        CREATE NONCLUSTERED INDEX idxTagName_ID  ON  TagTitle (TagName_ID)  INCLUDE (TagTitle_ID,title_id)        /* ...and it is easy to fill this with the tags for each title ... */        INSERT INTO TagTitle (Title_ID, TagName_ID)    SELECT DISTINCT Title_ID, TagName_ID      FROM        (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )    INNER JOIN TagName ON TagName.Tag=LTRIM(x.y.value('.', 'Varchar(80)'))    END    /* That's all there was to it. Now we can select all titles that have the military tag, just to try things out */SELECT Title FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE tagname.tag='Military'/* and see the top ten most popular tags for titles */SELECT Tag, COUNT(*) FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  GROUP BY Tag ORDER BY COUNT(*) DESC/* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID So we’ve refactored our PUBS database without pain. We’ve even put in a check to prevent it being re-run once the new tables are created. Here is the diagram of the new tag relationship We’ve done both the DDL to create the tables and their associated components, and the DML to put the data in them. I could have also included the script to remove the de-normalised TypeList column, but I’d do a whole lot of tests first before doing that. Yes, I’ve left out the assertion tests too, which should check the edge cases and make sure the result is what you’d expect. One thing I can’t quite figure out is how to deal with an ordered list using this simple XML-based technique. We can ensure that, if we have to produce a list of tags, we can get the primary ‘type’ to be first in the list, but what if the entire order is significant? Thank goodness it isn’t in this case. If it were, we might have to revisit a string-splitter function that returns the ordinal position of each component in the sequence. You’ll see immediately that we can create a synchronisation script for deployment from a comparison tool such as SQL Compare, to change the schema (DDL). On the other hand, no tool could do the DML to stuff the data into the new table, since there is no way that any tool will be able to work out where the data should go. We used some pretty hairy code to deal with a slightly untypical problem. We would have to do this migration by hand, and it has to go into source control as a batch. If most of your database changes are to be deployed by an automated process, then there must be a way of over-riding this part of the data synchronisation process to do this part of the process taking the part of the script that fills the tables, Checking that the tables have not already been filled, and executing it as part of the transaction. Of course, you might prefer the approach I’ve taken with the script of creating the tables in the same batch as the data conversion process, and then using the presence of the tables to prevent the script from being re-run. The problem with scripting a refactoring change to a database is that it has to work both ways. If we install the new system and then have to rollback the changes, several books may have been added, or had their tags changed, in the meantime. Yes, you have to script any rollback! These have to be mercilessly tested, and put in source control just in case of the rollback of a deployment after it has been in place for any length of time. I’ve shown you how to do this with the part of the script .. /* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID …which would be turned into an UPDATE … FROM script. UPDATE titles SET  typelist= ThisTaglistFROM     (SELECT title_ID, title, STUFF(    (SELECT ','+tagname.tag FROM titles thisTitle      INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID      INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID    WHERE ThisTitle.title_id=titles.title_ID    ORDER BY CASE WHEN tagname.tag=titles.[type] THEN 1 ELSE 0  END DESC    FOR XML PATH(''), TYPE).value('.', 'varchar(max)')    ,1,1,'')  AS ThisTagList  FROM titles)fINNER JOIN Titles ON f.title_ID=Titles.title_ID You’ll notice that it isn’t quite a round trip because the tags are in a different order, though we’ve managed to make sure that the primary tag is the first one as originally. So, we’ve improved the database for the poor book distributors using PUBS. It is not a major deal but you’ve got to be prepared to provide a migration script that will go both forwards and backwards. Ideally, database refactoring scripts should be able to go from any version to any other. Schema synchronization scripts can do this pretty easily, but no data synchronisation scripts can deal with serious refactoring jobs without the developers being able to specify how to deal with cases like this.

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  • Dissertation about website and database security - in need of some pointers

    - by ClarkeyBoy
    Hi, I am on my dissertation in my final year at university at the moment. One of the areas I need to research is security - for both websites and for databases. I currently have sections on the following: Website Form security - such as data validation. This section is more about preventing errors made by legitimate users as much as possible rather than stopping hackers, for example comparing a field to a regular expression and giving them meaningful feedback on any errors which did occur so as to stop it happening again. Constraints. For example if a value must be true or false then use a checkbox. If it is likely to be one of several values then use a dropdown or a set of radio boxes, and so on. If the value is unpredictable then use regular expressions to limit what characters they are allowed to enter, and to restrict the length of the string, and sometimes to limit the format (such as for dates / times, post codes and so on). Sometimes you can limit permissions to the form. This is on the occasion that you know exactly who (whether it be peoples names or a group of people - such as administrators or employees) is going to need access to the form. Restricting permissions will stop members of the public from being able to access the form. Symbols or strings which could be used maliciously or cause the website to act incorrectly (such as the script tag) should be filtered out or html encoded. Captcha images can be used to prevent automated systems from filling in and submitting the form. There are some hacks for file uploads - such as using double extensions - which can allow hackers to upload malicious files. Databases (this is nowhere near done yet but the sections I have planned are listed below) SQL statements vs stored procedures Throwing an error when one of the variables contains particular characters or groups of characters (I cant remember what characters they are, but I have seen a message thrown back at me before where I have tried to enter html or something into a text area). SQL Injection - and ways around it, with some examples. Does anyone have any hints and tips on where I could go for some decent, reliable information either about these areas or about other areas of security that I could cover? Thanks in advance. Regards, Richard PS I am a complete newbie when it comes to security, so please be patient with me. If any of the information I have put down is wrong or could be sub-sectioned then please feel free to say so.

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  • Multiple database with Spring+Hibernate+JPA

    - by ziftech
    Hi everybody! I'm trying to configure Spring+Hibernate+JPA for work with two databases (MySQL and MSSQL) my datasource-context.xml: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"> <!-- Data Source config --> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${local.jdbc.driver}" p:url="${local.jdbc.url}" p:username="${local.jdbc.username}" p:password="${local.jdbc.password}"> </bean> <bean id="dataSourceRemote" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${remote.jdbc.driver}" p:url="${remote.jdbc.url}" p:username="${remote.jdbc.username}" p:password="${remote.jdbc.password}" /> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" p:entity-manager-factory-ref="entityManagerFactory" /> <!-- JPA config --> <tx:annotation-driven transaction-manager="transactionManager" /> <bean id="persistenceUnitManager" class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager"> <property name="persistenceXmlLocations"> <list value-type="java.lang.String"> <value>classpath*:config/persistence.local.xml</value> <value>classpath*:config/persistence.remote.xml</value> </list> </property> <property name="dataSources"> <map> <entry key="localDataSource" value-ref="dataSource" /> <entry key="remoteDataSource" value-ref="dataSourceRemote" /> </map> </property> <property name="defaultDataSource" ref="dataSource" /> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" p:showSql="true" p:generateDdl="true"> </bean> </property> <property name="persistenceUnitManager" ref="persistenceUnitManager" /> <property name="persistenceUnitName" value="localjpa"/> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> </beans> each persistence.xml contains one unit, like this: <persistence-unit name="remote" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" /> <property name="hibernate.dialect" value="${remote.hibernate.dialect}" /> <property name="hibernate.hbm2ddl.auto" value="${remote.hibernate.hbm2ddl.auto}" /> </properties> </persistence-unit> PersistenceUnitManager cause following exception: Cannot resolve reference to bean 'persistenceUnitManager' while setting bean property 'persistenceUnitManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'persistenceUnitManager' defined in class path resource [config/datasource-context.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type [java.util.ArrayList] to required type [java.lang.String] for property 'persistenceXmlLocation'; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [java.util.ArrayList] to required type [java.lang.String] for property 'persistenceXmlLocation': no matching editors or conversion strategy found If left only one persistence.xml without list, every works fine but I need 2 units... I also try to find alternative solution for work with two databases in Spring+Hibernate context, so I would appreciate any solution new error after changing to persistenceXmlLocations No single default persistence unit defined in {classpath:config/persistence.local.xml, classpath:config/persistence.remote.xml} UPDATE: I add persistenceUnitName, it works, but only with one unit, still need help UPDATE: thanks, ChssPly76 I changed config files: datasource-context.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${local.jdbc.driver}" p:url="${local.jdbc.url}" p:username="${local.jdbc.username}" p:password="${local.jdbc.password}"> </bean> <bean id="dataSourceRemote" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${remote.jdbc.driver}" p:url="${remote.jdbc.url}" p:username="${remote.jdbc.username}" p:password="${remote.jdbc.password}"> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"> <property name="defaultPersistenceUnitName" value="pu1" /> </bean> <bean id="persistenceUnitManager" class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager"> <property name="persistenceXmlLocation" value="${persistence.xml.location}" /> <property name="defaultDataSource" ref="dataSource" /> <!-- problem --> <property name="dataSources"> <map> <entry key="local" value-ref="dataSource" /> <entry key="remote" value-ref="dataSourceRemote" /> </map> </property> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" p:showSql="true" p:generateDdl="true"> </bean> </property> <property name="persistenceUnitManager" ref="persistenceUnitManager" /> <property name="persistenceUnitName" value="pu1" /> <property name="dataSource" ref="dataSource" /> </bean> <bean id="entityManagerFactoryRemote" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" p:showSql="true" p:generateDdl="true"> </bean> </property> <property name="persistenceUnitManager" ref="persistenceUnitManager" /> <property name="persistenceUnitName" value="pu2" /> <property name="dataSource" ref="dataSourceRemote" /> </bean> <tx:annotation-driven /> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" p:entity-manager-factory-ref="entityManagerFactory" /> <bean id="transactionManagerRemote" class="org.springframework.orm.jpa.JpaTransactionManager" p:entity-manager-factory-ref="entityManagerFactoryRemote" /> </beans> persistence.xml <?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0"> <persistence-unit name="pu1" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" /> <property name="hibernate.dialect" value="${local.hibernate.dialect}" /> <property name="hibernate.hbm2ddl.auto" value="${local.hibernate.hbm2ddl.auto}" /> </properties> </persistence-unit> <persistence-unit name="pu2" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" /> <property name="hibernate.dialect" value="${remote.hibernate.dialect}" /> <property name="hibernate.hbm2ddl.auto" value="${remote.hibernate.hbm2ddl.auto}" /> </properties> </persistence-unit> </persistence> Now it builds two entityManagerFactory, but both are for Microsoft SQL Server [main] INFO org.hibernate.ejb.Ejb3Configuration - Processing PersistenceUnitInfo [ name: pu1 ...] [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: Microsoft SQL Server [main] INFO org.hibernate.ejb.Ejb3Configuration - Processing PersistenceUnitInfo [ name: pu2 ...] [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: Microsoft SQL Server (but must MySQL) I suggest, that use only dataSource, dataSourceRemote (no substitution) is not worked. That's my last problem

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  • Database design for summarized data

    - by holden
    I have a new table I'm going to add to a bunch of other summarized data, basically to take some of the load off by calculating weekly avgs. My question is whether I would be better off with one model over the other. One model with days of the week as a column with an additional column for price or another model as a series of fields for the DOW each taking a price. I'd like to know which would save me in speed and/or headaches? Or at least the trade off. IE. ID OBJECT_ID MON TUE WED THU FRI SAT SUN SOURCE OR ID OBJECT_ID DAYOFWEEK PRICE SOURCE

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  • Cross-platform embedded database/key-value store for C#

    - by Arne Claassen
    I'm looking for a fast, embeddable key/value store with cursor semantics over key collections (or a simple embeddable DB) that I can use in .NET and mono. Need it to be open-source, would prefer an MIT or Apache style license over a GPL license. Not opposed to a library that needs bindings to be written, as long as binaries are available for both windows and linux. Options considered: SQLite - has bindings and native implementation, but single-threaded and not all that fast Embedded InnoDB - no .NET bindings i can find and it's GPLv2 Berkley DB - no .NET bindings i can find Tokyo Cabinet - no .NET bindings i can find and problematic to build on windows MadCow Memory-mapped data structures - GPLv2 Is there an option better than the above that i'm missing, or bindings for the above i don't know about?

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  • Finding first alphabetic character in a DB2 database field

    - by Paul Alan Taylor
    I'm doing a bit of work which requires me to truncate DB2 character-based fields. Essentially, I need to discard all text which is found at or after the first alphabetic character. e.g. 102048994BLAHBLAHBLAH becomes:- 102048994 In SQL Server, this would be a doddle - PATINDEX would swoop in and save the day. Much celebration would ensue. My problem is that I need to do this in DB2. Worse, the result needs to be used in a join query, also in DB2. I can't find an easy way to do this. Is there a PATINDEX equivalent in DB2? Is there another way to solve this problem? If need be, I'll hardcode 26 chained LOCATE functions to get my result, but if there is a better way, I am all ears.

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  • general database modeling and django specific modeling

    - by Shreko
    I'm wondering what is the best way to model something like the following. Lets say my company sells metal bars (parameters/fields are: length, profile_type, quantity etc.) of different profiles, where profiles may be pipe(pipe_diameter, wall_thickness) or hollow_rectangle(base, height, wall_thickness), or maybe some other profile with different parameters. Lets say maximum number of profiles would be 12, each profile having between 2-5 parameters. Should everything be in a single table like table_bars: id, length, quantity, profile_type, pipe_diameter, wall_thickness, base, height, etc.) where profile type would be (pipe, rectangle etc.) or should every shape have its own table with its own parameters and in table_bars keep only id, length, quantity profile_type and profile_id) and are there any django specific issues is multiple tables are the best answer? Thanks

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  • Implementing database redundancy with sharded tables

    - by ensnare
    We're looking to implement load balancing by horizontally sharding our tables across a cluster of servers. What are some options to implement live redundancy should a server fail? Would it be effective to do (2) INSERTS instead of one ... one to the target shard, and another to a secondary shard which could be accessed should the primary shard not respond? Or is there a better way? Thanks.

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  • Tutorials for .NET database app using SQLite

    - by ChrisC
    I have some MS Access experience, and had a class on console c++ apps, now I am trying to develop my first program. It's a little C# db app. I have the db tables and columns planned and keyed into VS, but that's where I'm stuck. I'm needing C#/VS tutorials that will guide me on configuring relationships, datatyping, etc, on the db so I can get it ready for testing of the schema. The only tutorials I've been able to find either talk about general db basics (ie, not helping me with VS/C#), or about C# communications with an existing SQL db. Thank you. (In case it matters, I'm using the open source System.Data.SQLite (sqlite.phxsoftware.com) for the db. I chose it over SQL Server CE after seeing a comparison between the two. Also I wanted a server-less version of SQL because this little app will be on other people's computers and I want to to do as little support as possible.)

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  • Main pricing and support for individual client pricing (Database Architecture ideas help - Rails)

    - by slythic
    Hi all, I have a personal project I'm planning and I came to a small hurdle. I want to have an item with price that will be the default for all clients/users. However, in my business I have some clients that are grandfathered in to some special pricing. In the case of these grandfathered in cases, I'll manually plug their special price in my admin section. Then all they will see is their special pricing while the regular users/clients see the default price. What is the best and simplest way to design the back-end for this? FYI - I'll be using rails as my framework. Many thanks! -Tony

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  • Main pricing and support for custom client pricing (Database Architecture ideas help - Rails)

    - by slythic
    Hi all, I have a personal project I'm planning and I came to a small hurdle. I want to have an item with price that will be the default for all clients/users. However, in my business I have some clients that are grandfathered in to some special pricing. In the case of these grandfathered in cases, I'll manually plug their special price in my admin section. Then all they will see is their special pricing while the regular users/clients see the default price. What is the best and simplest way to design the back-end for this? FYI - I'll be using rails as my framework. Many thanks! -Tony

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  • database datatype size

    - by yeeen
    Just to clarify by specifying sth like VARCHAR(45) means it can take up to max 45 characters? I rmb I heard from someone a few years ago that the number in the parathesis doesn't refer to the no of characters, then the person tried to explain to me sth quite complicated which i don't understand n forgot alr. And what is the difference btn CHAR and VARCHAR? I did search ard a bit and see that CHAR gives u the max of the size of the column and it is better to use it if ur data has a fix size and use VARCHAR if ur data size varies. But if it gives u the max of the size of the column of all the data of this col, isn't it better to use it when ur data size varies? Esp if u don't know how big is ur data size gg to be. VARCHAR needs to specify the size (CHAR don't really need right?), isn't it more troublesome?

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  • Database warehouse design: fact tables and dimension tables

    - by morpheous
    I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to seek some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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  • EAV Database Sheme

    - by GLO
    Hello Stackoverflow comunity! I believe that my question has to do with all db guru here! Do you know the EAV DB Scheme ( http://en.wikipedia.org/wiki/Entity-attribute-value_model ) and what they say about the performing of this model. I wonder, If I break this model into smaller tables what the result is? Let's talk about it. I have a db with more that 100K records. A lot of categories and many items ( with different properties per category ) Everything is stored in a EAV. If I try to break this scheme and create for any category a unique table is something that will I have to avoid? Yes, I know that probably I'll have a lot of tables and I'll need to ALTER them if I want to add an extra field, BUT is this so wrong? I have also read that as many tables I have, the db will be populate with more files and this isn't good for any filesystem. Any suggestion? Thank you!

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