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• Schema design: many to many plus additional one to many

  - by chrisj

  Hi, I have this scenario and I'm not sure exactly how it should be modeled in the database. The objects I'm trying to model are: teams, players, the team-player membership, and a list of fees due for each player on a given team. So, the fees depend on both the team and the player. So, my current approach is the following: **teams** id name **players** id name **team_players** id player_id team_id **team_player_fees** id team_players_id amount send_reminder_on Schema layout ERD In this schema, team_players is the junction table for teams and players. And the table team_player_fees has records that belong to records to the junction table. For example, playerA is on teamA and has the fees of $10 and $20 due in Aug and Feb. PlayerA is also on teamB and has the fees of $25 and $25 due in May and June. Each player/team combination can have a different set of fees. Questions: Are there better ways to handle such a scenario? Is there a term for this type of relationship? (so I can google it) Or know of any references with similar structures?

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• Database Schema Usage

  - by CrazyHorse

  I have a question regarding the appropriate use of SQL Server database schemas and was hoping that some database gurus might be able to offer some guidance around best practice. Just to give a bit of background, my team has recently shrunk to 2 people and we have just been merged with another 6 person team. My team had set up a SQL Server environment running off a desktop backing up to another desktop (and nightly to the network), whilst the new team has a formal SQL Server environment, running on a dedicated server, with backups and maintenance all handled by a dedicated team. So far it's good news for my team. Now to the query. My team designed all our tables to belong to a 3-letter schema name (e.g. User = USR, General = GEN, Account = ACC) which broadly speaking relate to specific applications, although there is a lot of overlap. My new team has come from an Access background and have implemented their tables within dbo with a 3-letter perfix followed by "_tbl" so the examples above would be dbo.USR_tblTableName, dbo.GEN_tblTableName and dbo.ACC_tblTableName. Further to this, neither my old team nor my new team has gone live with their SQL Servers yet (we're both coincidentally migrating away from Access environments) and the new team have said they're willing to consider adopting our approach if we can explain how this would be beneficial. We are not anticipating handling table updates at schema level, as we will be using application-level logins. Also, with regards to the unwieldiness of the 7-character prefix, I'm not overly concerned myself as we're using LINQ almost exclusively so the tables can simply be renamed in the DMBL (although I know that presents some challenges when we update the DBML). So therefore, given that both teams need to be aligned with one another, can anyone offer any convincing arguments either way?

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• Design considerations on JSON schema for scalars with a consistent attachment property

  - by casperOne

  I'm trying to create a JSON schema for the results of doing statistical analysis based on disparate pieces of data. The current schema I have looks something like this: { // Basic key information. video : "http://www.youtube.com/watch?v=7uwfjpfK0jo", start : "00:00:00", end : null, // For results of analysis, to be populated: // *** This is where it gets interesting *** analysis : { game : { value: "Super Street Fighter 4: Arcade Edition Ver. 2012", confidence: 0.9725 } teams : [ { player : { value : "Desk", confidence: 0.95, } characters : [ { value : "Hakan", confidence: 0.80 } ] } ] } } The issue is the tuples that are used to store a value and the confidence related to that value (i.e. { value : "some value", confidence : 0.85 }), populated after the results of the analysis. This leads to a creep of this tuple for every value. Take a fully-fleshed out value from the characters array: { name : { value : "Hakan", confidence: 0.80 } ultra : { value: 1, confidence: 0.90 } } As the structures that represent the values become more and more detailed (and more analysis is done on them to try and determine the confidence behind that analysis), the nesting of the tuples adds great deal of noise to the overall structure, considering that the final result (when verified) will be: { name : "Hakan", ultra : 1 } (And recall that this is just a nested value) In .NET (in which I'll be using to work with this data), I'd have a little helper like this: public class UnknownValue<T> { T Value { get; set; } double? Confidence { get; set; } } Which I'd then use like so: public class Character { public UnknownValue<Character> Name { get; set; } } While the same as the JSON representation in code, it doesn't have the same creep because I don't have to redefine the tuple every time and property accessors hide the appearance of creep. Of course, this is an apples-to-oranges comparison, the above is code while the JSON is data. Is there a more formalized/cleaner/best practice way of containing the creep of these tuples in JSON, or is the approach above an accepted approach for the type of data I'm trying to store (and I'm just perceiving it the wrong way)? Note, this is being represented in JSON because this will ultimately go in a document database (something like RavenDB or elasticsearch). I'm not concerned about being able to serialize into the object above, because I can always use data transfer objects to facilitate getting data into/out of my underlying data store.

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• Controlling what data populates STAR

  - by user10747017

  Beginning with the Primavera Reporting Database 2.2\P6 Analytics 1.2 release, the first release that supported the P6 Extended Schema, a new ability was added to filter which projects could be included during an ETL run. In previous releases, all projects were included in an ETL run. Additionally, all projects with the option to enable publication are included in the ETL run by default.Because the reporting needs for P6 Extended Schema are different from those of STAR, you can define a filter that will limit the data that is included in the STAR schema. For example, your STAR schema can be filter to only include all projects in a specific Portfolio, or all projects with a project code assignment of 'For Analytics.'  Any criteria that can be defined in a Where clause and added to a view can be used to filter the projects included in the STAR schema. I highly suggest this approach when dealing with large databases. Unnecessary projects could cause the Extract portion of the ETL process to take longer. A table in STAR called etl_projectlist is the key for what projects are targeted during the ETL process. To setup the filter, perform the following steps:1. Connect to your Primavera P6 Project Management Database as Pxrptuser (extended schema owner) and create a new view:create or replace view star_project_viewasselect PROJECTOBJECTID objectidfrom projectportfolio pp, projectprojectportfolio pppwhere pp.objectid = ppp.PROJECTPORTFOLIOOBJECTIDand pp.name = 'STAR Projects'--The main field that MUST be selected in the view is the projectobjectid. Selecting any other field besides the projectobjectid will cause the view to be invalid and will not work. Any Where clause can be used, but projectobjectid is the key.2. In your STAR installation directory go the \res folder and edit the staretl.properties file.  Here you will define the view to be used.  Add the following line or update if exists:star.project.filter.ds1=star_project_view3. When running the  staretl.cmd or staretl.sh process the database link to Pxrtpuser will be accessed and this view will be used to populate the etl_projectlist table  with the appropriate projectobjectids as defined in the view created in step 1 above.

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• Does schema.org improve SEO?

  - by marko

  http://schema.org This site provides a collection of schemas, i.e., html tags, that webmasters can use to markup their pages in ways recognized by major search providers. Search engines including Bing, Google, Yahoo! and Yandex rely on this markup to improve the display of search results, making it easier for people to find the right web pages. It sounds wonderful, but does the search spider ignore the extra attributes and elements? Is it just too clever and ignores it? May it also be that it lowers your visibility because of such alteration?

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• Database with "Open Schema" - Good or Bad Idea?

  - by Claudiu

  The co-founder of Reddit gave a presentation on issues they had while scaling to millions of users. A summary is available here. What surprised me is point 3: Instead, they keep a Thing Table and a Data Table. Everything in Reddit is a Thing: users, links, comments, subreddits, awards, etc. Things keep common attribute like up/down votes, a type, and creation date. The Data table has three columns: thing id, key, value. There’s a row for every attribute. There’s a row for title, url, author, spam votes, etc. When they add new features they didn’t have to worry about the database anymore. They didn’t have to add new tables for new things or worry about upgrades. This seems like a terrible idea to me, but it seems to have worked out for Reddit. Is it a good idea in general, though? Or is it a peculiarity of Reddit that happened to work out for them?

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• Star Trail Photos Taken from the International Space Station

  - by Jason Fitzpatrick

  While most people have seen a star trail photo or two, seeing a set of star trail photos taken from over 300 miles above the Earth’s surface is a treat. Courtesy of Astronaut and Expedition 31 Flight Engineer Don Pettit, the photos capture star trails from the vantage point of the International Space Station. He explains his technique: My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, then ‘stack’ them using imaging software, thus producing the longer exposure. Hit up the link below for the full Flickr set of the star trails. ISS Star Trails [via Smithsonian Magazine] HTG Explains: What Is RSS and How Can I Benefit From Using It? HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It HTG Explains: Learn How Websites Are Tracking You Online

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• Why my test xml is failing with very simple XSD Schema?

  - by JSteve

  Hi all, I am a bit novice in xml schema. I would be grateful if somebody help me out to understand why my xml is not being validated with the schema: Here is my Schema: <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.example.org/testSchema" xmlns="http://www.example.org/testSchema"> <xs:element name="Employee"> <xs:complexType> <xs:sequence> <xs:element name="Name"> <xs:complexType> <xs:sequence> <xs:element name="FirstName" /> <xs:element name="LastName" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> Here is my test xml: <?xml version="1.0" encoding="UTF-8"?> <Employee xmlns="http://www.example.org/testSchema"> <Name> <FirstName>John</FirstName> <LastName>Smith</LastName> </Name> </Employee> I am getting following error by Eclipse xml editor/validator: cvc-complex-type.2.4.a: Invalid content was found starting with element 'Name'. One of '{Name}' is expected. I could not understand what is wrong with this schema or my xml.

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• How Star Wars Changed the World [Infographic]

  - by ETC

  The Star Wars film franchise has had an enormous impact on the world of film, gaming, and special effects. Check out this interesting infographic to see how Star Wars has impacted the world. Created by Michelle Devereau, the “How Star Wars Changed the World” infographic is a massive under taking of charting and cross-referencing. It does an excellent job highlighting the impact the Star Wars films have had on film, television, gaming, and the surrounding technologies. At minimum you’ll nail down some new trivia (I learned, for example, that famed puppeteer and voice actor Frank Oz was the man behind Yoda), even better you’ll have an appreciate for what a sweeping effect Star Wars has had. For readers behind finicky firewalls, click here to view a local mirror of the image. How Star Wars Changed the World [Daily Infographic] Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Reclaim Vertical UI Space by Moving Your Tabs to the Side in Firefox Wind and Water: Puzzle Battles – An Awesome Game for Linux and Windows How Star Wars Changed the World [Infographic] Tabs Visual Manager Adds Thumbnailed Tab Switching to Chrome Daisies and Rye Swaying in the Summer Wind Wallpaper Read On Phone Pushes Data from Your Desktop to the Appropriate Android App

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• Practical mysql schema advice for eCommerce store - Products & Attributes

  - by Gravy

  I am currently planning my first eCommerce application (mySQL & Laravel Framework). I have various products, which all have different attributes. Describing products very simply, Some will have a manufacturer, some will not, some will have a diameter, others will have a width, height, depth and others will have a volume. Option 1: Create a master products table, and separate tables for specific product types (polymorphic relations). That way, I will not have any unnecessary null fields in the products table. Option 2: Create a products table, with all possible fields despite the fact that there will be a lot of null rows Option 3: Normalise so that each attribute type has it's own table. Option 4: Create an attributes table, as well as an attribute_values table with the value being varchar regardless of the actual data-type. The products table would have a many:many relationship with the attributes table. Option 5: Common attributes to all or most products put in the products table, and specific attributes to a particular category of product attached to the categories table. My thoughts are that I would like to be able to allow easy product filtering by these attributes and sorting. I would also want the frontend to be fast, less concern over the performance of the inserting and updating of product records. Im a bit overwhelmed with the vast implementation options, and cannot find a suitable answer in terms of the best method of approach. Could somebody point me in the right direction? In an ideal world, I would like to offer the following kind of functionality - http://www.glassesdirect.co.uk/products/ to my eCommerce store. As can be seen, in the sidebar, you can select an attribute the glasses to filter them. e.g. male / female or plastic / metal / titanium etc... Alternatively, should I just dump the mySql relational database idea and learn mongodb?

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• Declraing namespace schema with prefix in XSD/XML

  - by user1493537

  I am new to XML and I have a couple of questions about prefix. I need to "add the root schema element and insert the declaration for the XML schema namespace using the xc prefix. Set the default namespace and target of the schema to the URI test.com/test1" I am doing: <xc:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://test.com/test1" targetNamespace="http://test.com/test1"> </xc:schema> Is this correct? The next one is: "insert the root schema element, declaring the XML schema namespace with the xc prefix. Declare the library namespace using the lib prefix and the contributors namespace using the cont prefix. Set the default namespace and the schema target to URI test.com/test2" The library URI is http://test.com/library and contributor URI is test.com/contributor I am doing: <xc:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:lib="http://test.com/library" xmlns:clist="http://test.com/contributor" targetNamespace="http://test.com/test2"> </xc:schema> Does this look right? I am confused with prefix and all. Thanks for the help.

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• In-document schema declarations and lxml

  - by shylent

  As per the official documentation of lxml, if one wants to validate a xml document against a xml schema document, one has to construct the XMLSchema object (basically, parse the schema document) construct the XMLParser, passing the XMLSchema object as its schema argument parse the actual xml document (instance document) using the constructed parser There can be variations, but the essense is pretty much the same no matter how you do it, - the schema is specified 'externally' (as opposed to specifying it inside the actual xml document). If you follow this procedure, the validation occurs, sure enough, but if I understand it correctly, that completely ignores the whole idea of the schemaLocation and noNamespaceSchemaLocation attributes from xsi. This introduces a whole bunch of limitations, starting with the fact, that you have to deal with instance<-schema relation all by yourself (either store it externally or write some hack to retrieve the schema location from the root element of the instance document), you can not validate the document using multiple schemata (say, when each schema governs its own namespace) and so on. So the question is: maybe I am missing something completely trivial or doing it wrong? Or are my statements about lxml's limitations regarding schema validation true? To recap, I'd like to be able to: have the parser use the schema location declarations in the instance document at parse/validation time use multiple schemata to validate a xml document declare schema locations on non-root elements (not of extreme importance) Maybe I should look for a different library? Although, that'd be a real shame, - lxml is a de-facto xml processing library for python and is regarded by everyone as the best one in terms of performace/features/convenience (and rightfully so, to a certain extent)

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• Need Tech Support? Call the Star Wars Help Desk! [Video Classic]

  - by Asian Angel

  Having problems with the Tractor Beam? Did a weapons malfunction bring your computer system down? Is the Replicator making your Earl Grey Tea taste odd? Wait…what??!! Just call the Star Wars Help Desk to get the personalized help you need. Star Wars Help Desk [YouTube] Latest Features How-To Geek ETC How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware Comix is an Awesome Comics Archive Viewer for Linux Get the MakeUseOf eBook Guide to Speeding Up Windows for Free Need Tech Support? Call the Star Wars Help Desk! [Video Classic] Reclaim Vertical UI Space by Adding a Toolbar to the Left or Right Side of Firefox Androidify Turns You into an Android-style Avatar Reader for Android Updates; Now with Feed Widgets and More

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• Insert into a star-schema

  - by shaun

  I've read a lot about star-schema's, about fact/deminsion tables, select statements to quickly report data, however the matter of data entry into a star-schema seems aloof to me. How does one "theoretically" enter data into a star-schema db? while maintaining the fact table. Is a series of INSERT INTO statement within giant stored proc with 20 params my only option (and how to populate the fact table). Many thanks.

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• codeto draw a star

  - by adnan baig

  code to draw two filled star

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• Oracle Schema Design: Seperate Schema with I/O Overhead?

  - by Guru

  We are designing database schema for a new system based on Oracle 11gR1. We have identified a main schema which would have close to 100 tables, these will be accessed from the front end Java application. We have a requirement to audit the values which got changed in close to 50 tables, this has to be done every row. Which means, it is possible that, for a single row in MYSYS.T1 there might be 50 (or more) rows in MYSYS_AUDIT.T1_AUD table. We might be having old values of every column entry and new values available from T1. DBA gave an observation, advising against this method, because he said, separate schema meant an extra I/O for every operation. Basically AUDIT schema would be used only to do some analyse and enter values (thus SELECT and INSERT). Is it true that, "a separate schema means an extra I/O" ? I could not find justification. It appears logical to me, as the AUDIT data should not be tampered with, so a separate schema. Also, we designed a separate schema for archiving some tables from MYSYS. From MYSYS_ARC the table might be backed up into tapes or deleted after sufficient time. Few stats: Few tables (close to 20, 30) in MYSYS schema could grow to around 50M rows. We have asked for a total disk space of 4 TB. MYSYS_AUDIT schema might be having 10 times that of MYSYS but we wont keep them more than 3 months. Questions Given all these, can you suggest me any improvements? Separate schema affects disc I/O? (one extra I/O for every schema ?) Any general suggestions? Figure: +-------------------+ +-------------------+ | MYSYS | | MYSYS_AUDIT | | | | | | 1. T1 | | 1. T1_AUD | | 2. T2 | | 2. T2_AUD | | 3. T3 |--------->| 3. T3_AUD | | 4. T4 |(SELECT, | 4. T4_AUD | | . | INSERT) | . | | . | | . | | . | | . | | 100. T100 | | 50. T50_AUD | +-------------------+ +-------------------+ | | | | |(INSERT) | | | * +-------------------+ | MYSYS_ARC | | | | 1. T1_ARC | | 2. T2_ARC | | 3. T3_ARC | | 4. T4_ARC | | . | | . | | . | | 100. T100_ARC | +-------------------+ Apart from this, we have two more schemas with only read only rights, but mainly they are for adhoc purpose and we dont mind the performance on them.

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• Schema changes with replication

  - by Even Mien

  What are the steps to make a schema change to a SQL Server 2005 database using transactional replication? I'm trying to add a database column. I thought if I removed the article for the table, made the schema change, and then added the article for the table back that the schema change would replicate. I am now getting the following error every minute or so: SQL Server errors Replication-Replication Distribution Subsystem: agent [jobname] failed. Invalid column name 'NewColumn'.

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• add schema to path in postgresql

  - by veilig

  I'm the process of moving applications over from all in the public schema to each having their own schema. for each application, I have a small script that will create the schema and then create the tables,functions,etc... to that schema. Is there anyway to automatically add a newly created schema to the search_path? Currently, the only way I see is to find the users current path SHOW search_path; and then add the new schema to it SET search_path to xxx,yyy,zzz; I would like some way to just say, append schema zzz to the users_search path. is this possible?

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• Sqlite catalog and schema settings (for MyBatis generator)

  - by user1769754

  I have been trying to use the MyBatis generator on a Sqlite database but can't seem to find what settings to use for the XML attributes catalog and schema. The generator errors with "Generation Warnings Occured: Table configuration with catalog main, schema sqlite_master, and table testTable did not resolve to any tables" I can't find much from the sqlite website other than this which gives something like catalog = main, schema = sqlite or sqlite_master My generator XML file is <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd" > <generatorConfiguration > <context id="context"> <jdbcConnection driverClass="org.sqlite.JDBC" connectionURL="jdbc:sqlite:testDB.sqlite" userId="" password="" ></jdbcConnection> <javaModelGenerator targetPackage="model" targetProject="test/src" ></javaModelGenerator> <sqlMapGenerator targetPackage="model" targetProject="test/src" ></sqlMapGenerator> <javaClientGenerator targetPackage="model" targetProject="test" type="XMLMAPPER" ></javaClientGenerator> <table catalog="main" schema="sqlite_master" tableName="testTable" > <property name="useActualColumnNames" value="true"/> </table> </context> </generatorConfiguration> I have also tried other combinations like <table catalog="main" schema="sqlite" tableName="testTable" > <table schema="sqlite" tableName="testTable" > <table schema="sqlite_master" tableName="testTable" > <table schema="main.testTable" tableName="testTable" > Anyone here know the right settings?

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• VB.Net Validate an xml against a schema (strange problem)

  - by Apeksha

  I have written a small XML validator, that takes in an XML file and an XML schema and validates the XML files against that schema. It works well, except for an XML file, with this content: <?xml version="1.0" encoding="utf-8"?> <xc:program xmlns:xc="http:\\www.something.com\Schema\XC10" xc:version="4.0.22.0" > <xc:namespaceDecls> <xc:namespaceDecl xc:namespaceDeclURI="urn:swift:xsd:abc"> <xc:namespaceDeclPrefix>n</xc:namespaceDeclPrefix> </xc:namespaceDecl> </xc:namespaceDecls> </xc:program> I tried to validate this XML file against a bunch of different schemas. No matter which schema I select, this XML file comes out as valid. What is it that I am missing? Here is the relevant piece of code: 'Create a schema cache and add the given schema to it. Dim schemaCache As New Schema.XmlSchemaSet schemaCache.Add(targetNamespace, schemaFilename) 'Create an XML DOMDocument object. Dim xmlDom As New XmlDocument 'Assign the schema cache to the DOM document. 'schemas collection. xmlDom.Schemas = schemaCache 'Load selected file as the DOM document. xmlDom.Load(xmlFilename) xmlDom.Validate(AddressOf ValidationCallBack)

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• Automated Oracle Schema Migration Tool

  - by Dave Jarvis

  What are some tools (commercial or OSS) that provide a GUI-based mechanism for creating schema upgrade scripts? To be clear, here are the tool responsibilities: Obtain connection to recent schema version (called "source"). Obtain connection to previous schema version (called "target"). Compare all schema objects between source and target. Create a script to make the target schema equivalent to the source schema ("upgrade script"). Create a rollback script to revert the source schema, used if the upgrade script fails (at any point). Create individual files for schema objects. The software must: Use ALTER TABLE instead of DROP and CREATE for renamed columns. Work with Oracle 10g or greater. Create scripts that can be batch executed (via command-line). Trivial installation process. (Bonus) Create scripts that can be executed with SQL*Plus. Here are some examples (from StackOverflow, ServerFault, and Google searches): Change Manager Oracle SQL Developer Software that does not meet the criteria, or cannot be evaluated, includes: TOAD PL/SQL Developer - Invalid SQL*Plus statements. Does not produce ALTER statements. SQL Fairy - No installer. Complex installation process. Poorly documented. DBDiff - Crippled data set evaluation, poor customer support. OrbitDB - Crippled data set evaluation. SchemaCrawler - No easily identifiable download version for Oracle databases. SQL Compare - SQL Server, not Oracle. LiquiBase - Requires changing the development process. No installer. Manually edit config files. Does not recognize its own baseUrl parameter. The only acceptable crippling of the evaluation version is by time. Crippling by restricting the number of tables and views hides possible bugs that are only visible in the software during the attempt to migrate hundreds of tables and views.

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• Testing for Active Directory Schema modification (not upgrade)

  - by Darktux

  I am trying to test a schema modification. That is i need to add one of the attributes to global catalog by modifying schema , initially in a lab which is exact replica.My questions are below; - What tests need to be done post schema change to determine if its safe for production? - Apart from measuring changes in DIT size post change, is there a way to find the whole size increase for adding an attribute to GC pre change? please let me know if any extra questions or info required.

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• How does Dijkstra's Algorithm and A-Star compare?

  - by KingNestor

  I was looking at what the guys in the Mario AI Competition have been doing and some of them have built some pretty neat Mario bots utilizing the A* (A-Star) Pathing Algorithm. (Video of Mario A* Bot In Action) My question is, how does A-Star compare with Dijkstra? Looking over them, they seem similar. Why would someone use one over the other? Especially in the context of pathing in games?

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• JPA 2.1 Schema Generation (TOTD #187)

  - by arungupta

  This blog explained some of the key features of JPA 2.1 earlier. Since then Schema Generation has been added to JPA 2.1. This Tip Of The Day (TOTD) will provide more details about this new feature in JPA 2.1. Schema Generation refers to generation of database artifacts like tables, indexes, and constraints in a database schema. It may or may not involve generation of a proper database schema depending upon the credentials and authorization of the user. This helps in prototyping of your application where the required artifacts are generated either prior to application deployment or as part of EntityManagerFactory creation. This is also useful in environments that require provisioning database on demand, e.g. in a cloud. This feature will allow your JPA domain object model to be directly generated in a database. The generated schema may need to be tuned for actual production environment. This usecase is supported by allowing the schema generation to occur into DDL scripts which can then be further tuned by a DBA. The following set of properties in persistence.xml or specified during EntityManagerFactory creation controls the behaviour of schema generation. Property Name Purpose Values javax.persistence.schema-generation-action Controls action to be taken by persistence provider "none", "create", "drop-and-create", "drop" javax.persistence.schema-generation-target Controls whehter schema to be created in database, whether DDL scripts are to be created, or both "database", "scripts", "database-and-scripts" javax.persistence.ddl-create-script-target, javax.persistence.ddl-drop-script-target Controls target locations for writing of scripts. Writers are pre-configured for the persistence provider. Need to be specified only if scripts are to be generated. java.io.Writer (e.g. MyWriter.class) or URL strings javax.persistence.ddl-create-script-source, javax.persistence.ddl-drop-script-source Specifies locations from which DDL scripts are to be read. Readers are pre-configured for the persistence provider. java.io.Reader (e.g. MyReader.class) or URL strings javax.persistence.sql-load-script-source Specifies location of SQL bulk load script. java.io.Reader (e.g. MyReader.class) or URL string javax.persistence.schema-generation-connection JDBC connection to be used for schema generation javax.persistence.database-product-name, javax.persistence.database-major-version, javax.persistence.database-minor-version Needed if scripts are to be generated and no connection to target database. Values are those obtained from JDBC DatabaseMetaData. javax.persistence.create-database-schemas Whether Persistence Provider need to create schema in addition to creating database objects such as tables, sequences, constraints, etc. "true", "false" Section 11.2 in the JPA 2.1 specification defines the annotations used for schema generation process. For example, @Table, @Column, @CollectionTable, @JoinTable, @JoinColumn, are used to define the generated schema. Several layers of defaulting may be involved. For example, the table name is defaulted from entity name and entity name (which can be specified explicitly as well) is defaulted from the class name. However annotations may be used to override or customize the values. The following entity class: @Entity public class Employee {    @Id private int id;    private String name;     . . .     @ManyToOne     private Department dept; } is generated in the database with the following attributes: Maps to EMPLOYEE table in default schema "id" field is mapped to ID column as primary key "name" is mapped to NAME column with a default VARCHAR(255). The length of this field can be easily tuned using @Column. @ManyToOne is mapped to DEPT_ID foreign key column. Can be customized using JOIN_COLUMN. In addition to these properties, couple of new annotations are added to JPA 2.1: @Index - An index for the primary key is generated by default in a database. This new annotation will allow to define additional indexes, over a single or multiple columns, for a better performance. This is specified as part of @Table, @SecondaryTable, @CollectionTable, @JoinTable, and @TableGenerator. For example: @Table(indexes = {@Index(columnList="NAME"), @Index(columnList="DEPT_ID DESC")})@Entity public class Employee {    . . .} The generated table will have a default index on the primary key. In addition, two new indexes are defined on the NAME column (default ascending) and the foreign key that maps to the department in descending order. @ForeignKey - It is used to define foreign key constraint or to otherwise override or disable the persistence provider's default foreign key definition. Can be specified as part of JoinColumn(s), MapKeyJoinColumn(s), PrimaryKeyJoinColumn(s). For example: @Entity public class Employee {    @Id private int id;    private String name;    @ManyToOne    @JoinColumn(foreignKey=@ForeignKey(foreignKeyDefinition="FOREIGN KEY (MANAGER_ID) REFERENCES MANAGER"))    private Manager manager;     . . . } In this entity, the employee's manager is mapped by MANAGER_ID column in the MANAGER table. The value of foreignKeyDefinition would be a database specific string. A complete replay of Linda's talk at JavaOne 2012 can be seen here (click on CON4212_mp4_4212_001 in Media). These features will be available in GlassFish 4 promoted builds in the near future. JPA 2.1 will be delivered as part of Java EE 7. The different components in the Java EE 7 platform are tracked here. JPA 2.1 Expert Group has released Early Draft 2 of the specification. Section 9.4 and 11.2 provide all details about Schema Generation. The latest javadocs can be obtained from here. And the JPA EG would appreciate feedback.

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• Validating an XML document fragment against XML schema

  - by shylent

  Terribly sorry if I've failed to find a duplicate of this question. I have a certain document with a well-defined document structure. I am expressing that structure through an XML schema. That data structure is operated upon by a RESTful service, so various nodes and combinations of nodes (not the whole document, but fragments of it) are exposed as "resources". Naturally, I am doing my own validation of the actual data, but it makes sense to validate the incoming/outgoing data against the schema as well (before the fine-grained validation of the data). What I don't quite grasp is how to validate document fragments given the schema definition. Let me illustrate: Imagine, the example document structure is: <doc-root> <el name="foo"/> <el name="bar"/> </doc-root> Rather a trivial data structure. The schema goes something like this: <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="doc-root"> <xsd:complexType> <xsd:sequence> <xsd:element name="el" type="myCustomType" /> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:complexType name="myCustomType"> <xsd:attribute name="name" use="required" /> </xsd:complexType> </xsd:schema> Now, imagine, I've just received a PUT request to update an 'el' object. Naturally, I would receive not the full document or not any xml, starting with 'doc-root' at its root, but the 'el' element itself. I would very much like to validate it against the existing schema then, but just running it through a validating parser wouldn't work, since it will expect a 'doc-root' at the root. So, again, the question is, - how can one validate a document fragment against an existing schema, or, perhaps, how can a schema be written to allow such an approach. Hope it made sense.

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