rdbms

When to replace RDBMS/ORM with NoSQL/DocumentStore

由 我只是一个虾纸丫 提交于 2019-12-08 21:20:30
I've looked at MongoDB/norm (but want a general document-oriented store answer). It seems really nice to work with and I'm interested in knowing when it should be used instead of RDBMS+ORM? What should i use for for instance: Stackoverflow similiar sites Social communities forums (I posted another more general question but it got a splendid answer that might be interesting for others, hence the new question) All of the examples you mentioned can be built using a document store. Whether you should use it, depends on the exact requirements. If you're dealing with a social community that supports

Help me to connect inheritance and relational concepts

由 吃可爱长大的小学妹 提交于 2019-12-08 19:25:15
问题 I was talking with a programmer pal of mine about inheritance and its use in designing models. He's a big proponent and I'm a little more tepid. Mostly because I tend to design systems from the bottom up: Database -> Application -> Presentation (honestly, I'm not much of a front-end guy, so I often leave presentation entirely to someone else). I find that relational database systems don't support inheritance without a lot of 1-to-1 relationships to other tables. If I'm designing from a

When to and when not to NATURAL JOIN?

由 懵懂的女人 提交于 2019-12-08 11:26:25
问题 I have been having this doubt for a while now, after some practices in SQL I started to ask myself: 'When is the right time to use NATURAL JOIN '? Due to the enormous size of the database example that I'm using to practice my SQL skills I'm just going to put two sample queries here. Let's say I want to Find, for each item, the total quantity sold by the departments on the second floor The sample answer of this question is: SELECT Item.ItemName, SUM(SaleQTY) FROM Item INNER JOIN Sale INNER

Apache Drill 1.2 and Oracle JDBC

由 半世苍凉 提交于 2019-12-08 06:11:39
问题 Using Apache Drill v1.2 and Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit in embedded mode. I'm curious if anyone has had any success connecting Apache Drill to an Oracle DB. I've updated the drill-override.conf with the following configurations (per documents): drill.exec: { cluster-id: "drillbits1", zk.connect: "localhost:2181", drill.exec.sys.store.provider.local.path = "/mypath" } and placed the ojdbc6.jar in \apache-drill-1.2.0\jars\3rdparty . I can successfully

Best practices for mixed usage of RDBMS and files on filesystem

由 妖精的绣舞 提交于 2019-12-08 04:48:16
问题 In one of the tables in the schema I am working on, I need to deal with couple-of thousand "data-sheets" which are mostly PDF documents, and sometimes graphic-image files like PNG, JPG etc. The schema models a Electronics Distributor's portal, where new products get added to their portfolio frequently. These documents (data-sheets) are added, at the time of introduction of a new product, but they need updates from time to time (s.a. due to newer version of the document, not the product itself

When to replace RDBMS/ORM with NoSQL/DocumentStore

由 元气小坏坏 提交于 2019-12-08 04:19:55
问题 I've looked at MongoDB/norm (but want a general document-oriented store answer). It seems really nice to work with and I'm interested in knowing when it should be used instead of RDBMS+ORM? What should i use for for instance: Stackoverflow similiar sites Social communities forums (I posted another more general question but it got a splendid answer that might be interesting for others, hence the new question) 回答1: All of the examples you mentioned can be built using a document store. Whether

Apache Drill 1.2 and Oracle JDBC

由 混江龙づ霸主 提交于 2019-12-08 03:44:25
Using Apache Drill v1.2 and Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit in embedded mode. I'm curious if anyone has had any success connecting Apache Drill to an Oracle DB. I've updated the drill-override.conf with the following configurations (per documents): drill.exec: { cluster-id: "drillbits1", zk.connect: "localhost:2181", drill.exec.sys.store.provider.local.path = "/mypath" } and placed the ojdbc6.jar in \apache-drill-1.2.0\jars\3rdparty . I can successfully create the storage plug-in: { "type": "jdbc", "driver": "oracle.jdbc.driver.OracleDriver", "url": "jdbc

Why use primary keys?

由 落花浮王杯 提交于 2019-12-07 10:45:10
问题 What are primary keys used aside from identifying a unique column in a table? Couldn't this be done by simply using an autoincrement constraint on a column? I understand that PK and FK are used to relate different tables, but can't this be done by just using join? Basically what is the database doing to improve performance when joining using primary keys? 回答1: Mostly for referential integrity with foreign keys,, When you have a PK it will also create an index behind the scenes and this way

ORMs are to RDBMSs as xxx is to OLAP cubes? Does xxx exist?

由 怎甘沉沦 提交于 2019-12-07 05:08:06
问题 Is there an ORM-analogue for querying OLAP cubes / data-warehouses? I'm specifically interested in the .NET world, but generally interested in anything ;-) 回答1: I've started an open source project, Kona, to wrap the ADOMD.Net lib, and try to bring ADOMD.Net into the 21st Century. You can get it up at http://www.codeplex.com/kona, but it does need some more love and attention. The task of converting lambdas to MDX isn't a small one, so I haven't even tried to to that, yet. I've tried to

Why is Select 1 faster than Select count(*)?

由 断了今生、忘了曾经 提交于 2019-12-06 20:27:36
问题 In Oracle, when querying for row existence, why is Select 1 fast than Select count(*)? 回答1: Since Oracle doesn't support IF EXISTS in PL/SQL, CodeByMidnight's suggestion to use EXISTS would normally be done with something like SELECT 1 INTO l_local_variable FROM dual WHERE EXISTS( SELECT 1 FROM some_table WHERE some_column = some_condition ); Oracle knows that it can stop processing the WHERE EXISTS clause as soon as one row is found, so it doesn't have to potentially count a large number of
订阅 rdbms