I finished my course on Oracle databases and have been playing with it since sometime. One of my friends told me that PostgreSQL is a very good database management system which has object oriented capabilities.
On an Oracle database, it is a straightforward and easy process to create materialized views. BUT despite of having heard that PostgreSQL supports materialized views from few people, I am unable to figure out how to do that.
Please advise.
For PostgreSQL version 9.2 and below, read the following article on how to create materialized views by using functions and triggers.
http://tech.jonathangardner.net/wiki/PostgreSQL/Materialized_Views
Since version 9.3, materialized views are natively supported:
For more information on this topic, please refer to the following articles on PostgreSQL documentation:
http://www.postgresql.org/docs/devel/static/sql-creatematerializedview.html
http://www.postgresql.org/docs/devel/static/rules-materializedviews.html
There's no native support for materialized views in postgres.
You could try to emulate them with triggers/stored procedures as described in this article.
Related
I need to start a long-term project in mapping out data tables so that we can get a high-level view of what information we store in our Oracle database and how the tables are linked to each other. This is largely for GDPR preparation.
Since our organization has been around for a number of decades, its database is massive. With TOAD for Oracle, I'm able to see all columns in our tables easily, so I started looking at different database mapping tools (ER/ONE, DDM, Astah) but they all look like I need to manually create all the tables and columns and draw their relationships out by hand.
I'm hoping to minimize as much manual labor as possible and am wondering if using TOAD data modeler would help since I'm using TOAD for Oracle anyways. Could I somehow automate the table, column, and relationship creation process?
Our organization only has Oracle's base version unfortunately (I think the premium bundle has data mapper included in it maybe... not sure.) Any thoughts on the options I have?
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Bundle: Toad for Oracle Base (64-bit), Add-Ons: <-none->
Our organization only has Oracle's base version
Note: TOAD is not an Oracle product, it is owned and developed by Quest.
they all look like I need to manually create all the tables and columns and draw their relationships out by hand
Any decent data modelling tool supports reverse engineer a physical data model from an existing schema. How good the derived model is will depend on how good your schema is (my bet: decades of development without an existing data modelling tool? not good). For instance, if your schema has foreign keys the reverse engineering process will use them to draw the relationships between tables (even if they are disabled). But if there are no foreign keys then you're on your own.
As you're using already TOAD you are right to want the TOAD modelling extension. You can buy it as a standalone purchase. But if your company won't spring for the extra licenses you should check out Oracle SQL Developer Data Modeler. It's free and it has the most comprehensive support for idiomatic Oracle. (I'm not saying it's the best DM tool of them all but it's very good for something which is free). Find out more.
Let's imagine a standard situation.
Having the current DB schema in a working state, I would like to create a snapshot of this state of schema objects, name it SNAP_1.
Then if updated schema and got problems (bugs or unstable work of new code) it would be good to switch quickly - in one command - the whole schema code back to SNAP_1.
I'm wondering is there any built-in feature of Oracle DBMS for versioning:
PL/SQL code (schema objects)
Data (for example, within configuration tables)
Does Oracle DBMS give native tools for versioning at least one of these two?
The answer is no. But Oracle 11.2+ has something called "Editions".
This method has many restrictions. For example, data and table structure cannot be versioned.
Cool thing is that separate sessions can use a different version of the DB objects simultaneously. (package before fix and after fix)
Here is oracle's documentation.EDITION and
Examples of editions
We are developing a large data migration from Oracle DB (12c) to another system with SSIS. The developers are using a production copy database but the problem is that, due to the complexity of the data transformation, we have to do things in stages by preprocessing data into intermediate helper tables which are then used further downstream. The problem is that all developers are using the same database and screw each other up by running things simultaneously. Does Oracle DB offer anything in terms of developer sandboxing? We could build a mechanism to handle this (e.g. have dev ID in the helper tables, then query views that map to the dev), but I'd much rather use built-in functionality. Could I use Oracle Multitenant for this?
We ended up producing a master subset database of select schemas/tables through some fairly elaborate PL/SQL, then made several copies of this master schema so each dev has his/her own sandbox (as Alex suggested). We could have used Oracle Data Masking and Subsetting but it's too expensive. Another option for creating the subset database wouldn have been to use Jailer. I should note that we didn't have a need to mask any sensitive data.
Note. I would think this a fairly common problem so if new tools and solutions arise, please post them here as answers.
I have noticed there's no datasource for Oracle in CakePHP 2.0 for the moment, although it seems they are working on in it now: http://ask.cakephp.org/questions/view/any_news_about_oracle_datasource_with_cakephp_2_0
There are some people explaining how to use an Oracle DB adapting some code from CakePHP 1.3:
http://www.hassanbakar.com/2012/01/09/using-oracle-in-cakephp-2-0/
http://liamgraham.wordpress.com/2007/04/19/using-oracle-with-cakephp-15-minute-blog-tutorial/
But I'm not sure that's the correct way. If it was so simple, they would have released the feature already for CakePHP 2.X...
Would I have any trouble using that "cheat"?
I want to connect CakePHP with PL/SQL procedures and a desktop application and they are working over Oracle. I can not change that.
After asking some CakePHP developers I came out with the conclusion that it is not possible to use an Oracle Database with CakePHP 2.3 if you want to make a proper use of CakePHP Models and their query syntax. There's no yet available any driver for Oracle in CakePHP which is completely functional.
Therefore, the solution I found was to use the OCI8 Functions of PHP.
Like this i could use oci_parse to directly query against the DB or rather call a PL-SQL procedure which is what I finally decided to do. (because of the sql functions complexity and the division of task inside my work group)
Now, I can not make use of many of the advantages of using CakePHP models, but It was the only way.
There is a new CakePHP 3 Driver for Oracle Database released (MIT) and working with Oracle 11g and Oracle 12c databases. Some features:
Triggers
Sequences
Cursors
Stored procedures
Packages
All the basic CRUD features to allow select/insert/update/delete rows.
CakePHP Pagination
CakePHP Bake code generation
Check the Documentation here, and the release announcement here.
I have 2 databases, Oracle and SQlite. And I want to create exact copies of some of the Oracle tables in SQLite in one of my applications. Most of these tables contains more than 10,000 rows so copying each table by going through each row programmatically is not efficient. Also the table structure may change in the future so I want to achieve this using a generic way without hard-coding the SQL statements. Is there a any way to do this?
p.s. - This application is being developed using Qt framework. All the queries and databases are represented by QtSql module objects.
Can't help with Qt framework, but for large amounts of data is is usually better to use bulk-copy operations.
Export data from Oracle
http://download.oracle.com/docs/cd/B25329_01/doc/admin.102/b25107/impexp.htm#BCEGAFAB
Import data into SQLite
http://www.sqlite.org/cvstrac/wiki?p=ImportingFiles
IHTH
What you probably really want to use is the Oracle Database Mobile Server, which can automatically synchronize a SQLite and an Oracle Database.
The recent release of the Oracle Database Mobile Server (formally called Oracle Database Lite Mobile Server) supports synchronization between an Oracle Database and a SQLite or a Berkeley DB database running on the client. It supports both synchronous and asynchronous data exchange, as well as secure communications between client and server. You can configure the Mobile Server to synchronize based on several options without the need to modify the application that is accessing the database.
You can also find an excellent discussion forum for questions from developers and implementers using the Mobile Server.