cognos ds fact build 中duplicate key和key的概念

博客介绍了fact buile properties中可设置重复键处理方式,键为参考维度用于过滤数据。还提到table delivery properties中的键涉及数据更新策略,选insert/update时参考key值,未设置则默认参考维度主键,同时表示对index和replace概念存疑。

在fact buile properties中可以设置duplicate key handling可以设置允许,拒绝和合并重复键,这里的键指的是参考维度,它来负责过滤数据。

对于table delivery properties中的key指的是对于数据的更新策略,如果选择insert/update则参考key的值,如果目标库中有输入数据对应的key则update否则insert。如果这里没有设置key,则默认key的就是参考维度的主键。这里的index的概念还是不明白, 更新策略中的replace的概念和用途不明白是什么含义,欢迎指教!

### Drois Duplicate Issue in Android Development In addressing the concern about duplicates or replicas related to Drois within Android development, it is important to understand how databases handle concurrent operations such as reading and writing without causing conflicts or duplications. In systems like Oracle Database, mechanisms are implemented to ensure that writers of database data do not wait for readers of the same data[^1]. However, this principle applies broadly across various types of applications including those developed on Android platforms. For handling potential duplication issues specifically with Drois (assuming a typo meant DROI which could refer to Data Replication Object Identifier), developers should focus on implementing unique constraints at both application level code and database schema design: #### Application Level Code Implementation To prevent duplicate entries programmatically during runtime: ```java // Check if an entry already exists before inserting new one. public boolean checkDuplicate(String droiId) { SQLiteDatabase db = getWritableDatabase(); Cursor cursor = db.query( "drois_table", new String[] {"id"}, "droi_id=?", new String[]{droiId}, null, null, null); boolean hasDuplicates = cursor.getCount() > 0; cursor.close(); return hasDuplicates; } ``` If `checkDuplicate` returns true, indicating there's already an existing record matching provided identifier (`droiId`), insertion can be skipped thus avoiding creation of unnecessary copies. #### Database Schema Design Consideration At the time of designing tables where these objects will reside, enforce uniqueness through SQL commands when creating table structure: ```sql CREATE TABLE IF NOT EXISTS drois ( id INTEGER PRIMARY KEY AUTOINCREMENT, droi_id TEXT UNIQUE NOT NULL, other_columns... ); ``` By declaring column(s) as `UNIQUE`, any attempt made by application logic to insert records violating this constraint would fail gracefully preventing accidental replication. --related questions-- 1. How does enforcing unique constraints impact performance in large-scale Android apps? 2. What strategies exist for efficiently managing synchronization between local SQLite databases and remote servers while minimizing risk of duplication? 3. Can you provide examples demonstrating best practices for error handling around failed inserts due to violation of unique key constraints? 4. Are there specific libraries recommended for simplifying management of object identifiers within mobile applications?
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