View maintaining anomaly analysis under concurrent updating environment 并發(fā)更新環(huán)境下的視圖維護異常研究
This property should be set to false in concurrent update scenarios as deadlocks may occur in these scenarios 在并發(fā)更新的情況下,這一屬性應(yīng)該設(shè)置為false ,因為在這些情況下可能出現(xiàn)死鎖。
Typically , online index operations will be slower than equivalent offline index operations regardless of the concurrent update activity level 通常,無論并發(fā)更新活動的級別如何,聯(lián)機索引操作都將比相應(yīng)的脫機索引操作更慢。
It would be nice if there were a finer - grained mechanism for reliably managing concurrent updates to individual variables ; and on most modern processors , there is 如果有更細粒度的機制來可靠管理對單獨變量的并發(fā)更新,則會更好一些;在大多數(shù)現(xiàn)代處理器都有這種機制。
This paper decomposes materialized views maintenance into ods / db interface and dw / ods interface . multiple data sources with concurrent updates may result in update anomalies of the materialized views . so at ods / db interface this paper introduces an improved nested transaction model - based transaction concurrency control mechanism to maintenance views in ods on line 本文把視圖的一致性維護問題分解到三層結(jié)構(gòu)的ods / dw和dw / ods兩個接口上分別實現(xiàn),并且引入視圖生成樹的概念,在ods / db接口處采用基于改進嵌套事務(wù)模型的并發(fā)控制機制,聯(lián)機維護ods的數(shù)據(jù),大大提高了視圖維護過程中的并發(fā)度和靈活性。