Database

1. Structure of the data * Relational Model: Resembles an array of structs in C. * Semistructured Model: XML 2. Operations on the data * Relational Model: Relational algebra (SQL) * Semistructured Model: Path (e.g. n1.n2.n3.n4) 3. Constraints * Don’t see any major difference here. The semistructured model can say

* Connection: A connection is a “physical circuit”, a pathway to a database server. * Session: The SQL operations that are performed while a connection is active form a session. The session is associated with CATALOG(database) and SCHEMA. A connection can contain 0, 1 or more sessions

Paper:ARIES: a transaction recovery method supporting fine-granularity locking and partial rollbacks using write-ahead logging [http://dl.acm.org/citation.cfm?id=128770] * Redo: LSN makes sure undo is performed only once. No additional log is written during redo process. * Undo: LSN and CLR(Compensation log record) together makes sure

Difference between latches and locks > Usually, latches are used to guarantee physical consistency of data, while locks are used to assure logical consistency of data. Hierarchical locking > The intention locks (IX, IS, and SIX) are generally obtained on the higher levels of the hierarchy (e.g., table), and the S

Paper:What goes around comes around [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.113.5640] IMS Era * Physical and logical data independence are highly desirable * Tree structured data models are very restrictive * It is a challenge to provide sophisticated logical reorganizations of tree structured data * A