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@ -957,7 +957,7 @@
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- DONE Review relational algebra https://www.geeksforgeeks.org/introduction-of-relational-algebra-in-dbms/
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- LATER review lab2
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- LATER SQL join
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- LATER Block 2
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- DONE Block 2
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- DONE EER
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- Most useful additional concept of EER model:
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specialization/generalization.
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@ -1005,7 +1005,10 @@
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- The instances of a potential subclass participate in a relationship unique to that subclass.
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- DONE Block 3
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- DONE DB transaction management
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- LATER anomalies
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- NOW anomalies
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:LOGBOOK:
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CLOCK: [2023-06-14 Wed 16:41:52]
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:END:
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- DONE Deadlock and how it can be resolved. #flashcard
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- A deadlock is a situation in which two or more transactions are unable
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to proceed because each is waiting for a resource held by the other,
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@ -1073,31 +1076,24 @@
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- Boyce-Codd Normal Form (BCNF): BCNF is a stricter form of 3NF that ensures that each determinant in a table is a candidate key. In other words, BCNF ensures that _each non-key attribute is dependent only on the candidate key._
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- Fourth Normal Form (4NF): 4NF is a further refinement of BCNF that ensures that _a table does not contain any multi-valued dependencies._
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- Fifth Normal Form (5NF): 5NF is the highest level of normalization and involves decomposing a table into smaller tables to _remove data redundancy and improve data integrity._
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- DONE Block 4
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- LATER Block 4
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- DONE Distributed DBMS
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collapsed:: true
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- DONE client server arch
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collapsed:: true
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- Computers (client) connected over wired or wireless local area network (LAN)
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- The database itself and the DBMS are stored on a central device called the database server, which is also connected to the network.
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- Distributed Database
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collapsed:: true
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- A logically interrelated collection of shared data (and a description of this data), physically spread over a computer network.
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- Distributed DBMS
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collapsed:: true
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- Software system that permits the management of the distributed database and makes the distribution transparent to users.
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- the key issues
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collapsed:: true
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- Fragmentation
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- Allocation
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- Replication
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- importance and different types of fragmentation
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collapsed:: true
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- Horizontal
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- Vertical
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- Mixed
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- different types of transparency
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collapsed:: true
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- Distribution Transparency: The database feels as a single, logical entity
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- Transaction Transparency: Ensures that all distributed transactions maintain distributed database’s integrity and consistency.
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- Performance Transparency: must perform as if it were a centralized DBMS.
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@ -1125,54 +1121,41 @@
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- XSD: a more comprehensive method of defining content model of
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an XML document.
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- DONE Data Mining
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collapsed:: true
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- concept
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collapsed:: true
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- The process of extracting valid, previously unknown, comprehensible,
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and actionable information from large databases and using it to make
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crucial business decisions.
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- different applications
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collapsed:: true
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- Retail / Marketing
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- Banking
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- Insurance
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- Medicine
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- basic techniques
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collapsed:: true
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- predictive modelling,
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collapsed:: true
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- uses observations to form a model of the important characteristics of some
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phenomenon
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- database segmentation,
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collapsed:: true
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- Uses unsupervised learning to discover homogeneous subpopulations in a database to improve the accuracy of the profiles.
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- link analysis,
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collapsed:: true
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- Establishing links, called associations, between the individual
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records, or sets of records, in a database.
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- deviation detection.
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collapsed:: true
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- Identifies outliers, which express deviation from some previously
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known expectation and norm.
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- DONE NoSQL
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collapsed:: true
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- the motivation for NoSQL
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collapsed:: true
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- By giving up ACID constraints, one can achieve
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much higher performance and scalability.
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- explain the concepts of NoSQL
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collapsed:: true
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- NoSQL databases (aka "not only SQL") are non-tabular databases and store
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data differently than relational tables. NoSQL databases come in a
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variety of types based on their data model. The main types are document,
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key-value, wide-column, and graph. They provide flexible schemas and
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scale easily with large amounts of data and high user loads.
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- explain the application areas of NoSQL
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collapsed:: true
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- NoSQL is an alternative, non-traditional DB technology to be
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used in large scale environments where (ACID) transactions are not a priority.
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- CAP theorem:
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collapsed:: true
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- There are 3 main properties for distributed management:
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1. Consistency → A data item has the same value at the same time (to
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ensure coherency).
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