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Distributed DB > chapter 2 > Flashcards

chapter 2 Flashcards

1
Q

Give an overview for The architecture of a system?

A
  • outlines its structure, components, their functions, and interactions.
  • It involves specifying modules, interfaces, and interrelationships in terms of data within the system
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2
Q

What is A Reference Architecture?

A
  • Are developed by standard developers, to define standardized interfaces based on goals and context
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3
Q

What are the Three “reference” architectures for a distributed DBMS?

A
  1. client/server systems,
  2. peer-to-peer distributed DBMS,
  3. and multi-database systems.
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4
Q

What is the ANSI/SPARC architecture?

A
  • Are the efforts of the Standards Planning and Requirements Committee (SPARC), that determine which aspects of database management systems should be standardized, if feasible
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5
Q

ANSI/SPARC architecture is a ______ approach to defining the architecture of a DBMS?

A

data logical

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6
Q

What is the focus of the ANSI/SPARC architecture?

A

it focuses on the different user classes and roles and their varying views on data.

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7
Q

What are the 3 levels / schemas of the ANSI/SPARC architecture?

A
  1. External Schema (User View)
  2. Conceptual Schema (Community View)
  3. Internal Schema (Physical View)
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8
Q

Explain the External Schema (User View)?

A
  • IS the way data is viewed by individual users or groups of users.
  • Defines how different user classes or roles perceive the data they are interested in.
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9
Q

Explain the Conceptual Schema (Community View)?

A

It provides an abstract and high-level view of the entire database, independent of the specific details of how data is stored or accessed.

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10
Q

Explain the Internal Schema (Physical View)?

A
  • Is the physical implementation of the database on the storage media.
  • It defines how data is stored, indexed, and organized.
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11
Q

The separation of the external schemas from the conceptual schema enables _______ ?

A

logical data independence

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12
Q

The separation of the conceptual schema from the internal schema allows _______ ?

A

physical data independence

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13
Q

query processing, can be time-consuming, especially for complex queries.

A

True

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14
Q

SQL query itself specifies what data is needed, and specifies the optimal strategy for retrieving that data.

A

False
- it does not dictate the optimal strategy

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15
Q

What are the three key characteristics to classify the architecture schema of a DDBMS?

A

(1) the autonomy of local systems
(2) their distribution, and
(3) their heterogeneity

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16
Q

________ is the degree to which individual DBMSs can operate independently?

A

Autonomy

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17
Q

What are the Requirements of an autonomous system?

A
  • Local operations of individual DBMSs remain unaffected by their participation in the distributed system.
  • The processing of queries by individual DBMSs should not be influenced by the execution of global queries accessing multiple databases.
  • System consistency should not be compromised when individual DBMSs join or leave the distributed system.
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18
Q

What are Three Alternatives for Autonomous Systems in Distributed DBMS?

A
  1. Tight Integration
  2. Semiautonomous Systems
  3. Total Isolation
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19
Q

Explain Tight integration.

A
  • Single-image of the entire db is available, which may reside in multiple dbs.
  • From users’ POV, the data are logically integrated in one database.
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20
Q

data managers are implemented in _______ ?

A
  • tightly-integrated systems so that one of them is in control of the processing of each user request
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21
Q

Describe Semiautonomous Systems?

A
  • a federation of independent DBMSs that share local data.
  • Each DBMS determines which parts of its database are accessible to users of other DBMSs.
  • Not fully autonomous because they need modifications to exchange information with each other.
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22
Q

Explain Total Isolation.

A
  • Individual systems are stand-alone DBMSs.
  • DBMSs are unaware of the existence of other DBMSs and can’t communicate with them.
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23
Q

Processing user transactions that access multiple databases is challenging in _______ ?

A

total isolation autonomy

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24
Q

autonomy is the distribution of ______ while distribution is the distribution of _____ ?

A

control , data

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25
Q

What are we considering in Distribution?

A
  • the physical distribution of data over multiple sites
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26
Q

What are the 2 approaches to distribute a DBMSs?

A
  1. client/server distribution
    ▪ data management duties at servers
  2. peer-to-peer distribution (full distribution).
    * Each machine has full DBMS functionality
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27
Q

What is Heterogeneity?

A

refers to the presence of diverse hardware, software, and network components

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28
Q

What are the Three alternative architectures?

A
  1. client/server distributed DBMSs
  2. a peer-to-peer distributed DBMS
  3. a peer-to peer distributed, heterogeneous multidatabase system
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29
Q

Explain a Client/Server Architecture?

A
  • Query processing, optimization, transaction management, and storage management are performed at the server.
  • The client handles the application, user interface, and manages cached data and transaction locks.
30
Q

What are the Types of Client/Server Architecture?

A

Multiple Client/Single Server
Multiple Client/Multiple Server

31
Q

What are the 2 Management Strategies for CSA?

A

A. Client Manages Own Connection:
Simplifies server code.
Results in a “heavy client” system.

B. Client Knows “Home Server”
Concentrates data management at servers.
Results in “light clients” with transparency provided at the server interface.

32
Q

The primary distinction between client/server systems and peer to-peer ones is in the level of transparency.

A

False
- in the architectural paradigm that is used to realize transparency.

33
Q

What are the Elements of Peer-to-Peer Architecture?

A
  1. Local Internal Schema (LIS):
    Individual internal schema definition at each site.
  2. Local Conceptual Schema (LCS):
    Describes logical organization of data at each site,
  3. Global Conceptual Schema (GCS):
    Describes enterprise-wide data view
    Supports location and replication transparencies.
  4. External Schemas (ESs):
    User applications and access to the database are supported by external schemas.
34
Q

_____ is Defined above the global conceptual schema to support user applications and user access to the database?

A

External schemas (ESs)

35
Q

_____ handles fragmentation and replication.

A

Local conceptual schema (LCS).

36
Q

_____ is the Union of local conceptual schemas.

A

Global conceptual schema (GCS)

37
Q

In Peer-2Peer the distributed DBMS translates global queries into a group of local queries

A

True
only 1 GCS to many LCS

38
Q

What are the Two basic components in P2P?

A
  • User processor [ ES, GCS ]
  • Data processor [ LCS, LIS ]
39
Q

What are User processor Components in P2P DBMS?

A
  • The user interface handler
  • The semantic data controller
  • The global query optimizer and decomposer
  • The distributed execution monitor
40
Q

_____ Interprets user commands and formats result data for users?

A

The user interface handler

41
Q

Explain the role of Semantic Data Controller?

A
  • Uses integrity constraints from the global conceptual schema to check user processing
  • Responsible for authorization
42
Q

Explain Global Query Optimizer and Decomposer?

A
  • Determines execution strategy using global and local conceptual schemas.
  • Translates global queries into local ones
43
Q

Explain Distributed Execution Monitor.

A
  • Coordinates distributed execution of user requests.
  • Aka the distributed transaction manager.
44
Q

What are Data processor Components in P2P DBMS?

A

1.The local query optimizer
2. The local recovery manager
3.The run-time support processor

45
Q

______ Acts as the access path selector in data processor?

A

The local query optimizer

46
Q

_____ Ensures local database consistency in the event of failures in the data processor?

A

The local recovery manager

47
Q

_____ Physically accesses the database based on the schedule generated by the query optimize?

A

The run-time support processor

48
Q

The local recovery manager Acts as the interface to the operating system

A

False
The run-time support processor

49
Q

Explain a Database Buffer (or Cache) Manager?

A
  • Is a component contained with in the, The run-time support processor that is responsible for maintaining the main memory buffers and managing the data accesses
50
Q

What is The fundamental difference between multi-DBMS & distributed DBMS.

A

the existence of full-fledged DBMSs, each of which manages a different database in multi-DBMS

51
Q

From the perspective of individual DBMSs, the MDBS layer is just another application that submits requests and receives responses.

A

True

52
Q

What are the 3 main Complications Introduced by Distribution?

A
  1. Replication Complexity
  2. Failure Complexity
  3. Synchronization Problem
53
Q

What must the Distributed database do to handle Replication Complexity?

A
  • Choose replica to be accessed in retrievals.
  • Ensure updates are reflected on all replicas
54
Q

What must the Distributed database do to handle Failure Complexity?

A
  • System must handle failures (hardware / software) during updates.
  • Ensure effects are reflected on data once the system recovers.
55
Q

What is Synchronization Problem?

A

The Lack of instantaneous information on actions at other sites

56
Q

What are other Complications Introduced by Distribution?

A
  • cost of replicating resources
  • managing distribution
  • devolution of control
57
Q

List the Design Issues in Distributed Database Systems.

A
  1. Distributed Database Design
  2. Distributed Directory Management
  3. Distributed Query Processing
  4. Distributed Concurrency Control
  5. Distributed Deadlock Management
  6. Reliability of Distributed DBMS
58
Q

Explain Distributed Database Design.

A
  • Data can be Partitioned (non-replicated) or replicated.

> Partitioned: Database divided into disjoint partitions at different sites.

> Replicated: Fully replicated (entire database stored at each site) or partially replicated (each partition stored at multiple, but not all, sites).

59
Q

Explain Distributed Directory Management.

A

Directory :

  • Contains information about data items in the database.
  • May be global or local to DDBS.
  • Can be centralized or distributed across sites.
  • Has Complex management.
60
Q

Explain Distributed Query Processing.

A
  • Involves designing algorithms to analyze queries and optimize their execution
  • Considers data distribution, communication costs, and lack of locally-available information.
  • Objective is to optimize performance within constraints.
61
Q

______ involves the synchronization of accesses to the distributed database, such that the integrity of the database is maintained?

A

Distributed Concurrency Control

62
Q

What is mutual consistency?

A

When multiple copies of every data item to converge to the same value

63
Q

What are the fundamental primitives used in Distributed Concurrency Control?

A

Locking
timestamping

64
Q

_______ is based on the mutual exclusion of
accesses to data items

A

Locking

65
Q

What is timestamping?

A

where the transaction executions are ordered based on timestamps

66
Q

intermediate results of a transaction should not be visible to other concurrently executing transactions

A

True

67
Q

transanaction isolation can be ensured trivially by _______ ?

A

running transactions serially(timestamp)

68
Q

What is deadlock?

A

occurs when two or more transactions are blocked indefinitely, each waiting for the other to release a lock.

69
Q

What Alternatives do we have for deadlock?

A

prevention, avoidance, detection, and recovery.

70
Q

Explain Reliability of Distributed DBMS.

A

ensure database consistency, detect failures, and recover from them.

Distributed DB (3 decks)

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