1>From a data storage point of view ,one may think of a sensor network as a distributed database that
a; collects physical measurements about the environment b; indexes them
c; serves queries from users and other applications external to or from within the network Ans; __________ (a/b/c/all)
2>The advantage of the database approach is that it provides a separation between the logical view of the data held by the sensor network and the actual implementation of these operations on the physical network (true/false)__________
3>In a classical DBMS ,data is stored in a__________ location (centralized/distributed)
4>The structure and constraints of the data format are called database__________ (table/schema) 5>The database scheme are typically defined or modified by a database administrator using __________ (DML/DDL)
6>DDL stands for___________
7>Today most databases employ relational schemas and their variants, organizing data into tables whose_____ are record tuples and whose______ are labeled by data attributes rows/columns) 8>___________compiler translates the definitions into metadata which is stored in permanent storage along with the actual data (DML/DDL)
9>___________is a data structure describing the structure of the database data and the constraints they must satisfy (metadata/temporal data)
10>In a typical database system ,the___________ directly controls storage devices such as disks and the flow of data between them and main memory (storage & buffer manager/transaction manager )
11>The database is updated through units of work named___________ (transition/transaction) 12>It is the job of the__________ to guarantee that transactions are executed atomically and in apparent isolation from other transactions (storage & buffer manager/transaction manager)
13>A user queries the database in a high level logical query language such as___________
(Oracle/SQL)
14>A query is parsed by the_____ and translated into an optimized execution plan ,which is then processed by the______ to answer the user query (execution engine/query processor)
15>In any database system, there are trade offs between the speed of answering queries and the speed of performing database updates (true/false)___________
16>In__________ database systems ,data storage may be allocated among several geographical separated locations ,connected by a communications network (centralized/distributed)
17>___________database makes the job of the query processor significantly harder (centralized/distributed)
18>Most query execution plans can be represented as trees where the_____ represent database operators and the______ correspond to producer-consumer relationships among operators (centralized/distributed)
19>P2P Stands for___________
20>In___________ networks ,active processors can number in the tens to hundreds of thousands and may come on the network and go off the network at arbitrary times (P2P/PPP)
21>Another recent trend in database systems is to consider systems for data streams. Such systems are aimed at handling long running___________ queries such as may arise in network or traffic monitoring ,telecom call ,stock market transaction or web log record summarization (continuous/discontinuous)
22>Each sensor in a sensor network takes___________ measurements of physical phenomena such as heat, sound, light ,pressure or motion (time sequenced/time stamped)
23>The issue of where to store the data becomes of paramount importance since_____
dominates______ (energy landscape/communication cost)
24>Following approaches can be used for implementing databases to support sensor network
a; transfer all the data to one or a small number of external warehouses ,where traditional DBMS system could be deployed
b; store the data within the network itself and allow queries to be injected anywhere in the network Ans; ___________ (a/b/both)
25>At the physical level, there are following major distinguishing characteristics of sensor networks when it comes to database implementation
a; the network replaces the storage and buffer manager--data transfers are from data held in node memory as opposed to data blocks on disk
b; node memory is limited by cost and energy considerations Ans; ___________ (a/b/both)
26>Following are challenges in sensor network databases a; the system as a whole is highly volatile
b; relational tables are not static since new data is continuously being sensed
c; the high energy cost of communication encourages in-networking processing during query execution
d; access to data may be hampered by arbitrarily long delays and the rates at which input data arrives to a database operator can be highly variable
Ans; ___________ (a/b/c/d/all)
27>Following are challenges in sensor network databases
a; limited storage on nodes and high communication costs imply that older data has to be discarded b; sensor tasking interacts in numerous ways with the sensor database system
c; classical metrics of database system performance ,such as throughput or delay may have to be adjusted in the sensor network context because of high variance in these quantities
Ans; ___________ (a/b/c/all)
28>Following are differences between sensor network data and those of other databases at the logical level
a; sensor network data consists of measurements from the physical world
b; additional operators have to be added to the query language to specify durations and sampling rates for the data to be acquired
c; while single shot queries are possible and useful in sensor networks ,we expect that a good fraction of the queries will be of the continuous ,long running type such as monitoring the average temperature in a room
d; it is important to have operators for correlating sensor readings and comparing them with past statistics
Ans; ___________ (a/b/c/d/all)
29>Sensor network differs from__________ networks in that nodes operate with limited energy ,processing and memory resources (data streams/P2P)
30>Sensor network differs from ___________networks in that geographic location can be of great importance in deciding what information to store and what information to query for (data streams/P2P)
31>It is advantageous to express queries to a sensor network database at a logical, declarative level ,using relational languages such as SQL (rue/false)___________
32>In querying the physical environment ,___________level interfaces allow nonexpert users to easily interact with the database (low/high)
33>_____clause specifies the period during which data is to be collected, and the______ clause specifies the frequency at which the query results are returned (sampling period/duration)
34>There may be____ queries such as the report results over an extended time window ,___queries concerning the data in the network at a given point in time and____ queries that ask for aggregate information over historical data (snapshot/historical/continuous)
35>The queries on sensor networks may
a; aggregate data over a group of sensors or a time window
b; contain conditions restricting the set of sensors from contributing data c; correlate data from different sensors
d; trigger data collection or signal processing on sensor nodes e; spawn subqueries as necessary
Ans; ___________ (a/b/c/d/e/all)
36>Not all users of a database system will be human operators (T/F)___. Programs running on the nodes themselves may generate queries in order to decide what sensing actions a node should take (T/F)___
37>___________sensor network database system maintains an SQL-type query interface for users at a front end server connected to a sensor network (courage/cougar)
38>Distributed query execution is optimized for___________ (resource usage/reaction time/both) 39>Cougar represents each type of sensor in a network as an___________ ,as in most modern object-relational databases (ASN/ADT)
40>In Cougar database ,___________provides controlled access to encapsulated data through a well defined set of access functions (ASN/ADT)
41>An ADT object in the Cougar database corresponds to a___________ sensor in the real world (logical/physical)
42>STFT stands for___________
43>The public interface of a seismic sensor ADT can comprise signal processing functions such as a; STFT
b; vibration signature analysis Ans; ___________ (a/b/both)
44>___________relations are relations that are not actually materialized as ordinary table (base/virtual)
45>Cougar introduces_____ relations in contrast to the______ relations defined in the database schema (base/virtual )
46>Cougar considers___________ query processing in the network (centralized/distributed)
47>Sensor data invariably contains measurement uncertainty due to ___________ (device noise/environmental perturbation/either)
48>GADT stands for___________
49>___________models the uncertainty as a continuous probability distribution function over possible measurement values (ADT/GADT)
50>An operation named___________ primitive allow for probabilistic equality tests ,so one can meaningfully compare different Gaussian variables (Prob/Conf/Diff)
51>Range queries are another important class of sensor network queries (true/false)___________
52>In the___________ warehousing approach ,each sensor forwards its data to a central server or warehouse connected to the network via an access point (centralized/decentralized)
53>Following are disadvantages of centralized warehousing
a; the nodes near the distinct point become traffic hot spots and central points of failure plus they may be depleted of energy prematurely
b; this approach does not take advantage of in-network aggregation of data to reduce the communication load when only aggregate data needs to be reported
c; sampling rates have to be set to be the highest that might be needed for any potential query ,possibly further burdening the network with unnecessary traffic
d; customers of the data may be other applications running on nodes themselves in the network Ans; ___________ (a/b/c/d/all)
54>In___________ approach, the data is stored within the network (centralized warehouse/in-network storage)
55>At the center of the___________ design is the appropriate choice of storage points for the data ,which act as rendezvous points between data and queries ,so that the overhead to store and access the data is minimized and the overall load is balanced across the network (centralized warehouse/in-network storage)
56>Features of the in-network storage
a; allows data to be aggregated before it is sent to an external query b; takes advantage of locality of information for in-network queries c; load-balances the database costs across the nodes
Ans; ___________ (a/b/c/all)
57>Following metrics can be used for general database systems a; network usage b; preprocessing time c; storage space requirement d; query time
e; throughput f; update & maintenance cost Ans; ___________ (a/b/c/d/e/f/all)
58>Match the following
network usage; the time taken to construct an index preprocessing time; the storage for the data and index
storage space requirement; the time taken to process a query ,assemble an answer ,and return this answer
query time; the average number of queries processed per unit of time
throughput; costs such as processing sensor data ,insertions ,dejections or repairs when nodes fail update & maintenance cost; it is characterized by total usage and hot spot usage
59>Network usage is characterized by______ which refers to the total number of packets sent in the network and_____ which refers to the maximal number of packets processed by any particular node (hot spot usage/total usage)
60>A sensor network database differs from a traditional centralized system in that a ; resources are severely constrained
b; query processing is tightly coupled with networking and application semantics Ans; ___________ (a/b/both)
61>When designing a sensor database, we desire he following properties a; persistence
b; consistency
c; controlled access to data d; scalability in network size e; load balancing
f; topological generality
Ans; ___________ (a/b/c/d/e/f/all) 62>Match the following
Persistence; the database architecture should work well on a broad range of network topologies Consistency; as the number of nodes increases ,the system's total storage capacity should increase Controlled access to data; a query must be routed correctly to a node where the data are currently stored
Scalability in network size; data stored in the system must remain available to queries, despite sensor node failures and changes in the network topology
Load balancing; different update operations must not undo one another's work ,and queries must always see a valid state of the database
Topological generality; storage should not unduly burden any one node nor should any node become a concentration point of communication
63>In-network query processing can be used to provide substantial energy savings when serving aggregate queries. This saving is possible because
a; separating data at intermediate nodes reduces the overall number of messages the network has to transmit ,thus reducing communication and prolonging the lifetime of the network
b; combining data at intermediate nodes reduces the overall number of messages the network has to transmit ,thus reducing communication and prolonging the lifetime of the network
Ans; ___________ (a/b/both)
64>In the___________ based approach ,the aggregation occurs at an external server ,each sensor sends its data directly to the server (client/server)
65>In-network aggregation and query processing typically involve___________ (query propagation/data aggregation/both)
66>A key challenge for in-network aggregation is the design of an optimal data aggregation schedule that is___________ efficient (energy/time/both)
67>___________provides an SQL-style declarative query interface, and implement aggregation mechanisms that are sensitive to resource constraints and loopy communication (TinyOS/TinyOS) 68>TinyDB supports following SQL operators
a; count b; min c; max d; sum e; average
Ans; ___________ (a/b/c/d/e/all)
69>TinyDB supports following extensions___________ (median/histogram/both)
70>For______ operator, it can be shown that the size of the partial state record is proportional to the size of the data set it summarizes ,while in_____ operator ,the size correlates with statistical properties (median/histogram)
71>___________are distributive ,meaning the size of an intermediate state is the same as that of the final aggregate__________ is algebraic in that the partial state records are not themselves aggregates for the data set ,but are of constant size (max/min/count/average/sum)
72>_____is holistic and______ is content sensitive (median/histogram)
73>The performance of TinyDB is___________ related to the amount of intermediate state information required per aggregate (directly/inversely)
74>TinyDB uses ___________ based mechanism for data aggregation (emoge/epoch) 75>TinyDB builds a___________ tree for aggregation (static/dynamic)
76>In the query tree ,_____are the operators and______ are data dependencies among the operators (nodes/edges)
77>The task assignment problem is___________ complete (NP/PN)
78>A tree based query propagation mechanism is appropriate for a ___________based application (client/server)
79>DCS stands for___________
80>____________is a method proposed to support queries from any node in the network by providing a rendezvous mechanism for data and queries that avoids flooding the entire network (DCE/DCS)
81>Directed diffusion is an example of data centric routing (true/false)___________
82>At the center of a DCS system are___________ points ,where data and queries meet (rendezvous/meeting)
83>GHT stands for___________
84>An instance of DCS is the ___________ (GLS/GHT)
85>in___________ ,the translation from node attributes to storage location is accomplished by a hash function ,which attempts to distribute data evenly across the network (GLS/GHT)
86>___________may be regarded as a variant of publish and subscribe except the event broker serves as the data storage and rendezvous point (DCS/DCE)
87>A type of query that is especially appropriate for sensor network databases is a __________query (range/boundary)
88>In___________ query ,a certain range is specified for a number of attributes of interest on the data sought (range/boundary)
89>In general ,sensor network data is multi-attribute (true/false)___________
90>__________is aimed at point queries or exact matches, so it is not well suited for queries involving data ranges (GLS/GHT)_
91>in general ,the complexity of answering a query in a sensor network will be a function of a; the size of the data in the network
b; the number of records returned Ans; ___________ (a/b/both)
92>Following are classical measures of the quality of an index___________ (speed/size/both) 93>The ___________data the index stores ,the faster the query processing can be (less/more) 94>wrt one dimensional indices ,the particular subsets of data forming the prestored answers are referred to as the___________ subsets (orthogonal range/canonical)
95>In canonical subsets of sensors along a road ,an___________ node in the tree aggregates information from all its descendant sensors in th tree (internal/external)
96>Partial data aggregation is a key feature of any indexing scheme for range searching (true/false)___________
97>When we have a set of attributes each parameterized by a scalar value and query with a interval along a subset of the parameters ,then we call this as___________ searching (orthogonal range/canonical)
98>Examples of hashing/partitioning schemes are___________ (grid files/partitioned hashing/both) 99>Examples of tree based index structure include
a; multilevel indices b; k-d trees c; quad tree d; R trees Ans; ___________ (a/b/c/d/all)
100>The storage cost for storing m events into ___________is O (m) {k-d tree/multi level}
101>Range searching indices provide a hierarchical summarization of records or events in the database according to simple attributes of interest (true/false)__________
102>Wavelet transforms provide one way to compress and summarize information for both temporal and spatial signals ,and are widely used in__________ processing (signal/image/both)
103>__________is a system that provides multi-resolution storage and search for sensor data (DIAMETERS/DIMENSIONS)
104>DIFS stands for__________
105>If we can partition aggregated data in a meaningful way, then we can distribute that data over several nodes in the network and thus lessen the load on nodes near the hierarchy root. A system that has developed this approach is__________ (DIPS/DIFS)
106>__________uses a modified GHT to find an index node (DIPS/DIFS)
107>The idea of storing information locally is at the heart of the__________ approach to storing data in a sensor network (fractional cascading/locality preserving hashing)
108>The key idea of the_________ approach is to store at each sensor information about data available elsewhere in the network ,but in such a way that a sensor knows only a fraction of the information from distant parts of the network (fractional cascading/locality preserving hashing) 109>Fractional cascading accomplishes following goals simultaneously
a; the total amount of information duplication across all sensors is kept small because of the geometric decrease with distance
b; the communication costs required to build this index and its update cost remain reasonable ,as on a the average information travels only short distances
c; neighboring sensors have highly correlated world views ,this allows for smooth information gradients and enables local search algorithms to work well
Ans; __________ (a/b/c/all) 110>DIM stands for__________
111>__________approach is developed in the DIM system (fractional cascading/locality preserving hashing)
112>In__________ approach ,we map the attribute space to the plane so that nearby locations in attribute space correspond to nearby locations in the plane (fractional cascading/locality preserving hashing)
113>The key idea of __________is a clever construction of a locality preserving mapping between the multidimensional attribute space and the spatial domain of sensors (DIM/DIFS)
114>_____databases has to store static information while_____ databases must deal with continuous data acquisition and allow the temporal aspects of the data to be used in queries (traditional/sensor network)
115>The sensor data acquired by a single node over time can be processed and summarized directly on that node ,with no additional communication costs (true/false)___________
116>One of disadvantage of sensor network is that overall node storage is very limited (true/false)__________
117>The__________ system computes multi-resolution summaries of data (DIAMETERS/DIMENMSIONS)
118>__________is a monotonically decreasing function specifying acceptable query response accuracy as a function of data age (mining function/aging function)
119>KDS stands fo___________120>wrt indexing motion data, in __________setting ,the correctness of the index is certified by certain atomic predicates called certificates ,on the parameters defining the index (KDC/KDS)
121>__________approach incrementally tracks the index structure as objects move and can be used to answer queries about the current state of the world (KDC/KDS)
122>Following are general approaches to indexing motion data a; using time oblivious approach
b; using KDS approach Ans; __________ (a/b/both) ANSWERS
1>all 2>T
3>centralized
4>schema 5>DDL
6>Data Definition Language 7>row, column
8>DDL 9>metadata
10>storage & buffer manager 11>transaction
12>transaction manager 13>SQL
14>query processor, execution engine 15>T
16>distributed 17>distributed 18>node, edge 19>peer to peer 20>P2P
21>continuous 22>time-stamped
23>communication costs, energy landscape 24>both
25>both 26>all 27>all 28>all
29>data streams 30>P2P
31>T 32>high
33>duration, sampling period 34>continuous, snapshot, historical 35>all
36>T,T 37>cougar 38>both 39>ADT 40>ADT 41>physical
42>Short Time Fourier Transform 43>both
44>virtual 45>virtual, base 46>distributed 47>either
48>Gaussian ADT 49>GADT
50>diff 51>T
52>centralized 53>all
54>in-network storage 55>in-network storage 56>all
57>all
58>1-f 2-a 3-b 4-c 5-d 6-e
58>1-f 2-a 3-b 4-c 5-d 6-e