Semantic Assumptions and Query Evaluation in Temporal ... - CiteSeerX

Semantic

Assumptions

Claudio

and

Bettini

X.

Query

Sean

Evaluation

Wang

in

Elisa

Temporal

Bertino

Databases*

Sushil

Jajodia

Abstract AcctHo

When

querying

certain

a temporal

semantic

This paper assumptions: based

database,

assumptions

on

a user

stored

often

makes

temporal

data.

formalizes and studies two types point-based and interval-baaed,

assumptions

include

those

of semantic The point-

assumptions

interpolation methods, while the interval-based include those that involve different temporal granularities). Each assumption certain implicit data from the database. The database system as (possibly infinite) This paper introduces

that

use

implicit data to answer user queries. a new method to facilitate such query

evaluations. A user query is translated into a system query such that the answer of this system query over the explicit

Figure

(safety

a user the that

feature

of

the

richness

in

semantics

associated

domains.

As an example,

consider

ACCOUNTS shown corresponds

in

to

an

holder

(ACCHO1),

interest

rate

values to

1.

account

relation

information with

temporal relation

Each

balance

become

valid,

entries

or a change are timestamps

of the

(month/day/year)

day

*The istered

(up

work is supported by

the

Office

NO014-92-J-4038. ing by the

George the

NSF

di

Wang

and

ware VA

Work Mason grant

Jajodia

Systems 22030.

{xywang,

Via

of

the

jajodia}@isse.

Bettini

39/41,

Department

Engineering, Emails:

Wang

George {bettini gmu.

,

grant,

Mason ebertino}Qdsi

while also

visit-

supported

Bertino

are

Milano,

Information

Italy, and

University, unimi

with

the

The

in

(deposit

the

the

amount

is

in the

the

persistence

values

or

for

balance

is less than of

whose

time

is given

persist

second

for

each

are that

at the

end

natural

that

is the

month.

occurred

for

end-of-month

In

[Sho87].)

many

are

semantic

databases

but the

last

balance

stored

July

long

realized

dis-

balance in the

1, assuming

1001 after

rea-

not

example,

for

only

assump-

For

balance

value

by the temporal

Figure

account

its

is borrowed

assumptions

in

community.

of a month

for

are

month,

that

community

There

its

each second

“liquid”

identified

is,

that

in that for

assume

semantic

quite

day

the

That

assume

is 3.00

term

reasoning

community. in

of each

we can

different

example,

as liquid.

we can

(The

assumptions

that

involve For

if its value

month,

temporal

cussed

also

a month,

a month,

that

of the

soning

the

for

may

aforementioned

tivities

and

day

is 3.00 for

no ac-

7/3/93:09:00:00,

1993

will

be $4,000.

Soft-

Researchers

Fairfax, it

time,

relation

degli

the balance

no balance

can be classified

each

tions

adminnumber

and

on

expects

she asks

granularities).

is 3.00 for

some

i.e.,

When

timestamp

(time

at the same

from

she

transaction

example

is 3.00 for

value

of each

of time

Universit~

20135 of

the

grant

is

and

rates

ACCOUNTS

performed

of

dell’Informazione,

Comelico

with

under

was

Work

of

consisting

by an ARPA

Bettini

Scienze

with

in interest

querying

Research

IRI-9409769. di

Milano,

in part Naval

University.

Dipartimento

Studi

of

When

are added

as opening

concatenated

to seconds),

AnIntRate

and

persists,

time

assumptions types

value

values

date

Semantic

the

assumptions

instance,

she searches

ACCHO1

temporal

annual when

semantic

another

whose

ACCOUNTS

number.

if its

(Time)

relation

For

balance

Another

attribute

account

a transaction,

the

the

account

No),

an account,

of Time

by

of the

is performed.

time,

transaction question.

(Acct

such

3/4/93:10:01:55 3/4/93:1 1:00:00 3/4/93:12:19:03 3/4/93:18,00:00 7/3/93:09:00:00

unless

that

in

attribute

New

4.00 3.00 2.50 3.00 4.00

at a particular

of ACCOUNTS

(Balance),

an event

3500 2000 500 1500 4000

data.

account

same

for

tup]e

occurs.

The

the

its

e), and the time

whenever

is

the temporal

number

account

(AnIntRat

in the tuple

this

Figure

3/3/93 :09!01:00

‘