Structured database queries

1

1

1

No

Unstructured text searches

 2a

No

Unusual

1

Fast query responses

 2b

2

1

1

Data stays at source

 2c

1

No

 2^c

Near real-time index updates

 2d

1

Unusual

Unusual

Non-intrusive system changes

2e

1

2

1

Low impact on data source

1

3

1

1

ALL data sources – structured, unstructured, and semi-structured

1

No

No

 2f

Very large data sets

2

 3g

1

1

Merge results

1

2

1

N/A

Original schemas

1

1

No

N/A

Complex queries

2

 2^g

 2^g

 2^f

Ad hoc queries

1

 3^g

 3^g

1

Range queries

1

 3^g

 2^g

N/A

No data processing

 2h

1

3

 2

Familiarity of approach

3

1

1

2

Applications do not know about data sources

1

2

1

No

Do not need exact queries

1

2

Need

1

Drill-down to source data level

1

1

Unusual

1

No additional storage

2i

1

Significant storage

 2

High-level aggregations

 (2)j

3

1

N/A

Use data from one source to find data in another

1

No

N/A

Unusual

Data mining

 2k

No

1

N/A