Query Execution Times


Query type Description (segments and descriptors) Execution time (sec)
Text-based semantic query Keyframe (keyword) 0.125
Text-based semantic query Moving Region (keyword) 0.125
Text-based semantic query Keyframe (keyword),
Moving Region (keyword)
0.188
Color query Keyframe (CSD) 0.141
Texture query Keyframe (HTD) 0.125
Color + Texture query Keyframe (CSD+HTD) 0.172
Shape query Moving Region (RSD) 0.156
Spatial query Text-based, 2 Still Regions 0.172
Spatial query Text-based, 2 Moving Regions 0.187
Spatial query Sketch-based, 2 Moving Regions 0.187
Composite query in Figure 3.1 Keyframe (DCD+keyword),
Moving Region (CSD+RSD+keyword)
0.438
Composite query in Figure 3.2 2 Still Regions (CSD+EHD),
Moving Region (keyword)
0.391
Table 1: Query execution times (in seconds). Query Processing Server and Tamino XML database are installed on a notebook PC with Intel Core 2 dual-core 2.0 GHz processors and 2.0 GB of RAM, running Windows XP.

The query execution time is proportional to the number of subqueries (number of video segments and descriptors in the query), database size (number of video segments in the database), the sizes of the descriptors and the complexity of the matching algorithm (distance metric). Queries involving low-level descriptors take longer to execute compared to text-based queries since the distance computation between the low-level descriptors are computationally more expensive.

The multi-threaded query processing architecture provides some degree of parallelism and shortens the query execution times when the subqueries are executed in separate threads. For instance, a Keyframe query with CSD takes 0.141 seconds and a Keyframe query with HTD takes 0.125 seconds to execute, while a Keyframe query with CSD and HTD descriptors takes 0.172 seconds to execute, which is less than the serial execution times of CSD and HTD queries (0.266 seconds). This is also demonstrated in the two composite queries in the table.



Home - Contents
Last update: 03.05.2009
For questions and/or comments please contact Muhammet Baştan