Metadata for Approximate Query Answering Systems

Table 1

Metadata identification.

Methodology	User-oriented metadata		System-oriented metadata
	Common	Specific
Summary table			Refresh date
Wavelet		Resolution level	Table cardinality; Column domain; Refresh date
Histogram	Data warehouse name; Reduced table name; Reduced column name	Bucket width	Table cardinality; Column domain; Number of buckets; Refresh date
Sampling		Sample size	Table cardinality; Refresh date
Orthonormal series		Approximation degree	Table cardinality; Column domain; Refresh date