org.apache.calcite.rel.metadata

Interface BuiltInMetadata.Size

All Superinterfaces:

Metadata

Enclosing class:

BuiltInMetadata

public static interface BuiltInMetadata.Size
extends Metadata

Metadata about the size of rows and columns.

Method Summary

Methods

Modifier and Type	Method and Description
List<Double>	averageColumnSizes() Determines the average size (in bytes) of a value of a column in this relational expression.
Double	averageRowSize() Determines the average size (in bytes) of a row from this relational expression.

Methods inherited from interface org.apache.calcite.rel.metadata.Metadata

rel

Method Detail

averageRowSize

Double averageRowSize()

Determines the average size (in bytes) of a row from this relational expression.

Returns:

average size of a row, in bytes, or null if not known

averageColumnSizes

List<Double> averageColumnSizes()

Determines the average size (in bytes) of a value of a column in this relational expression.

Null values are included (presumably they occupy close to 0 bytes).

It is left to the caller to decide whether the size is the compressed size, the uncompressed size, or memory allocation when the value is wrapped in an object in the Java heap. The uncompressed size is probably a good compromise.

Returns:

an immutable list containing, for each column, the average size of a column value, in bytes. Each value or the entire list may be null if the metadata is not available