Package gavo :: Package adql :: Module common

Module common

Exceptions and helper functions for ADQL processing.

Classes
	Error A base class for the exceptions from this module.
	NotImplementedError is raised for features we don't (yet) support.
	ColumnNotFound is raised if a column name cannot be resolved.
	TableNotFound is raised when a table name cannot be resolved.
	MorphError is raised when the expectations of the to-ADQL morphers are violated.
	AmbiguousColumn is raised if a column name matches more than one column in a compound query.
	NoChild is raised if a node is asked for a non-existing child.
	MoreThanOneChild is raised if a node is asked for a unique child but has more than one.
	BadKeywords is raised when an ADQL node is constructed with bad keywords.
	UfuncError is raised if something is wrong with a call to a user defined function.
	GeometryError is raised if something is wrong with a geometry.
	RegionError is raised if a region specification is in some way bad.
	FlattenError is raised when something cannot be flattened.
	IncompatibleTables is raised when the operands of a set operation are not deemed compatible.
	Absent is a sentinel to pass as default to nodes.getChildOfType.
	FieldInfoGetter An abstract method to retrieve table metadata.

Functions

getUniqueMatch(matches, colName)
returns the only item of matches if there is exactly one, raises an appropriate exception if not.

source code

computeCommonColumns(tableNode)
returns a set of column names that only occur once in the result table.

source code

Variables
	__package__ = `'gavo.adql'`

Function Details

returns a set of column names that only occur once in the result table.

For a natural join, that's all column names occurring in all tables, for a USING join, that's all names occurring in USING, else it's an empty set.