Example: Function Processing with Variable Substitution for Input Tables and Parameters - Teradata Database - Teradata Vantage NewSQL Engine

SQL Data Manipulation Language

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Published
March 2019
Language
English (United States)
Last Update
2019-05-03
dita:mapPath
fbo1512081269404.ditamap
dita:ditavalPath
TD_DBS_16_20_Update1.ditaval
dita:id
B035-1146
lifecycle
previous
Product Category
Teradata Vantage™

The function mapping definition usr_AllPairsShortestPath specifies variables for input tables and parameters.

CREATE FUNCTION MAPPING usr_AllPairsShortestPath
FOR AllPairsShortestPath SERVER TD_SERVER_DB.coprocessor
USING
vertices(vertex) IN TABLE ,
edges(edge) IN TABLE ,
sources(source) IN TABLE ,
targets(trgt) IN TABLE ,
TargetKey(GroupColumn) ,
EdgeWeight('calls') ,
MaxDistance(Distance) ,
Directed ,GroupSize ,SequenceInputBy;

The SELECT statement specifies values for the variables Distance and GroupColumn.

SELECT * FROM usr_AllPairsShortestPath (
ON callers AS vertices PARTITION BY callerid
ON calls AS edges PARTITION BY callerfrom
USING
GroupColumn ('callerto')
Distance ('-1')
) as dt ORDER BY source, target;

Upon submittal, the query is rewritten as follows. Per the mapping definition, TargetKey is substituted for GroupColumnquery and MaxDistance is substituted for Distance. EdgeWeight is also included because the mapping definition specifies a default value for this parameter.

SELECT * FROM AllPairsShortestPath (
ON callers AS vertices PARTITION BY callerid
ON calls AS edges PARTITION BY callerfrom
TargetKey ('callerto')
EdgeWeight ('calls')
MaxDistance ('-1')
) ORDER BY source, target;