]
Steven Hawkins commented on TEIID-1819:
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No you didn't misundertand. In our metadata files for instance all records have
identifiers and we have parent records with lists of child identifiers, children with
parent identifiers, and some with 1-1 relationships. In any of those cases it is possible
to join the records after the initial extraction.
If you're basing the relationship positionally, for example B child entries occur
directly after an A parent record, then we'll need concrete examples/rules for the
file contents and the possible TEXTTABLE syntax. For example are you assuming the
presence of the selector header lines, or will the user need to specify the relevant
schema for the parent columns? Is only 1 level of relationship possible or can these
files describe multi-level hierarchies?
Alternatively is there a standard or RFC that would be a good guide?
Reading multi entity data from a single data file
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Key: TEIID-1819
URL:
https://issues.jboss.org/browse/TEIID-1819
Project: Teiid
Issue Type: Feature Request
Components: Query Engine
Affects Versions: 7.6
Environment: Any
Reporter: Peter Larsen
Assignee: Steven Hawkins
A common problem for data files is the concept of multiple data sets inclosed in the same
file. An example is a data file of accounts receivable orders. You'll export at least
two logical entities: Orders and OrderLines. Each of the two entities have very different
data sets; the relate (OrderLines belong to a particular Order) and there are a dynamic
number of OrderLines per Order.
A common way to differentiate is to put a special "record type" selector as the
first field in each record. Ie. A and B. The load program will based on this selector
apply different templates to map the columns, and it will also know that the OrderLines
are associated with the Order above it and create that relation column ID in the out put.
Example:
;selector=A,orderdate,ordernumber,customernumber,ordertotal,ordertax
;selector=B,lineno,itemno,description,quantity,priceach,pricetotal
A,10-dec-2011,12345,3322,3000,222
B,1,123,Sprockets Black,30,50,1500
B,2,333,Sprockets Blue,300,5,1500
A,11-dec-2011,12346,3311,.....
etc.
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