Hello,
I have some questions on the explicit definition on how the result rows
are returned in the query API:
1. In the example at
https://www.openehr.org/releases/ITS/Release-0.9.0/docs/query.html#header-resultset-example
there is one result row with one fact for each of the columns that were
requested. Three of the columns contain primitves (i.e. Strings) but one
column contains a JSON representation of an object. It is difficult to
grasp from the example why some facts are returned as primitves and some
as serialized JSON objects. It would be beneficial to see the
corresponding archetype definitions in order to understand how different
columns containing different parts of the archetypes are encoded.
2. When one of the columns contains a list of items in each cell
(because the denoted data type is an ITEM_LIST), will the content of
that cell be JSON serialized ? When a user requests all laboratory
values (e.g. calcium measurements) for a specific patient, then a table
would be returned. But instead of receiving the individual measurements
in seperate columns so the result could be immediately processed in
tools like Excel or SPSS, the data would have to be again crunched by
another tool that makes a real table out of the table-JSON-compound.
2b. What happens when multiple columns can contain multiple values as
their values. When every column containing multiple values (ITEM_LISTs)
will be encoded with JSON and written to the same cell this will not be
an issue. But when the multiple values are instead distributed over
multiple cells (or rows) some mechanism has to be defined how to cope
with the combination of two columns containing multiple values for one
record. In SQL-JOINs this is handled with the Cartesian product of the
sets of facts. But this bears the risk of combinatorial explosions when
defining queries with too many columns containing too many values for
each record.
Greetings
Georg
--
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Dipl.-Inf. Georg Fette Raum: B001
Universität Würzburg Tel.: +49-(0)931-31-85516
Am Hubland Fax.: +49-(0)931-31-86732
97074 Würzburg mail: [email protected]
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