TAP MAXREC interpretation

[Thomas Boch]

Hi Pierre,

I agree this behaviour is surprising ; you don't get any row back 
whereas the full result has far less rows than the service MAXREC limit.

Possible workaround: you can retrieve the outputLimit from the service 
capabilities:

https://mast.stsci.edu/vo-tap/api/v0.1/hsc/capabilities

and adapt your query accordingly.


Thomas

Le 14/12/2023 à 14:37, Pierre Fernique a écrit :
>
>
> Dear TAP experts,
>
> While testing the various TAP services accessible via Aladin Desktop, 
> I discovered an interpretation of the MAXREC parameter that I hadn't 
> anticipated, and I'm wondering about its validity.
>
> For example, if I query MAST TAP HSC, with a MAXREC of 2M, I don't get 
> the table I want, but an error as shown below.
>
> https://mast.stsci.edu/vo-tap/api/v0.1/hsc/sync?REQUEST=doQuery&LANG=ADQL&*MAXREC=20000000*&QUERY=SELECT+table_name+FROM+TAP_SCHEMA.tables
>
> <VOTABLE version="1.4" 
> xsi:schemaLocation="http://www.ivoa.net/xml/VOTable/v1.3 
> http://www.ivoa.net/xml/VOTable/v1.3">
>    <DESCRIPTION>MAST VO TAP Service</DESCRIPTION>
>    <RESOURCE type="results">
>       <INFO name="QUERY_STATUS" value="ERROR">
> *Error in query maxrec: ensure this value is less than or equal to 100000*
>      </INFO>
>    </RESOURCE>
> </VOTABLE>
>
> But I would have expected to receive the result correctly, possibly 
> truncated (OVERFLOW mention) at the internal limit of the service 
> (100000).
>
> In fact, such an approach makes it difficult for the client to use 
> MAXREC, except by trial and error appoach. Either it's too high and I 
> get an error, or it's too low (but by how much) and I may not get the 
> full result when I could have. And finally, if I don't specify a 
> MAXREC, the server will apply the default value, even though I could 
> have asked for more.
>
> Any advice on how to deal with this problem?
>
> Thanks
> Pierre Fernique
>
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