Remember that we were talking about supporting views, not tables.  And
if a view uses a slow query then you are in immediate danger of having a
slow COPY.  This may not be a problem but it needs to be discussed and
an agreement must be reached before introducing such a change (and not
during feature freeze).

this will definitely be the case - however, this is not what it was made for. it has not been made to be fast but it has been made to fulfill some other task. the reason why this has been implemented is: consider a large scale database containing hundreds of gigs of data. in our special case we have to export in a flexible way. the data which has to be exported comes from multiple tables (between 3 and 7 depending on the data we are looking at in this project. the export has to be performed in a flexible way and it needs certain parameters. defining tmp tables and store the data in there is simply not "nice" at all. in most cases exports want to transform data on the fly - speed is not as important as flexibility here.

so in my view the speed argument does not matter. if somebody passes a stupid query to copy he will get stupid runtimes - just like on ordinary sql. however, we can use COPY's capabilities to format / escape data to make exports more flexible. so basically it is a win.

   best regards,


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