> * SELECT (xmltable(..)).* + regress tests > * compilation and regress tests without --with-libxml
Thanks. I just realized that this is doing more work than necessary -- I think it would be simpler to have tableexpr fill a tuplestore with the results, instead of just expecting function execution to apply ExecEvalExpr over and over to obtain the results. So evaluating a tableexpr returns just the tuplestore, which function evaluation can return as-is. That code doesn't use the value-per-call interface anyway.
I also realized that the expr context callback is not called if there's an error, which leaves us without shutting down libxml properly. I added PG_TRY around the fetchrow calls, but I'm not sure that's correct either, because there could be an error raised in other parts of the code, after we've already emitted a few rows (for example out of memory). I think the right way is to have PG_TRY around the execution of the whole thing rather than just row at a time; and the tuplestore mechanism helps us with that.
I think it would be good to have a more complex test case in regress -- let's say there is a table with some simple XML values, then we use XMLFOREST (or maybe one of the table_to_xml functions) to generate a large document, and then XMLTABLE uses that document as input document.
I have a 16K lines long real XML 6.MB. Probably we would not to append it to regress tests.
It is really fast - original customer implementation 20min, nested our xpath implementation 10 sec, PLPython xml reader 5 sec, xmltable 400ms
I have a plan to create tests based on pg_proc and CTE - if all works, then the query must be empty
with x as (select proname, proowner, procost, pronargs, array_to_string(proargnames,',') as proargnames, array_to_string(proargtypes,',') as proargtypes from pg_proc), y as (select xmlelement(name proc, xmlforest(proname, proowner, procost, pronargs, proargnames, proargtypes)) as proc from x), z as (select xmltable.* from y, lateral xmltable('/proc' passing proc columns proname name, proowner oid, procost float, pronargs int, proargnames text, proargtypes text)) select * from z except select * from x;