2017-01-24 21:38 GMT+01:00 Alvaro Herrera <alvhe...@2ndquadrant.com>:
> Pavel Stehule wrote: > > > * 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; > > Please fix. > > -- > Álvaro Herrera https://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services >