Robert Haas wrote:
On Wed, Dec 9, 2009 at 2:37 PM, Andrew Dunstan <and...@dunslane.net> wrote:
I have just noticed while checking the EXPLAIN YAML patch that the non-text
explain formats are output as a single line with embedded line feeds, while
the text format is delivered as a set of text records, one per line. The
practical effect of this is that psql decorates the non-text format output
with continuation characters:
[snip]
Those + chars at the end of the line are ugly, to say the least, and they
make the supposedly machine-readable formats not so machine readable if
anyone wanted to c&p the output into a parser. (I'm mildly surprised this
hasn't been noticed before).
Maybe we need to teach psql not to do this formatting for EXPLAIN output?
Oh, dear. I think that line continuation syntax was recently added -
subsequent to the machine-readable EXPLAIN patch. The reason why it's
coded to emit everything as a single row is because that will be most
convenient for programs that are sucking down this data
programatically. Otherwise, they'll have to concatenate all the lines
that are returned.
And in fact for XML format, it's even worse: the data is returned as
type xml, but that obviously won't fly if we return each line as a
separate tuple.
On first blush, I'm inclined to suggest that the addition of + signs
to mark continuation lines is a misfeature.
I certainly agree we don't want to break up the non-text formats.
A simple if ugly hack would make psql use old-ascii print style (which
doesn't use these contionuation chars) if the first attribute in the
resultset was named 'QUERY PLAN'
If someone has a better suggestion I'm all ears.
cheers
andrew
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