pointed out, it would need a 2nd pass after the whole query is processed to
correctly check that an unknown Param is coerced to the same target type
everywhere. Adding the 2nd pass would add a lot more code, which doesn't
seem worth the risk given that there isn't much of a use case for passing
unknown Params in the first place. The code would work without that check,
but it might be confusing and the behavior would be different from the
varparams case.
Instead, just coerce all unknown params in a PL/pgSQL USING clause to text.
That's simple, and is usually what users expect.
Revert the patch in CVS HEAD and master, and backpatch the new solution to
8.4. Unlike the previous solution, this applies easily to 8.4 too.
parse_analyze() function. That case occurs e.g with PL/pgSQL
EXECUTE ... USING 'stringconstant'.
The coercion with a CoerceViaIO node. The result is similar to the coercion
via input function performed for unknown constants in coerce_type(),
except that this happens at runtime.
Backpatch to 9.0. The issue is present in 8.4 as well, but the coerce param
hook infrastructure this patch relies on was introduced in 9.0. Given the
lack of user reports and harmlessness of the bug, it's not worth attempting
a different fix just for 8.4.
in the parameter array. Noted while experimenting with an example
from Pavel. This wouldn't come up in normal use, but it ought to honor
the specification that a parameter array can have unused slots.
recent proposal. As proof of concept, remove knowledge of Params from the
core parser, arranging for them to be handled entirely by parser hook
functions. It turns out we need an additional hook for that --- I had
forgotten about the code that handles inferring a parameter's type from
context.
This is a preliminary step towards letting plpgsql handle its variables
through parser hooks. Additional work remains to be done to expose the
facility through SPI, but I think this is all the changes needed in the core
parser.
Heikki Linnakangas
Bruce Momjian
Tom Lane