Thread

1. no error context for index updates?

   Peter Eisentraut <peter_e@gmx.net> — 2012-01-31T18:17:25Z

   Attached is a test case reduced from a real application.  There is a
   table with an index on a function written in PL/Python.  There is a
   second PL/Python function that executes an INSERT into the table,
   causing an index update.  If the function used by the index fails, we
   get an error message with context information, e.g.,
   
   ERROR:  spiexceptions.InternalError: plpy.Error: boom
   CONTEXT:  Traceback (most recent call last):
     PL/Python function "test2", line 3, in <module>
       rv = plpy.execute(plan, [a, b])
   PL/Python function "test2"
   
   I had been debugging the heck out of this function trying to figure out
   where that particular exception is coming from, but it wasn't happening
   on that function at all.
   
   What I'd like to see if additional context like this:
   
   CONTEXT: index updates of table "test"
   CONTEXT: ....
   PL/Python function "test1"
   
   The second test case I'm attaching shows that the same thing happens
   with PL/Perl, so it's not a problem of a particular PL.
   
   Any ideas whether we could make this happen?
   
   

2. Re: no error context for index updates?

   Tom Lane <tgl@sss.pgh.pa.us> — 2012-01-31T22:23:04Z

   Peter Eisentraut <peter_e@gmx.net> writes:
   > Any ideas whether we could make this happen?
   
   Presumably you could do it by setting up an error context stack entry
   within FormIndexDatum.  I'd want to be convinced that there was no
   performance hit, but if you were to do it only in the expression-column
   code path that would probably put it into the noise.  (So you could
   actually mention the particular index column name, too, if you had a
   mind to do that.)
   
   [ pokes around a bit... ]  The major issue appears to be that
   FormIndexDatum doesn't actually receive anything that tells it the index
   name.  I'm not sure why we don't have a Relation pointer for the index
   in there, but it looks like most of the work would be to verify that
   that's safe --- are there any code paths where the index rel wouldn't
   stay open for the lifetime of the IndexInfo node?  Or maybe, since
   IndexInfo *is* a node and Relation isn't, it'd be better to just make
   callers pass the index Relation separately.
   
   			regards, tom lane