[2002-01-13 16:42] Brent Verner said:
| [2002-01-13 15:17] Tom Lane said:
| | Brent Verner <brent@rcfile.org> writes:
| | > I fixed this by making an int* mapping from specified collist
| | > position to actual rd_att->attrs position.
| |
| | Sounds better.
| |
| | > I'm still a bit^W^W lost as hell on how the column default magic
| | > happens.
| |
| | I'd say use build_column_default() in src/backend/optimizer/prep/preptlist.c
| | to set up a default expression (possibly just NULL) for every column
| | that's not supplied by the input. That routine's not exported now, but
| | it could be, or perhaps it should be moved somewhere else. (Suggestions
| | anyone? Someplace in src/backend/catalog might be a more appropriate
| | place for it.)
|
| gotcha.
|
| | Then in the per-tuple loop you use ExecEvalExpr, or more likely
| | ExecEvalExprSwitchContext, to execute the default expressions.
| | The econtext wanted by ExecEvalExpr can be had from the estate
| | that CopyFrom already creates; use GetPerTupleExprContext(estate).
|
| many, many thanks!
|
| | You'll need to verify that you have got the memory context business
| | right, ie, no memory leak across rows. I think the above sketch is
| | sufficient, but check it with a memory-eating default expression
| | evaluated for a few million input rows ...
|
| Yes, the above info should get me through.
round two...
1) I (kludgily) exported build_column_default() from its current
location.
2) defaults expressions are now tried if a column is not in the
COPY attlist specification.
There are still some kinks... (probably more than I've thought of)
1) a column in attlist that is not in the table will cause a segv
in the backend.
2) duplicate names in attlist are still not treated as an error.
I believe the memory context issues are handled correctly, but I've
not run the few million copy tests yet, and I probably won't be able
to until late(r) tomorrow. No strangeness running compiled with
--enable-cassert. Regression tests still pass.
Sanity checks much appreciated.
cheers.
brent
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