I found another bug in btree index.  Looking at the code it seems that NULL
keys are never used to build or scan a btree index (see the explain commands
in the example).  However this is not the case when a null key is retrieved
in an outer loop of a join select and used in an index scan of an inner loop.
This bug causes at least three kinds of problems:

1)  the backend crashes when it tries to compare a text string with a null.

2)  it is not possible to find tuples with null keys in a join.

3)  null is considered equal to 0 when the datum is passed by value, see
    the last query.

Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>

It's bug in nodeAgg.c on lines 241, 242:

                null_array = malloc(nagg);
                for (i=0;i<nagg;i++)
                    null_array[i] = 'n';
                oneTuple = heap_formtuple(tupType, tupValue, null_array);

- your query has not only aggregates but also 'group by-ed' fields and so
null_array should contain tupType->natts elements (tupType->natts > nagg in
your case).

Patch follows and it's very simple.

VAdim

Submitted by:  Massimo Dal Zotto <dz@cs.unitn.it>

execute an sql function containing an utility command (create, notify, ...).
The bug is part in the planner, which returns a number of plans different
than the number of commands if there are utility commands in the query, and
in part in the function executor which assumes that all commands are normal
query commands and causes a SIGSEGV trying to execute commands without plan.

Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>

|
|Here's a patch for Version 2 only.  It just adds an Assert to catch some
|inconsistencies in the catalog classes.
|
|--
|Bryan Henderson                                    Phone 408-227-6803
|San Jose, California
|

The problem is that the function arguments are not considered as possible key
candidates for index scan and so only a sequential scan is possible inside
the body of a function.  I have therefore made some patches to the optimizer
so that indices are now used also by functions.  I have also moved the plan
debug message from pg_eval to pg_plan so that it is printed also for plans
genereated for function execution.  I had also to add an index rescan to the
executor because it ignored the parameters set in the execution state, they
were flagged as runtime variables in ExecInitIndexScan but then never used
by the executor so that the scan were always done with any key=1. Very odd.
This means that an index rescan is now done twice for each function execution
which uses an index, the first time when the index scan is initialized and
the second when the actual function arguments are finally available for the
execution.  I don't know what is the cost of an double index scan but I
suppose it is anyway less than the cost of a full sequential scan, at leat
for large tables. This is my patch, you must also add -DINDEXSCAN_PATCH in
Makefile.global to enable the changes.

Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>

	- code compile tested, but due to a yet unresolved problem with
          parse.h's creation, compile not completed...

|
|This patch fixes a backend crash that happens sometimes when you try to
|join on a field that contains NULL in some rows.  Postgres tries to
|compute a hash value of the field you're joining on, but when the field
|is NULL, the pointer it thinks is pointing to the data is really just
|pointing to random memory.  This forces the hash value of NULL to be 0.
|
|It seems that nothing matches NULL on joins, even other NULL's (with or
|without this patch).  Is that what's supposed to happen?
|

        - src/backend/catalog/*
                - no changes
        - src/backend/executor/*
                - change how nodeHash.c handles running out of memory
        - src/backend/optimizer/*
                - mostly cosmetic changes

'select distinct on' causes backend to crash

submitted by: Chris Dunlop    chris@onthe.net.au