Re: [HACKERS] Hash support for grouping sets

The following review has been posted through the commitfest application:
make installcheck-world:  tested, failed
Implements feature:       not tested
Spec compliant:           not tested
Documentation:            not tested

On linux/gcc the patch generates a warning in nodeAgg.c that is fairly easy
to fix.  Using -Werror to make catching the error easier, I get:

make[3]: Entering directory `/home/mark/postgresql.clean/src/backend/executor'
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute
-Wformat-security-fno-strict-aliasing -fwrapv -O2 -Werror -I../../../src/include -D_GNU_SOURCE   -c -o nodeAgg.o
nodeAgg.c-MMD -MP -MF .deps/nodeAgg.Po
 
cc1: warnings being treated as errors
nodeAgg.c: In function ‘ExecAgg’:
nodeAgg.c:2053: error: ‘result’ may be used uninitialized in this function
make[3]: *** [nodeAgg.o] Error 1
make[3]: Leaving directory `/home/mark/postgresql.clean/src/backend/executor'
make[2]: *** [executor-recursive] Error 2
make[2]: Leaving directory `/home/mark/postgresql.clean/src/backend'
make[1]: *** [all-backend-recurse] Error 2
make[1]: Leaving directory `/home/mark/postgresql.clean/src'
make: *** [all-src-recurse] Error 2


There are two obvious choices to silence the warning:

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f059560..8959f5b 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -2066,6 +2066,7 @@ ExecAgg(AggState *node)                               break;                       case
AGG_PLAIN:                      case AGG_SORTED:
 
+                       default:                               result = agg_retrieve_direct(node);
        break;               }
 

which I like better, because I don't expect it would create
an extra instruction in the compiled code, but also:

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index f059560..eab2605 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -2050,7 +2050,7 @@ lookup_hash_entries(AggState *aggstate)TupleTableSlot *ExecAgg(AggState *node){
-       TupleTableSlot *result;
+       TupleTableSlot *result = NULL;       if (!node->agg_done)       {