pgsql: In multi-insert, don't go into infinite loop on a huge tuple and

In multi-insert, don't go into infinite loop on a huge tuple and fillfactor.

If a tuple is larger than page size minus space reserved for fillfactor,
heap_multi_insert would never find a page that it fits in and repeatedly ask
for a new page from RelationGetBufferForTuple. If a tuple is too large to
fit on any page, taking fillfactor into account, RelationGetBufferForTuple
will always expand the relation. In a normal insert, heap_insert will accept
that and put the tuple on the new page. heap_multi_insert, however, does a
fillfactor check of its own, and doesn't accept the newly-extended page
RelationGetBufferForTuple returns, even though there is no other choice to
make the tuple fit.

Fix that by making the logic in heap_multi_insert more like the heap_insert
logic. The first tuple is always put on the page RelationGetBufferForTuple
gives us, and the fillfactor check is only applied to the subsequent tuples.

Report from David Gould, although I didn't use his patch.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/77a1ba20aa7b7caae4396e2afa5d86132fd36f6b

Modified Files
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src/backend/access/heap/heapam.c |    8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)