Temp file missing during large pgbench data set

Hi,

I'm using latest git master (latest entry
0816fad6eebddb8f1f0e21635e46625815d690b9) and I'm getting an error
when trying to create a large data set with pgbench:

thom(at)swift:~/Development$ createdb pgbench
thom(at)swift:~/Development$ pgbench -i -s 100 pgbench
NOTICE: table "pgbench_branches" does not exist, skipping
NOTICE: table "pgbench_tellers" does not exist, skipping
NOTICE: table "pgbench_accounts" does not exist, skipping
NOTICE: table "pgbench_history" does not exist, skipping
creating tables...
10000 tuples done.
20000 tuples done.
30000 tuples done.
40000 tuples done.

<snip>

9970000 tuples done.
9980000 tuples done.
9990000 tuples done.
10000000 tuples done.
set primary key...
NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index
"pgbench_branches_pkey" for table "pgbench_branches"
NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index
"pgbench_tellers_pkey" for table "pgbench_tellers"
NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index
"pgbench_accounts_pkey" for table "pgbench_accounts"
LOG: could not stat file "base/pgsql_tmp/pgsql_tmp8056.0": Success
STATEMENT: alter table pgbench_accounts add primary key (aid)
vacuum...done.

I've tried this multiple times and the result is the same. I'm not
sure what this message means, but the primary key is created
successfully. If I reduce the scale to 20 the error doesn't occur.

The following changes were made to my postgresql.conf file:

max_connections = 300
shared_buffers = 3900MB
temp_buffers = 16MB
work_mem = 16MB
maintenance_work_mem = 256MB
checkpoint_segments = 32
random_page_cost = 1.1
effective_cache_size = 12GB

All other values are at default.

Is this anything to worry about?

--
Thom