palloc() too large on pg_buffercache with large shared_buffers - Mailing list pgsql-hackers

Hello,

It looks to me pg_buffercache tries to allocate more than 1GB using
palloc(), when shared_buffers is more than 256GB.

# show shared_buffers ;
 shared_buffers
----------------
 280GB
(1 row)

# SELECT buffers, d.datname, coalesce(c.relname, '???')
    FROM (SELECT count(*) buffers, reldatabase, relfilenode
            FROM pg_buffercache group by reldatabase, relfilenode) b
       LEFT JOIN pg_database d ON d.oid = b.reldatabase
       LEFT JOIN pg_class c ON d.oid = (SELECT oid FROM pg_database
                                         WHERE datname = current_database())
                           AND b.relfilenode = pg_relation_filenode(c.oid)
           ORDER BY buffers desc;
ERROR:  invalid memory alloc request size 1174405120

It is a situation to use MemoryContextAllocHuge(), instead of palloc().
Also, it may need a back patching?

Thanks,
--
NEC Business Creation Division / PG-Strom Project
KaiGai Kohei <kaigai@ak.jp.nec.com>