HASH: Out of overflow pages. Out of luck.

Does anyone have experience hacking the HASH index code to allow more
overflow pages?

I get the following when indexing a table with about 300M entries:

db=# \d table1
Table "table1"
Attribute | Type | Modifier
-----------+--------------+----------
field1 | varchar(256) |
field2 | integer |
field3 | float8 |

db=# create index table1_field1 on table1 using hash(field1);
ERROR: HASH: Out of overflow pages. Out of luck.

This also happens for field2.

I looked in the source for postgresql-7.0.3 from
src/include/access/hash.h:

* The reason that the size is restricted to NCACHED (32) is because
* the bitmaps are 16 bits: upper 5 represent the splitpoint, lower 11
* indicate the page number within the splitpoint. Since there are
* only 5 bits to store the splitpoint, there can only be 32 splitpoints.
* Both spares[] and bitmaps[] use splitpoints as there indices, so there
* can only be 32 of them.
*/
#define NCACHED 32

Is there a way around this?! If not: what a horrific limitation.

Thanks! John