Review comments on createPartitions() in pgbench.c

Hello developer people,

I was reviewing the createPartitions() function in pgbench.c and noticed a
few potential robustness concerns that may be worth reviewing.

Observations:

-

possible overflow readability concern in the part_size calculation
-

reliance on Assert(partitions > 0) for runtime safety
-

PQExpBuffer reuse without explicit resetPQExpBuffer()
-

possible edge-case considerations for uneven RANGE partition boundaries

I have not yet reproduced a failure case, so these are currently review
observations rather than confirmed bugs.

Possible improvement for the calculation section:

int64 total = (int64) naccounts * scale;
int64 part_size = (total + partitions - 1) / partitions;

Thank you for your work on PostgreSQL.

Regards,
Vellaipandiyan