select avg("datediff") as "average time between blocks in seconds" from(
select block_timestamp as "block_time",
lag(block_timestamp) over (order by block_timestamp asc) as "block_time-1",
datediff(second, "block_time-1", "block_time") as "datediff"
from arbitrum.core.fact_blocks)
where "datediff" < 60