oracle sql to get min timestamp when the count of results large than a number -


in order improve performance, need sql implement following requirement.

if there table , has following column:

id timestamp value

how can min timestamp(e.g. :t1) when count of result > 100000 ?

then following sql result--count(*) > 100000

select count(*) table  timestamp < :t1

my understanding of question is: find earliest timestamp in table there @ least 100,000 earlier rows.

there many ways it; main difficulty trying come efficient one.

i think analytic-function approach work well. obvious choice use count:

select min(timestamp) (   select timestamp, count(*) on (order timestamp rows between unbounded preceding , 1 preceding) earlier_rows   table ) earlier_rows >= 100000

but suspect using rank or similar faster:

select min(timestamp) (   select timestamp, rank() on (order timestamp) time_rank   table ) time_rank > 100000

i'm not sure off top of head, these may give different results if there duplicate timestamps.


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