Count days between dates and find largest gap

Question

I need to find all members in our database from a calendar month that do not have a gap of 10+ days between sending data / or in the month total i.e. everyone in April 2018. The table is set up like so (although much larger):

+-----------+------------+
| member_id |  data_date |
+-----------+------------+
|         1 | 2018-04-10 |
|         5 | 2018-04-16 |
|         1 | 2018-04-11 |
|         2 | 2018-04-12 |
|         3 | 2018-04-13 |
|         4 | 2018-04-12 |
|         5 | 2018-04-15 |
|         3 | 2018-04-19 |
|         2 | 2018-04-17 |
|         1 | 2018-04-18 |
|         5 | 2018-04-10 |
|         2 | 2018-04-18 |
|         1 | 2018-04-08 |
|         2 | 2018-04-03 |
|         3 | 2018-04-02 |
|         4 | 2018-04-14 |
|         5 | 2018-04-15 |
|         3 | 2018-04-16 |
|         2 | 2018-04-19 |
|         1 | 2018-04-14 |
+-----------+------------+

(member_id,data_date) is defined UNIQUE. Each data_date represents one day that data was sent. There are duplicate data_dates for each member_id. I am running PostgreSQL 8.2.15. It is Greenplum.

There are up to 30 data_dates for each member_id in the month, I am having trouble figuring out how to find the largest gap without data being sent in the entire month for each member.

Here is an example of some test data:

create temp table tempdata  (
  member_id integer NOT NULL,
  data_date date
);

INSERT INTO tempdata(member_id, data_date) VALUES
   (1, '2017-04-01')
 , (1, '2017-04-02')
 , (1, '2017-04-03')
 , (1, '2017-04-04')
 , (1, '2017-04-05')
 , (1, '2017-04-06')
 , (1, '2017-04-07')
 , (1, '2017-04-08')
 , (1, '2017-04-09')
 , (1, '2017-04-10')
 , (1, '2017-04-11')
 , (1, '2017-04-12')
 , (1, '2017-04-13')
 , (1, '2017-04-14')
 , (1, '2017-04-15')
 , (1, '2017-04-16')
 , (1, '2017-04-17')
 , (1, '2017-04-18')
 , (1, '2017-04-19')
 , (1, '2017-04-20')
 , (1, '2017-04-21')
 , (1, '2017-04-22')
 , (1, '2017-04-23')
 , (1, '2017-04-24')
 , (1, '2017-04-25')
 , (1, '2017-04-26')
 , (1, '2017-04-27')
 , (1, '2017-04-28')
 , (1, '2017-04-29')
 , (1, '2017-04-30')
 , (2, '2017-04-09')
 , (2, '2017-04-10')
 , (2, '2017-04-11')
 , (2, '2017-04-12')
 , (3, '2017-04-01')
 , (3, '2017-04-02')
 , (3, '2017-04-03')
 , (3, '2017-04-04')
 , (3, '2017-04-05')
 , (3, '2017-04-06')
 , (3, '2017-04-07')
 , (3, '2017-04-08')
 , (3, '2017-04-09')
 , (3, '2017-04-10')
 , (3, '2017-04-11')
 , (3, '2017-04-12')
 , (3, '2017-04-13')
 , (3, '2017-04-14')
 , (3, '2017-04-15')
 , (3, '2017-04-16')
 , (3, '2017-04-17')
 , (3, '2017-04-18')
 , (3, '2017-04-19')
 , (3, '2017-04-20')
 , (3, '2017-04-21')
 , (3, '2017-04-22')
 , (3, '2017-04-23')
 , (3, '2017-04-24')
 , (3, '2017-04-25')
 , (3, '2017-04-26')
 , (3, '2017-04-27')
 , (3, '2017-04-28')
 , (3, '2017-04-29')
 , (3, '2017-04-30')
 , (4, '2017-04-01')
 , (4, '2017-04-02')
 , (4, '2017-04-03')
 , (4, '2017-04-04')
 , (4, '2017-04-05')
 , (4, '2017-04-06')
 , (4, '2017-04-07')
 , (4, '2017-04-08')
 , (4, '2017-04-09')
 , (4, '2017-04-10')
 , (4, '2017-04-11')
 , (4, '2017-04-12')
 , (4, '2017-04-13')
 , (4, '2017-04-14')
 , (4, '2017-04-15')
 , (4, '2017-04-16')
 , (4, '2017-04-17')
 , (4, '2017-04-18')
 , (4, '2017-04-19')
 , (4, '2017-04-20')
 , (4, '2017-04-21')
 , (4, '2017-04-22')
 , (5, '2017-04-01')
 , (5, '2017-04-02')
 , (5, '2017-04-03')
 , (5, '2017-04-04')
 , (5, '2017-04-05')
 , (5, '2017-04-06')
 , (5, '2017-04-07')
 , (5, '2017-04-08')
 , (5, '2017-04-09')
 , (5, '2017-04-10')
 , (5, '2017-04-11')
 , (5, '2017-04-12')
 , (5, '2017-04-13')
 , (5, '2017-04-14')
 , (5, '2017-04-15')
 , (5, '2017-04-16')
 , (5, '2017-04-17')
 , (5, '2017-04-18')
 , (5, '2017-04-22')
 , (5, '2017-04-23')
 , (5, '2017-04-24')
 , (5, '2017-04-25')
 , (5, '2017-04-26')
 , (5, '2017-04-27')
 , (5, '2017-04-29')
 , (5, '2017-04-30')
 , (6, '2017-04-01')
 , (6, '2017-04-02')
 , (6, '2017-04-03')
 , (6, '2017-04-04')
 , (6, '2017-04-05')
 , (6, '2017-04-06')
 , (6, '2017-04-07')
 , (6, '2017-04-08')
 , (6, '2017-04-09')
 , (6, '2017-04-10')
 , (7, '2017-04-01')
 , (7, '2017-04-04')
 , (7, '2017-04-05')
 , (7, '2017-04-06')
 , (7, '2017-04-07')
 , (7, '2017-04-08')
 , (7, '2017-04-09')
 , (7, '2017-04-11')
 , (7, '2017-04-12')
 , (7, '2017-04-13')
 , (7, '2017-04-14')
 , (7, '2017-04-15')
 , (7, '2017-04-16')
 , (7, '2017-04-17')
 , (7, '2017-04-18')
 , (7, '2017-04-19')
 , (7, '2017-04-21')
 , (7, '2017-04-22')
 , (7, '2017-04-26')
 , (7, '2017-04-27')
 , (7, '2017-04-28')
 , (7, '2017-04-30')
 , (8, '2017-04-02')
 , (8, '2017-04-03')
 , (8, '2017-04-04')
 , (8, '2017-04-05')
 ;    

Answer 1

Updating with the answer that I figured out for anyone interested:

drop table if exists tempdata;
create temp table tempdata as
select distinct member_id
from (
  select member_id
    , max(data_date) over (partition by member_id order by data_date) start_range
    , lead(data_date) over (partition by member_id order by data_date) end_range
  from tempmembers
) as c
where c.end_range-c.start_range > interval'9 days'
    ;

I was able to use this and then remove the ids that i found from the initial table.