How to use windowing functions to find gaps in sequences grouped by a column, in PostgreSQL
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I have a table structure which has 2 columns: client_id, order_no, and both are integers. I'd like to find gaps in order_no in the data so that, for example, for a table containing these rows:
42, 1
43, 1
42, 2
43, 5
43, 6
42, 3
the output contains the client_id, and boundaries of the gaps, like this:
43, 2, 4
Note that there's no row with client_id=42 because there are no gaps in its data.
I've tried this for the core part of the query:
select
client_id,
order_no as start_order_no,
lead(order_no) over (order by client_id, order_no) as end_order_no
but that apparently doesn't do what I want, and I suspect it's because of client_id in the OVER part.
postgresql window-functions gaps-and-islands
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
bumped to the homepage by Community♦ 51 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
add a comment |
I have a table structure which has 2 columns: client_id, order_no, and both are integers. I'd like to find gaps in order_no in the data so that, for example, for a table containing these rows:
42, 1
43, 1
42, 2
43, 5
43, 6
42, 3
the output contains the client_id, and boundaries of the gaps, like this:
43, 2, 4
Note that there's no row with client_id=42 because there are no gaps in its data.
I've tried this for the core part of the query:
select
client_id,
order_no as start_order_no,
lead(order_no) over (order by client_id, order_no) as end_order_no
but that apparently doesn't do what I want, and I suspect it's because of client_id in the OVER part.
postgresql window-functions gaps-and-islands
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
bumped to the homepage by Community♦ 51 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
2
You probably meantpartition by client_id order by order_no
– mustaccio
Nov 1 '18 at 18:41
add a comment |
I have a table structure which has 2 columns: client_id, order_no, and both are integers. I'd like to find gaps in order_no in the data so that, for example, for a table containing these rows:
42, 1
43, 1
42, 2
43, 5
43, 6
42, 3
the output contains the client_id, and boundaries of the gaps, like this:
43, 2, 4
Note that there's no row with client_id=42 because there are no gaps in its data.
I've tried this for the core part of the query:
select
client_id,
order_no as start_order_no,
lead(order_no) over (order by client_id, order_no) as end_order_no
but that apparently doesn't do what I want, and I suspect it's because of client_id in the OVER part.
postgresql window-functions gaps-and-islands
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
I have a table structure which has 2 columns: client_id, order_no, and both are integers. I'd like to find gaps in order_no in the data so that, for example, for a table containing these rows:
42, 1
43, 1
42, 2
43, 5
43, 6
42, 3
the output contains the client_id, and boundaries of the gaps, like this:
43, 2, 4
Note that there's no row with client_id=42 because there are no gaps in its data.
I've tried this for the core part of the query:
select
client_id,
order_no as start_order_no,
lead(order_no) over (order by client_id, order_no) as end_order_no
but that apparently doesn't do what I want, and I suspect it's because of client_id in the OVER part.
postgresql window-functions gaps-and-islands
postgresql window-functions gaps-and-islands
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
edited Nov 1 '18 at 19:03
MDCCL
6,85331745
6,85331745
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
asked Nov 1 '18 at 18:30
Ivan VorasIvan Voras
27019
27019
bumped to the homepage by Community♦ 51 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
bumped to the homepage by Community♦ 51 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
2
You probably meantpartition by client_id order by order_no
– mustaccio
Nov 1 '18 at 18:41
add a comment |
2
You probably meantpartition by client_id order by order_no
– mustaccio
Nov 1 '18 at 18:41
2
2
You probably meant
partition by client_id order by order_no– mustaccio
Nov 1 '18 at 18:41
You probably meant
partition by client_id order by order_no– mustaccio
Nov 1 '18 at 18:41
add a comment |
1 Answer
1
active
oldest
votes
You should use a CTE or a subquery to get the lead order_no first.
select client_id,
order_no + 1 as c1,
no - 1 c2
from (select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl) ct
where no is not null
and no - order_no > 1;
with ct as
(
select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl
)
select client_id,
order_no + 1 as c1,
no - 1 c2
from ct
where no is not null
and no - order_no > 1;
client_id | c1 | c2
--------: | -: | -:
43 | 2 | 4
db<>fiddle here
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
add a comment |
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You should use a CTE or a subquery to get the lead order_no first.
select client_id,
order_no + 1 as c1,
no - 1 c2
from (select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl) ct
where no is not null
and no - order_no > 1;
with ct as
(
select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl
)
select client_id,
order_no + 1 as c1,
no - 1 c2
from ct
where no is not null
and no - order_no > 1;
client_id | c1 | c2
--------: | -: | -:
43 | 2 | 4
db<>fiddle here
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
add a comment |
You should use a CTE or a subquery to get the lead order_no first.
select client_id,
order_no + 1 as c1,
no - 1 c2
from (select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl) ct
where no is not null
and no - order_no > 1;
with ct as
(
select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl
)
select client_id,
order_no + 1 as c1,
no - 1 c2
from ct
where no is not null
and no - order_no > 1;
client_id | c1 | c2
--------: | -: | -:
43 | 2 | 4
db<>fiddle here
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
add a comment |
You should use a CTE or a subquery to get the lead order_no first.
select client_id,
order_no + 1 as c1,
no - 1 c2
from (select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl) ct
where no is not null
and no - order_no > 1;
with ct as
(
select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl
)
select client_id,
order_no + 1 as c1,
no - 1 c2
from ct
where no is not null
and no - order_no > 1;
client_id | c1 | c2
--------: | -: | -:
43 | 2 | 4
db<>fiddle here
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
You should use a CTE or a subquery to get the lead order_no first.
select client_id,
order_no + 1 as c1,
no - 1 c2
from (select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl) ct
where no is not null
and no - order_no > 1;
with ct as
(
select client_id,
order_no,
lead(order_no)
over (partition by client_id order by client_id, order_no) as no
from tbl
)
select client_id,
order_no + 1 as c1,
no - 1 c2
from ct
where no is not null
and no - order_no > 1;
client_id | c1 | c2
--------: | -: | -:
43 | 2 | 4
db<>fiddle here
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
answered Nov 1 '18 at 21:55
McNetsMcNets
16.4k42261
16.4k42261
add a comment |
add a comment |
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2
You probably meant
partition by client_id order by order_no– mustaccio
Nov 1 '18 at 18:41