• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 215
  • Last Modified:

How to check sequence missing in postgress

Hi,

I have a table in PostgreSQL that the datatype of the field is (character varying(255) for some reason now I need to check this across all records if there is any sequence is missing, if any sequence is missing what are those sequences..

sample data

12345
12346
12347
12348
12350
12351
12356

Open in new window


 and what I want is
12349
12352
12353
12354
12355

Open in new window


and PostgreSQL version is 9.3 regards
0
hi4ppl
Asked:
hi4ppl
1 Solution
 
John_VidmarCommented:
This solution determines which key (myfield) has missing sequential value(s) after it, and how many are missing after that key:
create table mytable
( myfield int
 );

insert into mytable values (12345);
insert into mytable values (12346);
insert into mytable values (12347);
insert into mytable values (12348);
insert into mytable values (12350);
insert into mytable values (12351);
insert into mytable values (12356);

WITH sortedData as
(	SELECT	row_number() OVER (ORDER BY myfield) as rn
	,	myfield
	FROM	mytable
)
SELECT	a.myfield
,	b.myfield - a.myfield - 1 as missing_keys
FROM	sortedData a
JOIN	sortedData b	ON	a.rn = b.rn - 1
WHERE	b.myfield - a.myfield > 1

MYFIELD	MISSING_KEYS
------- ------------
12348	1
12351	4

Open in new window

0
 
hi4pplAuthor Commented:
Hi,

thanks, but my data field is character and this didn't work for that, can you suggest how to convert that and put it in this query?

regards
0
 
awking00Commented:
Determine the lowest and highest numeric values of your field -
select min(num) as start, max(num) as stop from
(select to_number(yourfield,'99999') as num  ==> using format mask to accommodate highest value
 from yourtable)

Then
select * from generate_series(start,stop)  ==> substituting values for start and stop from previous query
except
select to_number(yourfield,'99999') from yourtable
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
Tomas Helgi JohannssonCommented:
Hi!

Try this query

WITH seq_max AS (
SELECT max(yourvarcharfield) FROM yourtable
),
seq_min AS (
SELECT min(yourvarcharfield) FROM yourtable
)
SELECT * FROM generate_series((SELECT min FROM seq_min),(SELECT max FROM seq_max))
EXCEPT
SELECT yourvarcharfield FROM yourtable

Open in new window

Note that this query can be performance intensive on large tables.

Regards,
      Tomas Helgi
0
 
John_VidmarCommented:
Same solution as I posted previously, this time the key-field is varchar(255) instead of integer:
create table mytable
( myfield varchar(255)
 );

insert into mytable values ('12345');
insert into mytable values ('12346');
insert into mytable values ('12347');
insert into mytable values ('12348');
insert into mytable values ('12350');
insert into mytable values ('12351');
insert into mytable values ('12356');

WITH sortedData as
(	SELECT	row_number() OVER (ORDER BY myfield) as rn
	,	CAST(myfield as int) as myfield
	FROM	mytable
)
SELECT	a.myfield
,	b.myfield - a.myfield - 1 as missing_keys
FROM	sortedData a
JOIN	sortedData b	ON	a.rn = b.rn - 1
WHERE	b.myfield - a.myfield > 1

MYFIELD	MISSING_KEYS
------- ------------
12348	1
12351	4

Open in new window

0
 
awking00Commented:
The asker seems to want the missing values in the series, not the number of missing values. The following should return the missing values as character date:
with cte as
(select min(to_number(yourfield,'99999')) as start, max(to_number(yourfield,'99999')) as stop
 from yourtable)
select to_char(g.num,'99999')
from generate_series(cte.start,cte.stop) as g(num)
left join yourtable y on y.yourfield = to_char(g.num,'99999')
where y.yourfield is null;
0
 
awking00Commented:
typo - as character data (not date)
0
 
earth man2Commented:
select generate_series( col_name::integer + 1, alias_1::integer - 1 ) from
( select col_name,
lead(col_name) over( order by col_name) as alias_1
from tt ) as foo
where alias_1 <> (col_name::integer+1)::text;

 generate_series
-----------------
           12349
           12352
           12353
           12354
           12355
(5 rows)
0
 
awking00Commented:
and what I want is

12349
12352
12353
12354
12355
                                  1:
and what accepted solution provides is
MYFIELD      MISSING_KEYS
------- ------------
12348      1
12351      4

???
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Tackle projects and never again get stuck behind a technical roadblock.
Join Now