returning only part of a rule set

Dave Potts wrote

I have a psql function that make a general sql query, returns a set of
results
Q. Is there anyway that I can limit the size of the result sets ?

SELECT *
FROM somewhere
LIMIT 50; <---

David J.

btw: what is a "psql function"?

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On 11/25/2014 01:27 PM, Dave Potts wrote:

I have a psql function that make a general sql query, returns a set of
results

Q. Is there anyway that I can limit the size of the result sets ?

Put a LIMIT on the query.

If that is not what you want then we will need to see the code and/or
get a more detailed explanation of where you want the limiting to occur.

Dave.

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Adrian Klaver
adrian.klaver@aklaver.com

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On 25/11/14 21:36, Adrian Klaver wrote:

On 11/25/2014 01:27 PM, Dave Potts wrote:

I have a psql function that make a general sql query, returns a set of
results

Q. Is there anyway that I can limit the size of the result sets ?

Put a LIMIT on the query.

If that is not what you want then we will need to see the code and/or
get a more detailed explanation of where you want the limiting to occur.

I tried that Limit applies to the total number of results from a
query, what I want to do is limit the total number of returns per
result set,

For example if my query returns a set of items such as id, foo,bar

Normally the result set is 3 set of records one with 3 entries, one with
2 entires and one with entry, the results would be.

1 xx,yy
2 xx,yy
3 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

If I am only interested in get 2 entries per result set, I would expect
to see

1 xx,yy
2 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

Using LIMIT only gives
1 xx,yy
2 xx,yy

Sorry for not explaining it very, I want to limit the size of an
inviduail set of records which is part of set of records.

Dave.

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On 11/25/2014 01:56 PM, Dave Potts wrote:

On 25/11/14 21:36, Adrian Klaver wrote:

On 11/25/2014 01:27 PM, Dave Potts wrote:

I have a psql function that make a general sql query, returns a set of
results

Q. Is there anyway that I can limit the size of the result sets ?

Put a LIMIT on the query.

If that is not what you want then we will need to see the code and/or
get a more detailed explanation of where you want the limiting to occur.

I tried that Limit applies to the total number of results from a
query, what I want to do is limit the total number of returns per
result set,

For example if my query returns a set of items such as id, foo,bar

Normally the result set is 3 set of records one with 3 entries, one with
2 entires and one with entry, the results would be.

1 xx,yy
2 xx,yy
3 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

So you are selecting on foo and bar?

If I am only interested in get 2 entries per result set, I would expect
to see

Actually <=2.
How do you determine which rows to keep, by id or something else?

1 xx,yy
2 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

Using LIMIT only gives
1 xx,yy
2 xx,yy

Sorry for not explaining it very, I want to limit the size of an
inviduail set of records which is part of set of records.

It would help if we could see the actual query you are using to get the
result sets, suitably anonymized if needed.

Dave.

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Adrian Klaver
adrian.klaver@aklaver.com

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Adrian Klaver-4 wrote

If I am only interested in get 2 entries per result set, I would expect
to see

Actually <=2.
How do you determine which rows to keep, by id or something else?

1 xx,yy
2 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

Using LIMIT only gives
1 xx,yy
2 xx,yy

Sorry for not explaining it very, I want to limit the size of an
inviduail set of records which is part of set of records.

It would help if we could see the actual query you are using to get the
result sets, suitably anonymized if needed.

The general answer is that you use a window clause and a row_number()
function over an appropriate partiton. Put that in a subquery then in the
outer query add a where clause for row_number <= 2.

David J.

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On 25/11/14 22:24, David G Johnston wrote:

Thanks List, I think this is the right way to go.

Adrian Klaver-4 wrote

If I am only interested in get 2 entries per result set, I would expect
to see

Actually <=2.
How do you determine which rows to keep, by id or something else?

1 xx,yy
2 xx,yy

1,dd,zz
2,dd,zz

1, ee,ff

Using LIMIT only gives
1 xx,yy
2 xx,yy

Sorry for not explaining it very, I want to limit the size of an
inviduail set of records which is part of set of records.

It would help if we could see the actual query you are using to get the
result sets, suitably anonymized if needed.

The general answer is that you use a window clause and a row_number()
function over an appropriate partiton. Put that in a subquery then in the
outer query add a where clause for row_number <= 2.

David J.

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