Questions tagged [top-n]
322 questions
3
votes
2 answers
Top n records per group sql in access
I am making some software that tracks the scores of a test. There are multiple users, the details of which are stored in a user table. There is then a progress table which tracks a score with the date and the user who's score it is.
I can already…
Huddlespith
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3
votes
3 answers
Second highest value from Oracle DB's table
According to the tables:
USERS (user_name, email, balance)
How can I create a query that return the second highest user balance in the most efficient way ?
I successes to get this record (but not by the efficient way) with the query:
SELECT
*…
e o
- 31
- 2
3
votes
1 answer
Sorting a DStream and taking topN
I have some DStream in Spark Scala and I want to sort it then take the top N.
The problem is that whenever I try to run it I get NotSerializableException and the exception message says:
This is because the DStream object is being referred to from…
Ahmed El-Gamal
- 180
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3
votes
2 answers
Oracle 11g - top N order by is slow
I'm trying to retrieve the last 20 rows by time for users with more than 100K rows in a table with more than 1 million records. The query performance is fine (in ms) when the user has a small number of records. But takes more than 2 minutes to…
user2755442
- 83
- 3
3
votes
2 answers
Select or create a view of last 3 articles from more than 1 table
I have two tables. One has articles (article), what are static pages on website. Second has blog articles (blog_article), which articles are shown just in the blog page.
Now I want to show latest articles order by date on my homepage. It is easy to…
Patrik Krehák
- 2,595
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3
votes
1 answer
Hive - top n records within a group
I am currently using Hive and I have a table with the fields user_id and value. I want to order the values in descending order within each user_id and then only emit the top 100 records for each user_id. This is the code I am attempting to use:
DROP…
Maeve90
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3
votes
2 answers
Spark: Efficient way to get top K frequent values per key in (key, value) RDD?
I've an RDD of (key, value) pairs. I need to fetch top k values according to their frequencies for each key.
I understand that the best way to do this would be using combineByKey.
Currently here is what my combineByKey combinators look like
object…
sushant-hiray
- 1,838
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3
votes
3 answers
How to produce rank in Oracle
Need to rank the below by salary, with highest salary having rank 1.
The RANK column shown is what I'm after:
Empname sal address RANK
----------------------------------------------
Ram 3411 45,east road …
anirban
- 51
- 1
- 2
3
votes
1 answer
Oracle linked server top N syntax
I have a linked Oracle 11g server in Microsoft SQL Server 2012.
I am trying to retrieve a large linked dataset from Oracle and so to limit it I want to just get the first 100 records.
In SQL Server it's simply
select top 100 from ....
In Oracle…
ErickTreetops
- 3,189
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- 37
3
votes
1 answer
Top 10% of sum() Postgres
I'm looking to pull the top 10% of a summed value on a Postgres sever.
So i'm summing a value with sum(transaction.value) and i'd like the top 10% of the value
Quinn Olive
- 57
- 6
3
votes
5 answers
top 1 case in select statement on TSQL
I am having problem on this query. How can I fix this:
select (select case top 1 STATUS
when 'Inprocess' then 'Processing'
when 'Inworkbin' then 'Waiting In Draft'
end
from ICS_EMAIL_CONNECTIONS_TRX A
where…
cihadakt
- 3,054
- 11
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- 59
3
votes
3 answers
NHibernate select top N with condition on children using fetch
I have simple User entity:
public class User
{
public virtual int Id { get; set; }
public virtual DateTime CreationDate { get; set; }
public virtual DateTime ModifiedDate { get; set; }
public virtual string Email { get; set; }
…
Michael Logutov
- 2,551
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- 32
2
votes
1 answer
MySQL query to choose top camera choices based on multiple column values
Okay so I am trying to get some ideas on how to go about determining the top choices of camera I have from the table setup below. This is not a real scenario I am just trying to figure out the best way or some way to go about doing this.
So the…
BobPotter
- 23
- 4
2
votes
5 answers
Selecting top n elements of a group in Oracle
I have an Oracle table which has a name,value,time columns.Basically the table is for logging purposes to store what are the changes made to a particular name,what was the previous value and what time the change was made.
I need to formulate a query…
Harish
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2
votes
2 answers
R dataframe - Top n values in row with column names
I want to sort rowwise values in specific columns, get top 'n' values, and get corresponding column names in new columns.
The output would look something like this:
SL SW PL PW Species high1 high2 high3 col1 col2 col3
dbl>…
jaykay
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