Tagged Questions

0
votes
2answers
95 views

Estimated Execution Plan SQL Server Sort?

I'm running a query and its taking a age to execute, looking at the execution plan I can see that 51% of the cost is in the SORT? when in the actual query i am not ORDERING BY anything. Anyone got ...
3
votes
2answers
71 views

Algorithmic order of table indexes for table operations

I have not been able to find a clear indication of the impact table indexes have on the algorithmic order of table operations. I am not interested in the nuts & bolts of specific implementations; ...
2
votes
1answer
71 views

sorting groups of related rows by average values while keeping the groups together

I'm using PostgreSQL 8.4, but would like a standard SQL solution if possible. Consider the following table. corrmodel=# SELECT * from data limit 1; id | datasubgroup_id | datafile_id | ...
1
vote
1answer
112 views

Index strategy for a Queue Table, getting rid of filesort

I am trying to get rid of a filesort operation (and preferably also optimize a bottleneck query). We are using an innodb mysql table as a queue to process various incoming business activities. It is ...
7
votes
5answers
1k views

Oracle sort varchar2 column with special characters last

How can I sort in Oracle a Varchar2 or NVarchar2 column to be in my own custom defined order. Or are any existing options available that will put letters first, then numbers, then all special ...
4
votes
3answers
765 views

Why are NULLs sorted first?

Why is it that when we have a NULL value in a column and we order by the value ascending, the NULLs are sorted first? select 1 as test union all select 2 union all select NULL union all select 3 ...