3
votes
1answer
83 views

Simple SELECT takes forever, but works as a subquery. Why?

I'm running a MySQL 5.1 server and I have a MyISAM table called my_table with nearly 5 million records. Its structure is the following: ...
0
votes
1answer
96 views

SQL Server Index Scan Actual Executions

I have a fairly complicated query and running it on two databases with same schemas, but with different data produces different result. On database D1 the elapsed time is around 1 second, and the ...
6
votes
2answers
2k views

How to optimise T-SQL query using Execution Plan

I have a SQL query that I have spent the past two days trying to optimise using trial-and-error and the execution plan, but to no avail. Please forgive me for doing this but I will post the entire ...
1
vote
2answers
370 views

Updating a table efficiently using JOIN

I have a table that has the details of households and another that has the details of all the persons associated with the households. For the household table I have a primary key defined using two ...
3
votes
1answer
108 views

can sql generate a good plan for this procedure?

I have read that procs that do not always do the same thing per se, will not always have a good plan generated. That is (correct me if I'm wrong), if I have a proc that if the day is even it reads ...
2
votes
2answers
771 views

In DB2, how can I disable NLJOIN?

I want to indicate to the optimizer, via SET or optimization profiles, that NLJOIN shouldn't be used at all when optimizing a query. I've been looking for this for a while without any success. I ...