Question : Could anyone please point me to a benchmark comparing the time spent by the query optimiser relative to […]
Category: Database Optimization
Serial Plan in plan cache
Question : I have a query which was executing slowly earlier. Later I found out that it was not running […]
In DB2, what are the alternative ways of evaluating an index’s (or several indexes) benefit?
Question : I’m trying to evaluate different approaches to analyzing the benefit of changing the set of indexes that are […]
How to restructure this slow query containing subquery?
Question : This query takes about 2-6 seconds to run depending which tag id(s) is/are selected: SELECT t2.id, t2.name, count(*) […]
What exactly does PostgreSQL (or other databases) do internally when you “prepare” a query rather than just running it directly?
Question : When I face a huge number of repeated INSERTs in a loop, I tend to first create a […]
What is the impact on the Cost-Based Optimizer (CBO) when implementing ISCSI SAN solid-state drives
Question : A Microsoft Technet article recommends creating a secondary file group as the default file group (see reference below). […]
How do I speed up a string manipulation query where I want to replace characters, extract certain values and update a table with the results?
Question : I am trying to extract information from strings that are presented in a key-value format, with the keys […]
Slow performance on averaging query
Question : I am fairly new to DBMS and backend management, and was hoping to get some advice on the […]
Help to optimize specific SQL query
Question : I have WORKLOGTABLE which has index on RECORDKEY column. WORKLOG table has currently 1,200,000 records When I do […]
Join external data in SELECT query
Question : I have few (~20) names of products corresponding to an integer id that needs to be joined on […]