3
votes
1answer
180 views

Processing every leaf under a node in a tree efficiently

Short version: In a tree (non-binary) with many levels of children, where each node can have multiple leaves, what is the best way to tally leaves that meet a certain condition given a node? Long, ...
3
votes
2answers
2k views

Fast extraction to text file from oracle database [closed]

I have to extract around 3 million records from two different databases for further processing. Currently, I execute the queries via SQL*Plus and spool the results to a plain text file. This queries ...
3
votes
1answer
1k views

Rails application - how to optimize/reduce database calls when iterating over a collection

What's the best way to optimize a Rails app where you need to pull info from the database for a collection of items? For example, if I am building an online forum system... I would have a number of ...
8
votes
6answers
6k views

Is there any reason to use varchar over text columns in a database?

Is varchar just a remnant from before text came around, or are there use cases where you would want to use a varchar? (Or char for that matter..) (I use Postgres and MySQL (MyISAM) daily, so those ...
1
vote
2answers
317 views

Is it more efficient to query once for all settings, or query whenever a setting is needed?

For my blog script I have a usergroup and permission system set up. Each user is assigned to a usergroup and I have a long list of permission settings. Both are stored in a MySQL database. At the ...