rdbms

I really do not understand the actual reason behind hadoop scaling better than RDBMS . Can anyone please explain at a granular level ? Has this got something to do with underlying datastructures & algorithms Ravindra babu RDBMS have challenges in handling huge data volumes of Terabytes & Peta bytes. Even if you have Redundant Array of Independent/Inexpensive Disks (RAID) & data shredding, it does not scale well for huge volume of data. You require very expensive hardware. EDIT: To answer, why RDBMS cannot scale, have a look at Overheads of RBDMS . Logging . Assembling log records and tracking

Recently, I started changing some of our applications to support MS SQL Server as an alternative back end. One of the compatibility issues I ran into is the use of MySQL's CREATE TEMPORARY TABLE to create in-memory tables that hold data for very fast access during a session with no need for permanent storage. What is the equivalent in MS SQL? A requirement is that I need to be able to use the temporary table just like any other, especially JOIN it with the permanent ones. @Keith This is a common misconception: Table variables are NOT necessarily stored in memory. In fact SQL Server decides

What's the correct or most popular name for an "association table"? I've heard lookup, associative, resolving, mapping and junction table. Raj Kaimal Cross reference table. CustomerProductXRef. There is no "correct" name, but the academic name would be an "Associative Table" (see See the Wikipedia article Associative Entity ). Other common names are (in alphabetical order): Association table Bridge table Cross-reference table Crosswalk Intermediary table Intersection table Join table Junction table Link table Linking table Many-to-many resolver Map table Mapping table Pairing table

Let's assume the following: Table A id | value ---------- 1 | red 2 | orange 5 | yellow 10 | green 11 | blue 12 | indigo 20 | violet I have a list of id's (10, 11, 12, 13, 14) that can be used to look up id's in this table. This list of id's is generated in my frontend. Using purely SQL, I need to select the id's from this list (10, 11, 12, 13, 14) that do not have entries in Table A (joining on the 'id' column). The result should be the resultset of id's 13 and 14. How can I accomplish this using only SQL? (Also, I'd like to avoid using a stored procedure if possible) The only approach I can

When would a database design be described as overnormalized? Is this characterization an absolute one? Or is it dependent on the way it is used in the application? Thanks. In the general sense, I think that overnormalized is when you are doing so many JOINs to retrieve data that it is causing notable performance penalties and deadlocks on your database, even after you've tuned the heck out of your indexes. Obviously, for huge applications and sites like MySpace or eBay, de-normalization is a scaling requirement. As a developer for several small businesses, I tell you that in my experience it's

I know that this sort of goes against the principles of a relational database but let me describe the situation. I have a page where the user will place a number of items. ________________ | -Item1 | | -Item2 | | -Item3 | | -Item4 | |________________| These items have must stay in a the order the user gives them. However this order may be changed an arbitrary number of times by the user. ________________ | -Item1 | | -Item4 | | -Item2 | | -Item3 | |________________| Approach 1 My original thought was to give the items an index to represent thier place in the list Page Item ----------- --------