Oracle Select Into

Stumped for a new read?

Based on the recent thriller and detective books I've read, the Siouxland Library's online Book-O-Matic says I might like a series by Chelsea Cain that starts with "Heartsick."

It's about a Portland detective who spent 10 years tracking a beautiful serial killer, but in the end she's the one who catches him. Cool! I'll give it a try.

If you're looking for suggestions for your next book or series to dive into, try the library's new online service with a name that sounds like a '50s-style machine.

Book-O-Matic started last week on the library's Facebook page. Just search Facebook for "Siouxland Libraries."

Readers can post the last three books they've read, then librarians compare notes, do some research and brainstorming and post the next title a reader might enjoy, visible to other viewers of the page as well.

Included in the prompt answer is a link to the book's description.

"It's a blend of the traditional library services mixed with new social networking," says Heather Stephenson, a librarian who helps post responses from the Main Branch location.

"A group of us come up with the suggestions based on our knowledge - we all read different things," Stephenson says. "We consider the elements of the books they've read and then come up with a profile, guessing a little bit about their personality and preferences."

They got the idea from a story in a library journal that outlines how another library started something similar called The Book Oracle.

For Sioux Falls reading enthusiast Taté Walker, seeing what other people are reading, and the suggestions for their future consideration, is more fun than than what she got as her own recommendation.

"The Book-O-Matic told me to try 'Book of Lost Things' by John Connolly, but I've already read it," says Walker, 27. That was based on her recent reading of "Game of Thrones," "Nerd Do Well" and "To Kill a Mockingbird."

Since the last title was book-club mandated, she included her last personal read, the Sookie Stackhouse book "Dead Reckoning."

"If I see people there who have read books I like, maybe they list other books I would like that I haven't read," Walker says. "I'm pretty impressed with the titles Sioux Falls people are reading. I haven't seen things like Harlequin romance books listed there.

IOT Part 4 – Greatly Boosting Buffer Cache Efficiency « Martin ...

≪……IOT3 – Significantly reducing IO

So far I have covered the basics of Index Organized Tables, created some examples and shown how IOTs can help reduce the cost of single row selects and then how they can greatly aid range scans. Follow the above links for details.

Now I’d like to show that the use of IOTs has the potential to make your block buffer cache (BBC) far more efficient. Going to disc is very,very slow compared to going to memory {NB solid state storage improves this situation but does not remove it}. The block buffer cache has always been critical to oracle SQL Select performance as it allows you to access data in memory rather than disc and in general the more block buffer cache you have the faster your system will be. – because more data is hosted on the same number of spindles and those spindles are not themselves getting faster – I digress, for more details see posts Big Discs are Bad and IOPs and Form Factors }

In the scenario I’ve covered in my previous posts on IOTs we have a system where child data is coming in for many parents every day for 100 days. With a heap table the data pours into the growing end of the table, usually a record or two per parent each day and no guarantee that if two records come in, they will be put into the same block.

So, when you select a child record for a parent you get the situation shown below:

When oracle needs to collect a record from the table, it has to read the whole block. Oracle only reads in tablespace data in whole blocks. That record comes with many other records in it that you did not ask for or want. I refer to this as Collateral Data – innocent bystander data that has got pulled into the BBC just because it was in the same block as required data. The larger the block size, the more collateral data there is.

To get all the child records for the parent, you need to read all those individual table blocks holding one or two records of interest. For our 100 child records you will probably need to read in close to 100 table blocks. Your Block Buffer Cache is filling up with of blocks where only one row out of each block is “of interest”. If that is one row out of 80 in a block, you are effectively wasting 98.75% of the space that table takes up in the block buffer cache .