Re: Flat Query

"David Cressey" <david.cressey_at_earthlink.net> writes:
> Only if the record's addresses could be computed (or pointed to).
> In general, the only kinds of unindexed files whose record address
> was computable were fixed length records. And in general, fixed
> lentgth records corresponded to flat files.
>
> Sure you can come up with exceptions. But i'm describing the
> general scenario in which that language gained usage.

it was also somewhat the battle in the 70s that went on between the stl 60s physical database people ... and the sjr system/r people ... original relational/sql
http://www.garlic.com/~lynn/subtopic.html#systemr

i.e. the phsycial database ... had records linked to other records ... where the linking was done by physical record pointers that were fields that were part of the record data ... these weren't traditional flat file ... but record location semantics was exposed.

one of the points of system/r effort was to abstract away the reoord pointers ... by using indexing. the stl people claimed that system/r doubled the physical disk space (for the indexes) along with significant increase in processing overhead ... associated with all the index processing gorp. the sjr people claimed that system/r eliminated a lot of human effort that went into administrative and rebuilding efforts associated with the embedded record pointers. I did some of the system/r code ... but i also did some of the code for various other projects ... so I wasn't particularly on one side or anther.

the 80s saw 1) big demand increase for online information ... putting pressure on scarce database people resources, 2) significant increase in physical disk space and decrease in price/bit, and 3) large increase in processor memory that could be used for caching indexes.

The disk technology change drastically reduced the perceived cost of the extra index structures ... and the significant processor memory increses allowed significant caching ... which in turn reduced the perceived overhead of index processing.

-- 
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/