[Zope] new howto: choosing sql vs ZODB.

[Tres Seaver]

Anthony Baxter <anthony@interlink.com.au> wrote:

> At http://www.zope.org/Members/anthony/sql_vs_ZODB/ I've started to 
> put together a howto listing some of the things to think about when
> you're deciding whether to put data into the ZODB or an SQL database.
> 
> 
> feedback, additional data points welcome...
I like it!

Another point to consider is how well the data "fits" the storage model.  As an
example, in a former life I built a system storing "standard operating
procedures" into an RDBMS.  Each procedure had one or more steps, each of which
might be recursively decomposed into substeps -- they also might reference
diagrams, illustrations, and multimedia content.

Although I managed to make this work in SQL, the impedance mismatch was very
high, compared with doing it in a hierarchical database like ZODB.  RDBMS's
excel at allowing "slice and dice" queries, at the expense of requiring
expensive joins to implement parent-child links;  hierarchical DB's optimize the
parent-child relationships, making "cross-family" queries difficult or even
infeasible.

Best,

Tres.
-- 
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Tres Seaver         tseaver@palladion.com    713-523-6582
Palladion Software  http://www.palladion.com