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