Re: [binarycloud-dev] Implementing version control/history

[Alex B. <en...@tu...>]

> 
> An interesting problem becomes maintaining some mechanism of storing
> unique ids which are not the primary key of a given entity table and are
> not unique.  After some high level thinking on the subject, we had
> decided to store all unique object identifiers, let's call them OID for
> short, or, keeping with bc nomenclature, EID, in a separate table from
> which any new entity creation process would request and receive a new
> EID before inserting a new entity into it's entity table.

That's interesting. In which case you _could_ just use a normal entity, and
have the actual data entity separate.

> The EID table would store the EID and the entity table.  Adding columns
> to this table allows very cool things such as locking entities (set a
> flag in the central EID table), check-in and check-out of entities, etc.

Yeah. heh. CVS in oracle!

> This versioning business will also have significant impact on the fields
> of type "pointer".  I.e. if the referred entity type is versioned, do
> you store the EID, or the actual ID from the entity's table (in order to
> point to a particular version of the entity as opposed to always
> pointing to the latest).  This, perhaps, needs to be configurable as
> well.  Using the furbee_type_id field from entity_new.xml, let's say
> that furbee_types are versioned - because Furbees, Inc. routinely
> changes type definitions, and a given instance of a furbee's type should
> never change.  In this case, we want to always point to the same version
> of the type.
> 
> [ *snip* ]
> <field>
>           <name>furbee_type_id</name>
>           <label>Furbee type ID</label>
>           <desc>The id of the type of furbee</desc>
>           <path>furbee_type_id</path>
>           <required>true</required>
>           <type>
>               <dbtype>int</dbtype>
>               <!--
>               note the "pointer" type
>               this field is a pointer to another entity, and a
>               foreign key in the database.
>               -->
>               <type>versioned_pointer</type>
>    <!--
> If we had parameters in the XML definition, we could do
> something like:
> <type param="versioned">pointer</type> - to keep from
> creating too many
> like types which have only minor variations.
>    -->
>               <!--
>               form above, the entity name to use for requesting
>               data from this pointer
>               -->
>               <entity>furbee_type</entity>
>               <maxlength>20</maxlength>
>               <format>/[\w\s_\-\.]{0,20}/</format>
>           </type>
> </field>
> [ *snip* ]

yes, though I think I'd want to have that "versioned" flag be part of the
top-level entity definition.

...

_a