bionic (3) Tangram::Sucks.3pm.gz

NAME

       Tangram::Sucks - what there is to be improved in Tangram

DESCRIPTION

       Tangram has taken a concept very familiar to programmers in Java land to its logical completion.

       This document is an attempt by the coders of Tangram to summarise the major problems that are inherant in
       the design, describe cases for which the Tangram metaphor does not work well, and list long standing TO-
       DO items.

   DESIGN CAVEATS
       query language does not cover all SQL expressions
           Whilst there is no underlying fault with the query object metaphor per se, there are currently lots
           of queries that cannot be expressed in current versions of Tangram, and adding new parts to the
           language is not easy.

       some loss of encapsulation with queries
           It could be said this is not a problem.  After all, adding properties to a schema of an object is
           akin to declaring them as "public".

           Some people banter on about data access patterns, which the Tangram schema represents.  But OO terms
           like that are usually treated as buzzwords anyway.

   HARD PROBLEMS
       partial column select
           This optimisation has some serious dangers associated with it.

           It could either be

       no support for SQL UPDATE
           It may be possible to write a version of "$storage->select()" that does this, which would look
           something like:

             $storage->update
                 ( $r_object,
                   set => [ $r_object->{bar} == $r_object->{baz} + 2 ],
                   filter => ($r_object->{frop} != undef)
                 );

       no explicit support for re-orgs
           The situation where you have a large amount of schema reshaping to do, with a complex enough data
           structure can turn into a fairly difficult problem.

           It is possible to have two Tangram stores with different schema and simply load objects from one and
           put them in the other - however the on-demand autoloading combined with the automatic insertion of
           unknown objects will result in the entire database being loaded into core if it is sufficiently
           interlinked.

       replace SQL expression core
           The whole SQL expression core needs to be replaced with a SQL abstraction module that is a little
           better planned.  For instance, there should be placeholders used in a lot more places where the code
           just sticks in an integer etc.

       support for `large' collections
           Where it is impractical or undesirable to load all of a collection into memory, when you are adding a
           member and then updating the container, it should be possible to do this without loading the entire
           collection into memory.

           This could actually be achieved with a new Tangram::Type.

   MISSING FEATURES
       concise query expressions
           For simple selects, the query syntax is too long.  Getting remote objects should take less code.

       non-ID joins
           We can't join on anything but "ID" values

       tables with no primary key
           We can't map tables unless they have a primary key, and it is called "id" (or, at least, the same
           name as the rest of the schema).

       tables with multi-column primary keys
           We can't map tables when they have multiple primary keys.  Well, you can, but only if you make a view
           with an ID column which is functionally derived from the multi-part keys.  But that sucks.

       tables with auto_increment keys
           These suck, but Tangram could still support them without requiring schema hacks.

       tables without a `type' column
           The 'type' column is unneeded for base tables which do not have sub-classes.

       tables with custom `type' columns
           For mapping schemata where some clever person has invented their own special way of representing
           types using discrete column values.

       tables with implicit (presence) `type' columns
           It should be possible to infer the type value based on knowledge of the schema, and the tables which
           have rows.

       fully symmetric relationships
           back-refs are read-only.

       bulk inserts
           Inserting lots of similar objects should be more efficient.  Right now it generates a new DBI
           statement handler for each object.

       `empty subclass' schema support
           You should not need to explicitly add new classes to a schema if a superclass of them is already in
           the schema.

       warn about column redefinitions
           Defining a column twice should be an error.  Reported by Mark Lawrence.