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Tangram::Sucks(3)     User Contributed Perl Documentation    Tangram::Sucks(3)

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.

perl v5.32.1			  2015-10-09		     Tangram::Sucks(3)

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