[development] Database / SQL future thoughts

[Chris Johnson]

At first, the descriptions of CouchDB and Tokyo Cabinets sounded
suspiciously like multivalued databases, such as Reality and UniVerse
(both circa 1970).

CouchDB is a RESTful web service package, which has a storage engine
that uses MVCC (Postgres, Oracle, InnoDB), and b-tree indexes (used by
most RDBMSs), with sequence ids (supported by most RDBMSs).  So,
really comparing CouchDB to MySQL or Postgres is to compare apples and
baked tarts made with apples.

The Tokyo Cabinet SourceForge project says:  "Tokyo Cabinet is a
library of routines for managing a database. The database is a simple
data file containing records, each is a pair of a key and a value.
Every key and value is serial bytes with variable length. Both binary
data and character string can be used as a key and a value. There is
neither concept of data tables nor data types. Records are organized
in hash table, B+ tree, or fixed-length array.

As for database of hash table, each key must be unique within a
database, so it is impossible to store two or more records with a key
overlaps."

A blog writer says:  "Tokyo Cabinet is a simple, small, fast key/value
store. Similar to DBM, it’s a very basic database. If you combine it
with Tokyo Tyrant, it becomes a very capable, scalable network
database (like mysql or couchdb)."

So, is CouchDB's storage engine any more performant in a flexible CMS
situation like Drupal than SQL storage engines?  That remains to be
seen.  There's no obvious reason why it should be, since it does
pretty much everything an RDBMS does (indexing, ACID compliance,
etc.).

CouchDB does provide some extras which could be useful, such as the
built-in views already mentioned.  And its document orientation might
be great for large files (images, documents, etc.).  Would the RESTful
API be an advantage over SQL?

And Tokyo Cabinets -- hmmm.  Serialized data versus structured data
and database wide unique keys.  DBM primitives?  Again, it remains to
be seen whether it's faster than an SQL engine when combined with
something like Tokyo Tyrant to provide the needed concurrency
capabilities.

..chris