What makes a good XML Database?

Elliotte Rusty Harold has slides up from his recent talk on Native XML Databases to a NY PHP users group. According to ERH, here’s what to consider when investigating XML Databases:

Questions to Ask

i.e. characteristics that distinguish products

• Can a DB handle very large single documents?
• Can the DB handle very many small-to-medium documents?
• Maximum database size
• Granularity of locks: per-document or smaller?
• XQuery 1.0 support
• XQuery Full-text search support
• Update support
• Schemas: required, optional, or unsupported?
• Import formats
• XSLT support (a la FileMaker)
• And of course cost, freedom, and support