patrick.dowler at nrc-cnrc.gc.ca
Tue Mar 17 13:18:28 PDT 2009
The TAP spec currently specifies metadata (needed to write queries) in several
TAP_SCHEMA is an information-schema-like approach where the service provides
standard "tables" containing metadata about other tables.
VOSI-tables is a way to request an XML description of all the database content
from the service. This same metadata (VODataService format) could be
available (whole or partially) in a registry.
Tableset query: this returns a complete description like VOSI-tables (same
format?) and in future might allow for conditions so that one got a portion
of the metadata. I will admit that I do not understand the motivation for
The content of the metadata in TAP_SCHEMA and VODataService is supposed to be
(must be?) the same or else one or both of them will be insufficient. They
currently allow one to describe a schema(ta), table(s), and column(s) but
not functions (needed to use ADQL region) and does not describe keys and/or
how to do joins between tables.
What is the minimum that we need for TAP to be useful? What is missing?
PS-please comment with respect to the recently posted TAP 0.41 (content
unchanged since 0.3 but page/section numbering has changed)
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