An overview over the tables available for ADQL querying within the XAO Data Center
This service formats metadata for tables within the XAO Data Center
Discrete values found in string-valued columns.
This is usually filled by dachs limits. Only columns with a statistics property of "enumerate" are considered here. Values found here are
A table for storing all kinds of key-value pairs. Key starting with an underscore are for use by user RDs.
Only one pair per key is supported, newer keys overwrite older ones.
Currently, this is only used for schemaversion, the version of the DaCHS system tables as used by gavo upgrade to figure out what to change. gavo upgrade manages this.
From your code, you can use base.getDBMeta(key) and base.setDBMeta(connection, key, value) to put persistent, string-valued metadata in here; if you use this, would you tell us your use case?
Simple (one-column) statistics of orderable columns
This is usually filled by dachs limits, which might use estimates rather than actual statistics for large tables. Also, values elements on the column definitions themselves override what may be given here.
A table mapping table names and schemas to the resource descriptors they come from and whether they are open to ADQL queries.
This is used wherever DaCHS needs to go from a database name to the resource description, e.g., when generating tableinfo.
The table is maintained through gavo imp; to force things out of here, there's gavo drop (for RDs; use -f if the RD is gone or meoved away) or gavo purge (for single tables).
Please report errors and problems to the site operators. Thanks.