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Data Format in the polyDB
MongoDB Structure
MongoDB stores data in collections orgenized in databases (so the structure has two levels). There is one special database admin
for user information, permissions and passwords.
The polyDB
uses two databases inside a MongoDB instancs: Data is stored in the database polyDB
. Users and permissions are stored in admin
.
polyDB Structure
A objects are stored in collections, and collections can be organized in (nested) sections. For each data collection there is an accompanying collection containing meta information on the data.
A family of objects (a collection in polyDB
language) collection organized in the subsection sub of section section is stored in the MongoDB collection section.sub.collection
. The meta information is in _collectionInfo.section.sub.collection
. For example, the family of smooth reflexive polytopes is in the collection SmoothReflexive
in the subsection Lattice
of the section Polytopes
. In polyDB
the data is contained in the MongoDB collection Polytopes.Lattice.SmoothReflexive
, and the meta information is in _collectionInfo.Polytopes.Lattice.SmoothReflexive
.
Any documentation for the sections and collections is in the collection _collectionInformation.section.sub.collection
and _sectionInfo.section
, _sectionInfo.section.sub
etc.
Data in the data collection is described by two documents in the mata collection:
- a document for meta information. This document should have the following entries
description
: A short description of the datamaintainer
: Maintainer of the data in polyDBcreator
: Name of person creating the datacontributor
: Name of the person who prepared the data for inclusion onto polyDBfields
: A list of data fields contained in a document in the collection. This can be used to produce a list of data that can be queried from the collection.polydb_version
: the version of polyDB used to store the datapackages
: Here software packages can store additional information they need to access the data
- a json schema: A json schema that completely describes the data. Each document in the collection should verify against this schema. MongoDB comes with its own internal schema verification methods. However, in
polyDB
we do not use this as it is based on an old draft of the schema language and has modifications from the standard. The schema is stored in a schema document with the three entriessection
: the section of the collection the schema applies tocollection
: the collection the schema applies toschema
: The actual json schema. Both json schemas and MongoDB use$
as a special character. We need to replace this in the schema for stroring as this would lead to conflicts otherwise. InpolyDb
we use__
(two underscores) for this.
The MongoDB _id
of the info document is info.<polydb version>
and of the schema document schema.<polydb version>
, where <polydb version.
is the polydb version number for which the two documents apply.