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What it is

Bigmetadata comprises four parts:

ETL | Observatory | Metadata | Catalog

Everything is dockerized and can be run on a standalone EC2 instance provided
Docker is available.

  • ETL: Luigi tasks that extract data from anywhere on the web, transform the
    data in modular and observable steps, generate metadata, and upload
    observatory datasets in the process. While the ETL pushes transformed
    datasets to CartoDB, it actually is backed by its own separate
    Postgres/PostGIS database.

  • Observatory: transformed and standardized datasets living on a CartoDB
    . This is where we can pull our
    actual data from, whether shuffling bytes or using PL/Proxy. This is also
    where preview visuals using widgets or other Carto JS interfaces can get
    their underlying data from.

  • Metadata: human and machine-readable descriptions of the data in the
    observatory. Table schema can be found in
    There are six related tables, obs_table, obs_column_table, obs_column,
    obs_column_tag, obs_tag, and obs_column_to_column. An overarching
    denomralized view can be found in obs_meta.

  • Catalog: a static HTML guide to
    data in the observatory generated from the metadata. Docs are generated
    using Sphinx and hosted on GitHub pages.




Most of the common tasks have already been wrapped up in the Makefile.

  • make catalog: Regenerate the catalog
  • make pdf-catalog: Regenerate the PDF version of the catalog
  • make deploy-catalog: Deploy the catalog to Github Pages. This will also
    rebuild both the HTML and PDF catalogs
  • make acs: ETL the entirety of the American Community Survey (Census)
  • make tiger: ETL the boundary files of the census
  • make sh: Drop into the bigmetadata container to run shell scripts
  • make python: Drop into an interactive Python shell in the bigmetadata
  • make psql: Drop into an interactive psql session in the bigmetadata
    container's database
  • make sync: Sync local data and metadata to the Observatory account.

Any other task can be run using docker-compose:

docker-compose run bigmetadata luigi --module \
  TaskName --param1 val1 --param2 val2

Or, more conveniently, make -- run (which will use the local scheduler):

make -- run TaskName --param1 val1 --param2 val2

For example, to run QCEW numbers for one quarter:

make -- run us.bls QCEW --year 2014 --qtr 4

Naming conventions


In bigmetadata's postgres, tables live in the observatory schema, with an
auto-generated hash for the tablename prefixed by obs (EG obs_<hash>).
In obs_table, the table ID refers back to the task which created that table
as well as the parameters called.


Column IDs in metadata are fully-qualified, like tables, such as
us.bls.avg_wkly_wage_trade_transportation_and_utilities. In tables
themselves, column names are the colname from metadata,
so the above would be avg_wkly_wage_trade_transportation_and_utilities in
an actual table.


Why favor descriptions of columns over tables in metadata?

Our users need third party data in their maps to make it possible for them to
better interpret their own data.

In order to make this as simple as possible, we need to rethink the prevailing
model of finding external data by where it's sourced from. Instead, we should
think of finding external data by need.

For example, instead of requiring our user to think "I need race or demographic
data alongside my data, I'm in the US, so I should look at the census", we
should enable our user to look up race or demographic data -- and figure out
which columns they need from the census without particularly worrying about
delving into the source.

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