Query the Data Delivery Network
Query the DDNThe easiest way to query any data on Splitgraph is via the "Data Delivery Network" (DDN). The DDN is a single endpoint that speaks the PostgreSQL wire protocol. Any Splitgraph user can connect to it at data.splitgraph.com:5432 and query any version of over 40,000 datasets that are hosted or proxied by Splitgraph.
For example, you can query the development_log_historical_projects_additional table in this repository, by referencing it like:
"cambridgema-gov/development-log-historical-projects-additional-5432-hmix:latest"."development_log_historical_projects_additional"or in a full query, like:
SELECT
":id", -- Socrata column ID
"latlong_zip",
"developer", -- Initially the applicant, the developer may change if ownership of the property changes.
"total_gfa", -- Total gross floor area (GFA) for all uses included in project under development as defined by the zoning ordinance. Other gross floor area may exist on the parcel either in existing or prospective buildings that affects the floor-to-area ratio (FAR).
"use_type", -- Largest proportion of GFA by land use is primary use. For more detail see the associated Project Use Data table.
"latlong_address",
"longitude",
"total_of_units", -- Number of permitted residential units included in project including new construction and those in rehabbed structures. Blank value indicates nonresidential project.
"far", -- Floor-to-Area (FAR) ratio, which is ratio of Total Gross Floor Area (GFA) to Lot Area. Other GFA not included in the project may exist on the parcel either in existing or prospective buildings that affects the FAR. See Note field for additional information about FAR in some cases.
":@computed_region_rcj3_ccgu",
"of_affordable_units", -- Number of residential units with affordability restrictions. Includes units qualified through all affordability programs. TBD indicates that the project will include a yet to be determined number of affordable units. None indicates that no affordable units are included in project.
":@computed_region_v7jj_366k",
":@computed_region_guic_hr4a",
"lot_area", -- Includes land area of all parcels or property included in project.
"building_permit", -- Only projects with a status of Building Permit Granted or Complete list building permit numbers. In cases of multiple building permits issued for a project either first or primary number listed.
"zoning", -- Primary zoning category under which the project receives(d) permits.
"permit_type", -- Refers to the primary type of development approval required from the City of Cambridge. Options include Planning Board Special Permit, As of Right, Board of Zoning Appeal, Comprehensive Permit, and large Project Review.
"project_type", -- Refers to the type of construction called for by the project. Options include addition, alteration, change of use, master plan, and new construction.
"street_name",
"latlong_state",
"latlong_city",
":@computed_region_swkg_bavi",
":@computed_region_rffn_qbt6",
"latlong", -- Latitude and longitude used to map project location. Determined using ArcGIS.
"latitude",
"address", -- Primary street address of project. The street address of a project may change once a land subdivision takes place or an official address is assigned by the City of Cambridge.
"project_name", -- Refers to a name generally used to refer to the project. Not all projects have names.
"prior_site_name", -- Prior name by which site was know, if applicable.
"hotelrooms", -- Blank value indicates project without hotel use.
"year_complete", -- Refers to the year in which a Certificate of Occupancy is granted.
"neighborhood", -- Cambridge is divided into thirteen neighborhoods. For more information see http://www.cambridgema.gov/CDD/planud/neighplan.aspx
"projectid",
"pb_special_permit", -- Permit number from Planning Board proceedings, if applicable. Not all projects require Planning Board approval.
"status", -- Refers to the project stage. Options are Permitting, Permit Granted or As of Right, Building Permit Granted, and Complete. See metadata for further details.
"street_number",
"parking_spaces", -- Includes only on site spaces assigned to uses found in the project. In some case parking is shared with other developments or is located off site. In some instances parking for other nearby uses is located on site. In these cases information about total parking found on the project parcel is stated in the Notes field.
"note" -- Explanatory notes about parking arrangements, computation of FAR, project phasing, and other pertinent topics.
FROM
"cambridgema-gov/development-log-historical-projects-additional-5432-hmix:latest"."development_log_historical_projects_additional"
LIMIT 100;Connecting to the DDN is easy. All you need is an existing SQL client that can connect to Postgres. As long as you have a SQL client ready, you'll be able to query cambridgema-gov/development-log-historical-projects-additional-5432-hmix with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.cambridgema.gov. When you querycambridgema-gov/development-log-historical-projects-additional-5432-hmix:latest on the DDN, we "mount" the repository using the socrata mount handler. The mount handler proxies your SQL query to the upstream data source, translating it from SQL to the relevant language (in this case SoQL).
We also cache query responses on the DDN, but we run the DDN on multiple nodes so a CACHE_HIT is only guaranteed for subsequent queries that land on the same node.
Query Your Local Engine
bash -c "$(curl -sL https://github.com/splitgraph/splitgraph/releases/latest/download/install.sh)"Read the installation docs.
Splitgraph Cloud is built around Splitgraph Core (GitHub), which includes a local Splitgraph Engine packaged as a Docker image. Splitgraph Cloud is basically a scaled-up version of that local Engine. When you query the Data Delivery Network or the REST API, we mount the relevant datasets in an Engine on our servers and execute your query on it.
It's possible to run this engine locally. You'll need a Mac, Windows or Linux system to install sgr, and a Docker installation to run the engine. You don't need to know how to actually use Docker; sgrcan manage the image, container and volume for you.
There are a few ways to ingest data into the local engine.
For external repositories (like this repository), the Splitgraph Engine can "mount" upstream data sources by using sgr mount. This feature is built around Postgres Foreign Data Wrappers (FDW). You can write custom "mount handlers" for any upstream data source. For an example, we blogged about making a custom mount handler for HackerNews stories.
For hosted datasets, where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Mounting Data
This repository is an external repository. It's not hosted by Splitgraph. It is hosted by data.cambridgema.gov, and Splitgraph indexes it. This means it is not an actual Splitgraph image, so you cannot use sgr clone to get the data. Instead, you can use the socrata adapter with the sgr mount command. Then, if you want, you can import the data and turn it into a Splitgraph image that others can clone.
First, install Splitgraph if you haven't already.
Mount the table with sgr mount
sgr mount socrata \
"cambridgema-gov/development-log-historical-projects-additional-5432-hmix" \
--handler-options '{
"domain": "data.cambridgema.gov",
"tables": {
"development_log_historical_projects_additional": "5432-hmix"
}
}'That's it! Now you can query the data in the mounted table like any other Postgres table.
Query the data with your existing tools
Once you've loaded the data into your local Splitgraph engine, you can query it with any of your existing tools. As far as they're concerned, cambridgema-gov/development-log-historical-projects-additional-5432-hmix is just another Postgres schema.