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 federated_water_quality_monitoring_station_data table in this repository, by referencing it like:
"pa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x:latest"."federated_water_quality_monitoring_station_data"or in a full query, like:
SELECT
":id", -- Socrata column ID
"method_qualifier_type_name", -- Identifier of type of method that identifies it as reference, equivalent, or other.
"zip_code", -- Zip Code of the monitoring location
"location", -- The combined latitude and longitude of the monitoring location.
"detection_quantitation_limit_measure", -- Constituent concentration that, when processed through the complete method, produces a signal that is statistically different from a blank.
"result_method_identifier", -- The identification number or code assigned by the method publisher.
"result_measure_unit_code", -- The code that represents the unit for measuring the chemical substance, microbiological substance or other characteristic.
"characteristic_name", -- The object, property, or substance which is evaluated or enumerated by either a direct field measurement, a direct field observation, or by laboratory analysis of material collected in the field.
"activity_start_date", -- The calendar date on which the field activity was started.
"huc_8_digit_code", -- The 8 digit federal code used to identify the hydrologic unit of the monitoring location to the cataloging unit level of precision.
"monitoring_location_description", -- Text description of the monitoring location.
"longitude", -- The measure of the angular distance on a meridian east or west of the prime meridian.
"horizontal_coordinate_system_datum_name", -- The name that describes the reference datum used in determining latitude and longitude coordinates.
"result_method_description", -- A brief summary that provides general information about the method.
"result_method_name", -- The title that appears on the method from the method publisher.
"result_measure_value", -- The reportable measure of the result for the chemical, microbiological or other characteristic being analyzed.
"result_sample_fraction", -- The text name of the portion of the sample associated with results obtained from a physically-partitioned sample.
"time", -- The time of day that is reported.
"activity_identifier", -- Designator that uniquely identifies an activity within an organization.
"monitoring_location_name", -- The designator specified by the sampling organization for the site at which sampling or other activities are conducted. Free text name assigned to the Monitoring Location by the Trading Partner.
"result_particle_size_basis", -- User defined free text describing the particle size class for which the associated result is defined.
"county_code", -- A code designator used to identify a U.S. county or county equivalent.
"activity_type_code", -- The text describing the type of activity.
"monitoring_location_identity", -- A designator used to describe the unique name, number, or code assigned to identify the monitoring location.
"location_zip",
"location_state",
"location_city",
"location_address",
"latitude", -- The measure of the angular distance on a meridian north or south of the equator.
"detection_quantitation_limit_measure_unit", -- The code that represents the unit for measuring the chemical substance, microbiological substance or other characteristic.
"time_zone", -- The time zone for which the time of day is reported. Any of the longitudinal divisions of the earth's surface in which a standard time is kept.
"detection_quantitation_limit_type", -- Text describing the type of detection or quantitation limit used in the analysis of a characteristic.
"result_detection_condition", -- The textual descriptor of a result.
"state_code", -- A code designator used to identify a principal administrative subdivision of the United States, Canada, or Mexico.
":@computed_region_r6rf_p9et",
":@computed_region_rayf_jjgk",
":@computed_region_d3gw_znnf",
":@computed_region_nmsq_hqvv",
":@computed_region_amqz_jbr4",
"monitoring_location_type_name" -- The descriptive name for a type of monitoring location.
FROM
"pa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x:latest"."federated_water_quality_monitoring_station_data"
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 pa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.pa.gov. When you querypa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x: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.pa.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 \
"pa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x" \
--handler-options '{
"domain": "data.pa.gov",
"tables": {
"federated_water_quality_monitoring_station_data": "vna2-gb3x"
}
}'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, pa-gov/federated-water-quality-monitoring-station-data-vna2-gb3x is just another Postgres schema.