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 chicago_public_schools_high_school_progress_report table in this repository, by referencing it like:
"cityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f:latest"."chicago_public_schools_high_school_progress_report"or in a full query, like:
SELECT
":id", -- Socrata column ID
"average_score_explore_2012",
"average_score_plan_2012",
"average_days_of_suspension_2011", -- Average length of suspensions, in days, divided by the number of suspensions.
"x_coordinate",
"involved_families", -- Does the school partner with families and communities? For more information, visit https://cps.5-essentials.org/2012.
"healthy_school_certified", -- Is the school certified by the USDA’s Healthier US School Challenge?
"location_address",
"location_zip",
"location_city",
"blue_ribbon_award_year", -- Year in which the school won a U.S. Department of Education Blue Ribbon.
":@computed_region_awaf_s7ux",
"city",
"average_days_of_suspension_2012", -- Average length of suspensions, in days, divided by the number of suspensions.
"state",
"overall_foundation", -- Overall status from the "My Voice, My School" survey completed by teachers and 6th-12th grade students. For more information, visit https://cps.5-essentials.org/2012.
"managed_by_network",
"geographic_network",
"ambitious_instruction", -- Is instruction focused, challenging, and engaging? For more information, visit https://cps.5-essentials.org/2012.
"street_address",
"location_state",
":@computed_region_6mkv_f3dw",
":@computed_region_rpca_8um6",
":@computed_region_vrxf_vc4k",
"school_track", -- Which schedule. See http://www.cps.edu/calendar/Pages/Calendar.aspx.
"overall_rating", -- The Overall Rating on the school progress report is based on the school’s rating under the 2012-2013 Performance, Remediation and Probation Policy. Level 1 is highest.
"on_probation", -- Is the school on probation?
"growth_overall_level", -- Student growth compared to similar schools nationally
"over_time_plan_2011",
"_5_year_cohort_graduation_rate_2011_percent",
"location",
":@computed_region_43wa_7qmu",
"school_id",
"school_short_name",
"school_name",
"zip",
"website",
"growth_explore",
"growth_plan",
"growth_act",
"freshman_on_track_to_graduate_2011_percent",
"growth_all_grades",
":@computed_region_bdys_3d7i",
"collaborative_teachers", -- Do teachers work well together and strive for excellence? For more information, visit https://cps.5-essentials.org/2012.
"safety", -- Do students feel safe and does the school support positive behavior? For more information, visit https://cps.5-essentials.org/2012.
"average_score_act_2012",
"longitude",
"over_time_explore_2010",
"over_time_act_2012",
"_5_year_cohort_graduation_rate_2012_percent",
"one_year_dropout_rate_2011_percent",
"one_year_dropout_rate_2012_percent",
"years_on_probation", -- How many years has the school been on probation?
"freshman_on_track_to_graduate_2012_percent",
"college_eligibility_2011_percent",
"college_eligibility_2012_percent",
"student_performance_level",
"college_enrollment_2011_percent",
"college_enrollment_2012_percent",
"college_retention_2009_percent",
"college_retention_2010_percent",
"misconducts_resulting_in_suspensions_2011_percent", -- Number of misconducts resulting in suspension divided by the number of misconducts reported.
"misconducts_resulting_in_suspensions_2012_percent", -- Number of misconducts resulting in suspension divided by the number of misconducts reported.
"student_attendance_2011_percent", -- Average daily attendance of students -- the number of days in which students were present divided by the number of days in which students were scheduled to attend.
"student_attendance_2012_percent", -- Average daily attendance of students -- the number of days in which students were present divided by the number of days in which students were scheduled to attend.
"teacher_attendance_2011_percent", -- Average daily attendance of teachers -- the number of days in which teachers were present divided by the number of days they were scheduled to work.
"teacher_attendance_2012_percent", -- Average daily attendance of teachers -- the number of days in which teachers were present divided by the number of days they were scheduled to work.
"blue_ribbon_award", -- Did the school win a U.S. Department of Education Blue Ribbon? See http://www2.ed.gov/programs/nclbbrs/index.html.
"y_coordinate",
"latitude",
"effective_leaders", -- Does leadership focus on results and school improvement? For more information, visit https://cps.5-essentials.org/2012.
"supportive_environment" -- Is the school safe and supportive with high expectations? For more information, visit https://cps.5-essentials.org/2012.
FROM
"cityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f:latest"."chicago_public_schools_high_school_progress_report"
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 cityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.cityofchicago.org. When you querycityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f: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.cityofchicago.org, 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 \
"cityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f" \
--handler-options '{
"domain": "data.cityofchicago.org",
"tables": {
"chicago_public_schools_high_school_progress_report": "qemx-3d9f"
}
}'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, cityofchicago/chicago-public-schools-high-school-progress-report-qemx-3d9f is just another Postgres schema.