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 feed_the_future_malawi_baseline_household_survey table in this repository, by referencing it like:
"datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latest"."feed_the_future_malawi_baseline_household_survey"or in a full query, like:
SELECT
":id", -- Socrata column ID
"zia_supervisor_cd", -- ZIA Supervisor cd
"a02", -- ZIA Cluster cd
"zid_toilet_tp_oth_sp", -- ZID Toilet tp oth sp
"zid_ext_wall_tp_oth_sp", -- ZID Ext wall tp oth sp
"modd_missing", -- Missing all elements from D
"f05", -- ZIF Whl day no eat yn
"d06", -- ZID Drink water src
"d05", -- ZID Toilet tp
"urbrur", -- Urban Rural 1 urban 2 rural
"zid_fuel_src_oth_sp", -- ZID Fuel src oth sp
"zid_fuel_src_2", -- ZID Fuel src 2
"zid_roof_tp_oth_sp", -- ZID Roof tp oth sp
"a21", -- Interview outcome derived by module C data
"d04", -- ZID Rooms num
"d03", -- ZID Ext wall tp
"f03", -- ZIF Sleep hungry yn
"hh_size", -- HouseHold Size
"d02", -- ZID Floor tp
"modf_missing", -- Missing all elements from F
"zid_drink_water_src_other", -- ZID Drink water src other specify
"hhhunger", -- Moderate or Severe HH Hunger
"d01", -- ZID Roof tp
"country", -- ZIA Country
"zi_start_dt", -- ZI Start DT
"zia_visit2_rsn", -- ZIA Visit2 rsn
"zia_visit2_dt", -- ZIA Visit2 dt
"hhwght", -- Household weight
"pbs_id", -- PBS ID
"zia_visit2_yn", -- ZIA Visit2 yn
"d07", -- ZID Electr yn
"f04", -- ZIF Sleep hungry freq
"f02", -- ZIF No food freq
"zid_drink_water_src_other_1", -- ZID Drink water src other specify 2
"d08", -- ZID Fuel src
"a09", -- Household type derived by module C data
"zia_location_cd", -- ZIA Location cd
"a05", -- ZIG1 Sex g1
"f01", -- ZIF No food yn
"zid_floor_tp_oth_sp", -- ZID Floor tp oth sp
"a06", -- Household type derived by module C data
"hungerscale", -- Household Hunger Scale 0 6
"f06", -- ZIF Whl day no eat freq
"zid_electr_yn_2", -- ZID Electr yn 2
"zid_drink_water_src_2" -- ZID Drink water src 2
FROM
"datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latest"."feed_the_future_malawi_baseline_household_survey"
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 datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef with SQL in under 60 seconds.
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, 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 (like this repository), where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Cloning Data
Because datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latest is a Splitgraph Image, you can clone the data from Spltgraph Cloud to your local engine, where you can query it like any other Postgres database, using any of your existing tools.
First, install Splitgraph if you haven't already.
Clone the metadata with sgr clone
This will be quick, and does not download the actual data.
sgr clone datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaefCheckout the data
Once you've cloned the data, you need to "checkout" the tag that you want. For example, to checkout the latest tag:
sgr checkout datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latestThis will download all the objects for the latest tag of datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef and load them into the Splitgraph Engine. Depending on your connection speed and the size of the data, you will need to wait for the checkout to complete. Once it's complete, you will be able to query the data like you would any other Postgres database.
Alternatively, use "layered checkout" to avoid downloading all the data
The data in datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latest is 0 bytes. If this is too big to download all at once, or perhaps you only need to query a subset of it, you can use a layered checkout.:
sgr checkout --layered datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef:latestThis will not download all the data, but it will create a schema comprised of foreign tables, that you can query as you would any other data. Splitgraph will lazily download the required objects as you query the data. In some cases, this might be faster or more efficient than a regular checkout.
Read the layered querying documentation to learn about when and why you might want to use layered queries.
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, datahub-usaid-gov/feed-the-future-malawi-baseline-household-survey-a4ce-qaef is just another Postgres schema.