A connection is a saved way to reach data you keep somewhere else: a database, a cloud warehouse, a storage bucket or a GIS service. You enter the details once and reuse the connection in your maps and flows.
What each source can do
| Source | Add a layer to a map | Read in a flow | Write from a flow |
|---|---|---|---|
| PostGIS | Yes | Yes | A table |
| SQL Server | Yes | Yes | A table |
| Amazon Redshift | Yes | Yes | A table |
| BigQuery | Yes | Yes | A table |
| Snowflake | Yes | Yes | A table |
| Databricks | Yes | Yes | A table |
| Amazon S3 | Yes | Yes | A file |
| Google Cloud Storage | Yes | Yes | A file |
| Azure Blob Storage | Yes | Yes | A file |
| ArcGIS feature service | Yes | Yes | No |
| OGC API Features or WFS | Yes | Yes | No |
| STAC catalog | Yes | Yes | No |
A layer added from a source can be refreshed by hand whenever you want the latest data, or on a schedule you set.
Create a connection
- Open "Settings", then "Connections".
- Select "Create connection".
- Choose the "Source type" and give the connection a "Connection name".
- Fill in the details for that source. Where a source offers more than one, choose a "Sign-in method".
- Select "Test connection". "Test successful." confirms that Tamaat reached the source and signed in.
- Select "Save connection".
Each source's page lists its fields and what the sign-in needs to be allowed to do:
- Databases: PostGIS, SQL Server, Amazon Redshift
- Cloud warehouses: BigQuery, Snowflake, Databricks
- Cloud storage: Amazon S3, Google Cloud Storage, Azure Blob Storage
- GIS services: ArcGIS feature services, OGC API Features, WFS, STAC catalogs
Add a layer from a connection
- In a map, add a layer and choose "Connect to source".
- Choose the "Source" and the "Connection".
- Under "Data", browse to a table, view, layer or file. For a database or a warehouse you can select "Write a query instead" and write one
SELECT. - If the data has more than one spatial column, choose the "Geometry column".
- Give the layer a "Layer name" and add it.
Tamaat copies the data into the layer. The map does not query your source each time it draws, so it stays fast and keeps working when the source is offline.
Refresh a layer from its source
Open the layer's menu and choose "Refresh from source". The dialog shows when the layer was last refreshed.
- The layer is replaced in one step. If the refresh fails or you stop it, the layer keeps the data it had.
- If you edited the layer in Tamaat, the dialog says "This layer has edits of its own". Refreshing replaces them with the source's data, so you must select "Replace the edits made here" first.
- If someone changed the layer after you opened the dialog, the refresh is refused and you are asked to try again.
- If the source now has no rows, the layer becomes empty. It is not left showing data the source no longer has.
Refresh on a schedule
In the "Refresh from source" dialog, choose how often under "Refresh automatically": "Every hour", "Every 6 hours", "Every 12 hours", "Every day" or "Every week". Choose "Off" to stop.
- A scheduled refresh uses the connection chosen in the dialog and runs as the person who set it. If that connection is deleted or can no longer sign in, the refresh does not run and the dialog says so the next time you open it.
- A scheduled refresh never replaces edits made in the layer. A layer with edits of its own is skipped until you refresh it by hand and select "Replace the edits made here".
- A refresh that fails leaves the layer as it was, and the next one runs at its usual time.
Use a connection in a flow
- "Database Reader" reads a table, a view or one query from a database or a warehouse, and one layer from a GIS service.
- "Cloud Storage Reader" reads a file from a bucket or a container.
- "Database Writer" writes the flow's result to a table: "Create a new table", "Add rows" or "Replace the table". PostGIS can also "Update matching rows, add the rest".
- "Cloud Storage Writer" writes a file to a bucket or a container.
A table is written safely. The rows first go into a temporary table beside the target, and one final step creates, replaces or adds to your table. If the write fails, is stopped or runs out of time, your table is exactly as it was. The sign-in therefore needs permission to create tables in the schema it writes to.
What to know before you connect
- Tamaat reaches your source over the internet. A database or service that only answers inside a private network cannot be reached. Allow Tamaat's outbound address in your firewall rather than opening the source to everyone.
- Coordinates are stored as longitude and latitude (WGS 84). PostGIS and Amazon Redshift convert other coordinate systems for you. SQL Server, Snowflake and Databricks cannot, so data in another system is refused with a message that names it; convert it in a query or at the source.
- A query is one read. Write a single
SELECT. Anything that changes data is refused before it is sent. - Give the sign-in only what it needs. Read access for layers and readers; permission to create tables only where a flow writes.