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Get an append-only event log running on your machine in under five minutes. You will install Log, start the server, append events, and read them back using curl.

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Install OpenData Log

Download and install the Log binary: 
curl https://www.opendata.dev/install.sh | sh
This places the opendata-log binary in the current directory.

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Start the server

Start Log on port 8081: 
./opendata-log --port 8081
No configuration file is needed — all options are passed as CLI flags. Data is stored in .data/ by default.

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Append records

Append three order events to the orders key. Keys and values are base64-encoded in the JSON body: 
curl -X POST http://localhost:8081/api/v1/log/append \
  -H "Content-Type: application/json" \
  -d '{
    "records": [
      {
        "key": { "value": "b3JkZXJz" },
        "value": "eyJpdGVtIjoid2lkZ2V0IiwicXR5IjozLCJwcmljZSI6OS45OX0="
      },
      {
        "key": { "value": "b3JkZXJz" },
        "value": "eyJpdGVtIjoiZ2FkZ2V0IiwicXR5IjoxLCJwcmljZSI6MjQuOTV9"
      },
      {
        "key": { "value": "b3JkZXJz" },
        "value": "eyJpdGVtIjoid2lkZ2V0IiwicXR5IjoxMCwicHJpY2UiOjkuOTl9"
      }
    ]
  }'
The key and values decode to:
Base64Plain text
b3JkZXJzorders
eyJpdGVtIjoid2lkZ2V0IiwicXR5IjozLCJwcmljZSI6OS45OX0={"item":"widget","qty":3,"price":9.99}
eyJpdGVtIjoiZ2FkZ2V0IiwicXR5IjoxLCJwcmljZSI6MjQuOTV9{"item":"gadget","qty":1,"price":24.95}
eyJpdGVtIjoid2lkZ2V0IiwicXR5IjoxMCwicHJpY2UiOjkuOTl9{"item":"widget","qty":10,"price":9.99}
The server responds with the starting sequence number and how many records were written: 
{
  "status": "success",
  "recordsAppended": 3,
  "startSequence": 0
}

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Read records back

Scan all entries for the orders key: 
curl "http://localhost:8081/api/v1/log/scan?key=orders"
The response includes each entry’s global sequence number and its base64-encoded value: 
{
  "status": "success",
  "key": { "value": "b3JkZXJz" },
  "values": [
    { "sequence": 0, "value": "eyJpdGVtIjoid2lkZ2V0IiwicXR5IjozLCJwcmljZSI6OS45OX0=" },
    { "sequence": 1, "value": "eyJpdGVtIjoiZ2FkZ2V0IiwicXR5IjoxLCJwcmljZSI6MjQuOTV9" },
    { "sequence": 2, "value": "eyJpdGVtIjoid2lkZ2V0IiwicXR5IjoxMCwicHJpY2UiOjkuOTl9" }
  ]
}
Add limit to paginate through large result sets: 
curl "http://localhost:8081/api/v1/log/scan?key=orders&limit=1"

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Explore more endpoints

List all keys in the log: 
curl "http://localhost:8081/api/v1/log/keys"
List storage segments: 
curl "http://localhost:8081/api/v1/log/segments"

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Next steps

  • Explore the full API in the API reference section in the sidebar.
  • Learn how segments and compaction work in Storage design.