Get data collection history
Retrieve historical data for a specific DCI (Data Collection Item).
The server can serve data from one of three storage tiers: raw samples, hourly aggregates, or daily aggregates. The tier query parameter selects which tier to read from (default auto, which picks the densest tier whose point count fits within the server-side DataCollection.Aggregation.MaxAutoSelectPoints threshold). When the resolved tier is hourly or daily, each row carries pre-computed avg/min/max and a sampleCount of raw samples that contributed to the bucket. The function query parameter selects which value column(s) the server returns from the aggregate tables (minmax returns avg, min, and max in a single response for band rendering).
Path parameters
Object ID
DCI (Data Collection Item) ID
Query parameters
Start time for data retrieval (Unix timestamp)
End time for data retrieval (Unix timestamp)
Maximum number of data points to return
When the request resolves to the raw tier, perform on-the-fly bucketing into this many points and return avg/min/max per bucket. Ignored on hourly/daily tier reads (those already serve pre-computed buckets).
Type of historical data (0=raw, 1=processed, 2=full table, 3=raw and processed)
Storage tier to read from. auto picks the densest tier whose point count fits the server-side auto-select threshold. Explicit tiers are downgraded to raw when the requested aggregate is not available for the DCI (e.g. string DCIs, or non-TSDB targets where the per-object aggregate table has not been created yet). The actually-served tier is reported in tierServed.
Aggregation function for hourly/daily tier reads. minmax returns avg, min, and max columns in a single response, suitable for band-graph rendering. Ignored when tierServed is raw.
Response
Data collection history retrieved successfully