PDGGK opened a new pull request, #114:
URL: https://github.com/apache/iotdb-extras/pull/114
## What
Adds table-model query support to the IoTDB Grafana data source plugin — the
first slice of #18258.
The plugin previously only spoke the tree model: both QueryEditor modes
build `root.*` paths and the backend calls `/grafana/v1/query/expression`,
which has no table-model equivalent, so table-model users could not visualize
their data.
## How
- **New QueryEditor mode "SQL: Table Model"** — a database field, a SQL
editor and a result format option, alongside the existing "SQL: Full
Customized" and "SQL: Drop-down List" modes.
- **Reuses IoTDB's existing table REST API** (`POST /rest/table/v1/query`)
instead of adding a new server endpoint — the Go backend sends `{database,
sql}` and parses the row-major `QueryDataSet`.
- **Typed, nullable fields driven by `data_types`** — TIMESTAMP → time,
INT32/INT64 → int64, FLOAT/DOUBLE → float64, BOOLEAN → bool, TEXT/others →
string — so column types are exact instead of guessed the way the tree-model
path is.
- **Multi-device results render as separate series**: in the default `Time
series` format, rows are sorted by the first TIMESTAMP column and a long-shaped
result (time + tag columns + value columns) is pivoted with the SDK's
`data.LongToWide`, turning tag columns into field labels — `SELECT time,
device_id, temperature FROM t` draws one line per device instead of one
interleaved series. The `Table` format returns rows untouched (preserves a
user's `ORDER BY`). If the pivot cannot apply (e.g. null timestamps), the plain
frame is returned.
- **`$__timeFilter(col)` / `$__timeFrom` / `$__timeTo` macros** expand to
the panel's range; the function forms `$__timeFrom()` / `$__timeTo()` familiar
from Grafana's SQL data sources are accepted too, and `$__timeFilter` allows
one level of nested parentheses.
- **Timestamp precision support**: the table REST endpoint returns TIMESTAMP
values (and compares integer time literals) in the server's configured
`timestamp_precision`, unlike the tree-model `/grafana/v1` endpoints which
normalize to ms server-side. A new data source `time precision` option (ms
default / us / ns) scales both the macro expansion and the TIMESTAMP field
rendering, so the mode works on non-ms servers. (Auto-discovery was considered
and rejected: `SHOW VARIABLES` requires the SYSTEM privilege in the table
model.)
- **`UseNumber` decoding** so INT64 values above 2^53 keep full precision.
- **README**: documents the new mode, the macros, the format option, the
precision option and the server-side row limit
(`rest_query_default_row_size_limit`).
## Testing
- Backend: `go build`, `go vet`, and `go test ./pkg/plugin` (13 unit tests)
pass — covering row-major frame building, per-type conversion, null handling,
macro expansion (including the function forms and nested parentheses), INT64
precision, us/ns timestamp rendering, the long-to-wide pivot for multi-device
results (including the unsorted-input and null-timestamp fallback paths),
Table-format row-order preservation, and error responses. The orientation and
precision tests are written to fail against an incorrect implementation.
- Frontend: type-checked with `tsc --noEmit` against the `@grafana` types.
- The request/response contract was verified against the `/rest/table/v1`
OpenAPI spec, `QueryDataSetHandler`, `RestApiServiceImpl` and
`IoTDBRestServiceIT` (row-major orientation, per-type JSON serialization incl.
DATE/BLOB/STRING, error shape, row-limit behavior, and the precision behavior
above). It has not yet been smoke-tested against a live server.
## Follow-ups (same issue)
Database → table → column browser, a visual query builder, a default row
limit to bound large `SELECT`s, path-picker performance, and the Grafana plugin
SDK / Go backend modernization (the current `@grafana/toolkit` toolchain is
deprecated).
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