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ADR-005 split machines from measuring tools on the grounds that they are two asset classes. It named the metrology population as CMMs, vision systems, wax trace and Genspect; the plugin was then built against a docstring naming calipers, micrometers and thread gages. Those are not the same population, and the difference is the whole decision: bay-mounted capital equipment with a controlling PC on one side, hand tools in a drawer on the other. Sixteen months on, measuringtools holds zero rows against 204 machines. The metrology inventory waiting to be entered is 134 instruments - 35 CMM, 32 form tracer, 23 vision, 18 wax, 14 measuring, 8 Genspect, 2 eddy, 1 spline - every one bay-mounted with a controlling PC, and not one hand gage among them. CMM is already a machinetype, and Part Marker is already a machine while Form Tracer is a measuring tool, so the line is already drawn somewhere no operator can predict. Retires the plugin and the measuring_tool asset type. Calibration is not lost: it moves onto machines as four nullable columns with status still derived at read, which is a gain rather than a port because a machine could not record calibration at all before. ADR-005's one concrete objection - that "show me all measuring tools" would need an enumeration of type names - is answered with machinetypes.ismetrology, so it stays a single-column filter. Taken now because measuringtools is empty. After the 134 rows are entered they carry relationships, audit history, map positions and collector links, and the migration stops being a drop. Scope: product
125 lines
5.9 KiB
Markdown
125 lines
5.9 KiB
Markdown
# ADR-018: Metrology instruments are machines
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- Status: ACCEPTED
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- Date: 2026-09-04
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- Deciders: ShopDB maintainers
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- Relates to: ADR-001 (asset as the platform contract), ADR-006 (collector
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contract), ADR-008 (a plugin owns its tables and its migration chain)
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- Supersedes: ADR-005 (equipment plugin scope vs measuringtools plugin)
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## Context
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ADR-005 split manufacturing machinery from metrology instruments into two
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plugins on the grounds that they are two asset classes: machines make parts,
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measuring tools measure them. It named the metrology population as "CMMs,
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Keyence vision systems, wax-and-trace surface profilometers, GenSpec
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instruments", and the `measuringtools` plugin was built against a docstring
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naming a different population again: "calipers, micrometers, thread gages,
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bore gages, height gages".
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Those two lists are not the same thing, and the difference is the whole
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decision. One is bay-mounted capital equipment with a controlling PC. The other
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is hand tools in a drawer. The plugin was built for the second and populated
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with neither.
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Sixteen months on, the evidence is in:
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- `measuringtools` holds **zero rows**, against 204 machines, 305 computers,
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73 network devices and 53 printers.
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- The metrology inventory actually waiting to be entered is 134 instruments:
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35 CMM, 32 form tracer, 23 vision, 18 wax trace, 14 measuring, 8 Genspect,
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2 eddy current, 1 spline. Every one is bay-mounted with a controlling PC.
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- Not one caliper, micrometer, thread gage, bore gage or height gage. The
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population the plugin's own docstring justifies it with does not exist at
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the reference site and is not planned.
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- `CMM` already exists as a `machinetype`, and `Part Marker` is already
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classed as a machine while `Form Tracer` is classed as a measuring tool.
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Two bay instruments with a controlling PC, split across two plugins, with
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the line drawn somewhere no operator can predict.
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The split has therefore been paying an ongoing cost - a duplicate type page, a
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settings group, a nav section, a migration chain, a searcher, dashboard cards,
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map colours, label printing and four collector `pctypemap` entries - to model a
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distinction that the inventory does not make.
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## Decision
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Metrology and inspection instruments are machines. The `measuringtools` plugin
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is retired and the `measuring_tool` asset type is removed.
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### Calibration moves to machines, and is not lost
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`machines` gains the calibration lifecycle as nullable columns:
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```
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machines
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- calibrationintervaldays integer, null
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- lastcalibrationdate date, null
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- nextcalibrationdate date, null
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- calibrationprovider varchar(150), null
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```
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Calibration status stays **derived at read time** from `nextcalibrationdate`
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(`overdue` / `duesoon` / `current` / `unknown`, 30-day window), exactly as
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`measuringtools` derived it and for the same reason: a stored status is stale
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the day after it is written. The helper moves across unchanged.
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This is a net gain rather than a port. A machine could not record calibration
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at all before, and a part marker with a certified fixture, or a machine with a
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calibrated probe, had nowhere to put it.
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### `machinetypes.ismetrology` answers ADR-005's objection
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ADR-005 made one concrete technical argument, and it deserves a concrete
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answer rather than silence:
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> "show me all measuring tools" requires an enumeration of measuring-instrument
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> equipmenttype values, which scales badly.
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That is correct about enumeration and it is why `machinetypes` gains a boolean
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`ismetrology`. The metrology view stays a first-class single-column filter -
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`WHERE mt.ismetrology = 1` - not a hardcoded list of type names that drifts the
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first time someone adds an instrument type. The calibration report, the gage
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lab view and any compliance export all hang off that flag.
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### What does not change
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- `assets.gaugelabreference` stays on the core asset. The gage tag was never a
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`measuringtools` column, so it survives untouched and stays searchable for
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every asset type.
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- The collector's device identity file and the `measuringtoolid` payload alias
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stay accepted. Bays staged with `measuringtool-id.txt` keep reporting; only
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the asset type they resolve to changes.
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- Instrument types keep their names. A Form Tracer is still a Form Tracer, now
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as a `machinetype` with `ismetrology = 1`.
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## Consequences
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**The migration is free today and expensive later.** `measuringtools` has zero
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rows, so retirement is a `DROP TABLE`, not a data migration. Once the 134
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staged instruments are entered they carry relationships, audit history, map
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positions and collector links, and every one of those would have to be
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rewritten. This ADR is being taken now specifically because the window is open.
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**A site that did populate it needs a real migration.** The reference site did
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not and the sister site shows no sign of having done so - its branch contains
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no deliberate work on the plugin in its entire history - but that is inference,
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not a query against their database. Confirm before the removal ships to another
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site. If rows exist, the retirement migration must copy them into `machines`
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with `ismetrology` types rather than drop them.
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**Four collector `pctypemap` entries change asset type.** `gea-shopfloor-cmm`,
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`-keyence`, `-genspect` and `-waxtrace` resolve to `machine` instead of
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`measuring_tool`. The `collector:measuringtool` relationship label is kept as a
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recognised origin marker so links a collector already created are still
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archived correctly rather than orphaned.
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**One fewer of everything.** A duplicate type page, a settings group, a plugin
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migration chain, a gated searcher, a set of dashboard cards, a map colour entry
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and a label-printing branch all go. That is the point.
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**ADR-005 is superseded, not reversed in principle.** Its reasoning was sound
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for the population it described. The population never arrived. If a site ever
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does track hand gages in quantity, the answer is a `handgages` plugin against
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that real inventory - not the reinstatement of this one.
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