Exact match, variant and candidate substitute: three relationships to keep apart

Most catalog matching problems come from one word doing three jobs. “Match” is used to mean these two records describe the same product, these two products are closely related versions of each other, and this product could be used instead of that one. Those are different claims with different evidence requirements and different consequences when they are wrong.

This comparison sets out the three relationships, what each requires and the common mistakes that collapse them.

The three relationships

In the MyBearings draft record envelope these map to relationship types same_identity_candidate, variant and candidate_substitute, each with a status of proposed, reviewed or rejected and a list of source IDs.

Exact identity

Identity is manufacturer plus full designation. The full designation includes prefixes and suffixes that change the product: closure, clearance, cage, precision class, lubrication and similar configuration markers. What each suffix means differs between manufacturers, so a suffix should be interpreted with its manufacturer’s documentation, not by a cross-brand lookup.

Two records are an exact identity candidate when, after normalization of formatting only, manufacturer and full designation agree. Formatting normalization means things like case, whitespace, and separator characters, and only where the manufacturer’s convention says they are not meaningful.

Illustrative, synthetic values:

The third row is not an exact match even though it shares a base. It may be the open version, or it may be a supplier that truncated the designation. The record must stay unresolved until evidence decides which.

Variant

A variant shares a base design with another product but differs in a configuration that matters to the buyer. Open versus sealed, different internal clearance, different cage material: each produces a different product with its own identity.

Variants should be linked so users can navigate between them, and kept separate so stock, pricing and specifications never merge. A good test: if shipping one instead of the other would generate a return or a complaint, they are variants, not duplicates.

Candidate substitute

A candidate substitute is a product from the same or another manufacturer that has been compared against a reference product on a stated set of attributes. The word candidate is deliberate. Matching published dimensions and configuration supports a shortlist; it does not establish that one product can replace another in a specific application. Load ratings, speed limits, materials, tolerances, lubrication and application conditions can all matter, and some of them may not be published consistently.

A responsible substitute record lists:

• the attributes compared and their values on both sides,
• the attributes that differ,
• the attributes that could not be compared because evidence was missing,
• the source and date for each value,
• who or what proposed it, and whether anyone qualified has reviewed it.

Negative examples

These are the patterns that cause most false merges. Illustrative, synthetic values.

Identification is not interchangeability

Part identification connects a record to a manufacturer product and documents the evidence and uncertainty. It answers “what is this?” It does not answer “can I use this instead?” Systems and interfaces should keep the two questions visibly separate. A resolver that returns a substitute when asked for an identity, or that hides missing comparison fields, creates risk for everyone downstream.

How to store decisions

• Never merge records destructively on a proposed match. Link them, and keep the originals.
• Record relationship type, status, evidence and reviewer for every accepted link.
• Allow rejection. A rejected candidate is useful information that prevents the same false match from being proposed again.
• Re-evaluate when source data changes, such as a designation being superseded.

Apply it

• Find exact duplicate candidates in your file with the local catalog checker. It groups rows by manufacturer and full designation for review; it never merges them.
• See the relationship types in the draft bearing record schema.
• Read about matching and deduplication and part identification, or discuss your catalog.