Add a SQL span naming suggestion: <db.operation> <db.name>.<db.sql.table>

[mateuszrzeszutek]

Fixes #1139

Changes

Add a suggestion that <db.operation> <db.name>.<db.sql.table> may be used for SQL DB spans; also modify the MySQL example to reflect that.

Related issues:

• SQL Normalizer should allow normalizing IN queries  opentelemetry-java-instrumentation#1409

Related oteps: none

[iNikem]

@mateuszrzeszutek Just to clarify: your intention is that both old-way "normalized" sql AND <db.operation> <db.name>.<db.sql.table> are OK ?

[mateuszrzeszutek]

your intention is that both old-way "normalized" sql AND <db.operation> <db.name>.<db.sql.table> are OK ?

Hmm, I think that the whole DB span naming spec is vague intentionally and it doesn't make any sense to say "but SQL MUST be named this way". I believe that we should at the very least recommend this low-cardinality naming scheme -- so I changed MAY to RECOMMENDED.

[Oberon00]

Note that RECOMMENDED is defined to mean the same as SHOULD and we usually use the latter: https://github.com/open-telemetry/opentelemetry-specification#notation-conventions-and-compliance

[mateuszrzeszutek]

Note that RECOMMENDED is defined to mean the same as SHOULD and we usually use the latter: https://github.com/open-telemetry/opentelemetry-specification#notation-conventions-and-compliance

Right, a quick search has revealed that RECOMMENDED is hardly ever used in this project. Changed to SHOULD.