Update database span name: clarify target and remove fallback

.chloggen/1069.yaml

@@ -0,0 +1,7 @@
+change_type: enhancement
+
+component: db
+
+note: 'Update database span name: clarify that target depends on the operation and should not be set when corresponding data is not available.'
+
+issues: [1045]

docs/database/database-spans.md

@@ -62,14 +62,19 @@ If there is no (low-cardinality) `db.operation.name` available, database span na
 SHOULD be [`{target}`](#target-placeholder).
 <!-- markdown-link-check-enable -->
 
+If neither `db.operation.name` nor `{target}` are available, span name SHOULD be `db.system`.
+
 Semantic conventions for individual database systems MAY specify different span name format.
 
-The <span id="target-placeholder">`{target}`</span> SHOULD adhere to one of the following values, arranged in prioritized order, provided they are accessible:
+The <span id="target-placeholder">`{target}`</span> SHOULD describe the entity that the operation is performed against
+and SHOULD adhere to one of the following values, provided they are accessible:
+
+- `db.collection.name` SHOULD be used for data manipulation operations or operations on database collections.
+- `db.namespace` SHOULD be used only for operations on a specific database namespace.
+- `server.address:server.port` SHOULD be used for other operations not targeting any specific database(s) or collection(s)
 
-- `db.collection.name`
-- `db.namespace`
-- `server.address:server.port`
-- `db.system`
+If a corresponding `{target}` value is not available for a specific operation, the instrumentation SHOULD NOT populate `{target}`.
+For example, for an operation describing SQL query on an anonymous table `SELECT * FROM (VALUES 'a', 'b', 'c') AS t (name)`, span name should be `SELECT`.
 
 ## Common attributes