Unify vector selector queries

[mkysel]

Unify vector selector queries by updating DBBasedCursorUpdater.read to use queries.SelectVectorClock and map OriginatorNodeID to OriginatorSequenceID

The cursor updater switches to the vector clock query and aligns sequence mapping to originator values, and the SQL layer removes the latest cursor query while changing sequence selection to read from the latest table via COALESCE.

• Update DBBasedCursorUpdater.read to call queries.SelectVectorClock and map OriginatorNodeID to OriginatorSequenceID in cursor_updater.go
• Remove GetLatestCursor named query and generated accessors in envelopes.sql.go
• Modify GetLatestSequenceId to COALESCE((SELECT originator_sequence_id FROM gateway_envelopes_latest WHERE originator_node_id = @originator_node_id), 0)::BIGINT in envelopes.sql

📍Where to Start

Start with DBBasedCursorUpdater.read in cursor_updater.go to see the switch to queries.SelectVectorClock and the updated node-to-sequence mapping.

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📊 Macroscope summarized 4994e4d. 1 file reviewed, 2 issues evaluated, 2 issues filtered, 0 comments posted

🗂️ Filtered Issues

pkg/api/metadata/cursor_updater.go — 0 comments posted, 2 evaluated, 2 filtered

• line 93: Possible nil dereference if cu.store is nil. read() calls queries.New(cu.store).SelectVectorClock(cu.ctx) (line 93). If the *sql.DB passed to NewCursorUpdater was nil, queries.New stores a nil DBTX, and SelectVectorClock will invoke q.db.QueryContext(...) on a nil receiver, which will panic at runtime. There is no guard in NewCursorUpdater or read() to prevent this. Add a nil check on store at construction or before invoking the query and return an error if nil. [ Low confidence ]
• line 100: Behavior/contract parity risk: The diff changes the query used from GetLatestCursor to SelectVectorClock, and the mapped field from row.MaxSequenceID to row.OriginatorSequenceID (line 100). If these two queries/fields are not semantically equivalent (e.g., GetLatestCursor returned a per-node maximum and SelectVectorClock returns something else or has different grouping/ordering), the computed cursor may change, potentially causing missed or extra subscriber notifications or an incorrect cursor state. Verify that SelectVectorClock returns exactly one record per OriginatorNodeID with the correct latest sequence and that OriginatorSequenceID is the intended value. If not, adapt the mapping or query to preserve the previous externally visible behavior. [ Low confidence ]

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