Method resolveDatabaseJoins

core/database_join.go:56–137

resolveDatabaseJoins executes queries against target databases for cross-DB relationships.

(
	ctx context.Context,
	from []jsn.Field,
	sfmap map[string]*qcode.Select,
)

// resolveDatabaseJoins executes queries against target databases for cross-DB relationships.
func (s *gstate) resolveDatabaseJoins(
	ctx context.Context,
	from []jsn.Field,
	sfmap map[string]*qcode.Select,
) ([]jsn.Field, error) {
	selects := s.cs.st.qc.Selects

	// Replacement data for the marked insertion points
	to := make([]jsn.Field, len(from))

	var wg sync.WaitGroup
	wg.Add(len(from))

	var cerr error
	var cerrMutex sync.Mutex

	for i, id := range from {
		// Use the json key to find the related Select object
		sel, ok := sfmap[string(id.Key)]
		if !ok {
			return nil, fmt.Errorf("invalid database join field key")
		}
		p := selects[sel.ParentID]

		// Get the target database context
		targetDB := sel.Database
		if targetDB == "" {
			targetDB = sel.Ti.Database
		}

		dbCtx, ok := s.gj.databases[targetDB]
		if !ok {
			return nil, fmt.Errorf("database not found: %s", targetDB)
		}

		// Extract parent ID value. Keep the raw JSON token around so a string
		// primary key like "null" is not confused with a JSON null.
		rawIDVal := bytes.TrimSpace(id.Value)
		idVal := jsn.Value(rawIDVal)

		go func(n int, idVal, rawIDVal []byte, sel *qcode.Select, dbCtx *dbContext, parentTable string) {
			defer wg.Done()

			// Handle null/empty parent IDs gracefully
			if len(idVal) == 0 || bytes.Equal(rawIDVal, []byte("null")) {
				to[n] = jsn.Field{Key: []byte(sel.FieldName), Value: []byte("null")}
				return
			}

			ctx1, span := s.gj.spanStart(ctx, "Execute Database Join")
			if span.IsRecording() {
				span.SetAttributesString(
					StringAttr{"join.database", dbCtx.name},
					StringAttr{"join.table", sel.Table},
					StringAttr{"join.parent_table", parentTable},
				)
			}