snapshot of https://github.com/seaweedfs/seaweedfs.git (master, 2026-09-16; blobs > 131072B omitted)

weed/filer/postgres/postgres_collation.go

@@ -0,0 +1,69 @@
+package postgres
+
+import (
+	"database/sql"
+	"strings"
+
+	"github.com/seaweedfs/seaweedfs/weed/filer/abstract_sql"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+)
+
+// ConfigureListOrdering switches the list queries to COLLATE "C" when the live
+// filemeta.name collation is locale-aware, so S3 ListObjectsV2 stays
+// lexicographic. The fallback costs a sort, so warn the operator to fix it.
+func ConfigureListOrdering(db *sql.DB, gen *SqlGenPostgres) {
+	if isCockroachDB(db) {
+		// CockroachDB string comparison is already byte-ordered, so the
+		// fallback is redundant; older versions also reject COLLATE "C".
+		return
+	}
+	collation, isBinary, err := nameColumnCollation(db)
+	if err != nil {
+		glog.V(1).Infof("postgres: skip filemeta.name collation check: %v", err)
+		return
+	}
+	if isBinary {
+		return
+	}
+	gen.ForceBinaryCollation = true
+	glog.Warningf(`postgres: filemeta.name collation %q is not byte-ordered, so S3 list order is not byte-lexicographic and clients that merge sorted listings may report spurious diffs. Falling back to a slower COLLATE "C" sort; declare the name column COLLATE "C" (or use a C/C.UTF-8 database collation) for correct, indexed ordering.`, collation)
+}
+
+// isCockroachDB reports whether db is a CockroachDB backend, whose version()
+// string carries "CockroachDB". On any error we assume real Postgres.
+func isCockroachDB(db *sql.DB) bool {
+	var version string
+	if err := db.QueryRow("SELECT version()").Scan(&version); err != nil {
+		glog.V(1).Infof("postgres: skip CockroachDB detection: %v", err)
+		return false
+	}
+	return strings.Contains(version, "CockroachDB")
+}
+
+func nameColumnCollation(db *sql.DB) (collation string, isBinary bool, err error) {
+	// information_schema reports NULL for a column on the database default, so
+	// fall back to datcollate for the effective ordering.
+	row := db.QueryRow(`SELECT
+		(SELECT collation_name FROM information_schema.columns
+			WHERE table_schema = current_schema() AND table_name = $1 AND column_name = 'name'),
+		(SELECT datcollate FROM pg_database WHERE datname = current_database())`, abstract_sql.DEFAULT_TABLE)
+	var columnCollation, dbCollate sql.NullString
+	if err = row.Scan(&columnCollation, &dbCollate); err != nil {
+		return "", false, err
+	}
+	effective := columnCollation.String
+	if !columnCollation.Valid || effective == "" {
+		effective = dbCollate.String
+	}
+	return effective, isByteOrderedCollation(effective), nil
+}
+
+// isByteOrderedCollation reports whether a Postgres locale sorts by byte value
+// (C, POSIX, C.UTF-8) rather than locale order (en_US.UTF-8, ICU, ...).
+func isByteOrderedCollation(name string) bool {
+	switch strings.ToLower(strings.TrimSpace(name)) {
+	case "c", "posix", "c.utf-8", "c.utf8":
+		return true
+	}
+	return false
+}