further improve log noise

db/helpers.go

@@ -3,6 +3,7 @@ package db
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 	"log/slog"
 	"sort"
@@ -56,7 +57,13 @@ func EnsureColumns(ctx context.Context, dbConn *sqlx.DB, tableName string, colum
 func execLog(ctx context.Context, dbConn *sqlx.DB, query string, args ...interface{}) (sql.Result, error) {
 	res, err := dbConn.ExecContext(ctx, query, args...)
 	if err != nil {
-		slog.Warn("db exec failed", "query", strings.TrimSpace(query), "error", err)
+		q := strings.TrimSpace(query)
+		msg := strings.ToLower(err.Error())
+		if strings.Contains(msg, "duplicate column name") || strings.Contains(msg, "already exists") {
+			slog.Debug("db exec skipped (already exists)", "query", q, "error", err)
+		} else {
+			slog.Warn("db exec failed", "query", q, "error", err)
+		}
 	}
 	return res, err
 }
@@ -86,6 +93,10 @@ func AddColumnIfMissing(ctx context.Context, dbConn *sqlx.DB, tableName string,
 	if _, err := SafeTableName(tableName); err != nil {
 		return err
 	}
+	// Skip ALTER if the column already exists to avoid noisy duplicate errors.
+	if exists, err := ColumnExists(ctx, dbConn, tableName, column.Name); err == nil && exists {
+		return nil
+	}
 	query := fmt.Sprintf(`ALTER TABLE %s ADD COLUMN "%s" %s`, tableName, column.Name, column.Type)
 	if _, err := execLog(ctx, dbConn, query); err != nil {
 		errText := strings.ToLower(err.Error())