CREATE TABLE table_3147 ("Result" TEXT, "Date" TEXT, "Race" TEXT, "Venue" TEXT, "Group" TEXT, "Distance" TEXT, "Weight  ( kg ) " TEXT, "Jockey" TEXT, "Winner/2nd" TEXT)

The MacKinnon Stakes races took place on how many venues?
SELECT COUNT("Venue") FROM table_3147 WHERE "Race" = 'Mackinnon Stakes'
SELECT COUNT("Venue") FROM "table_3147" WHERE "Race" = 'Mackinnon Stakes'