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What Is a Slot?


A slot is a narrow notch or groove, such as a keyway in a machine or a hole for a coin in a vending machine. The term also refers to a time period in a schedule or scheme, such as the first episode of a show that occupies a peak evening viewing slot. You can book a time slot a week or more in advance.

Some people believe that being able to tell when a slot machine is “ready to pay” is a skill that can be learned. In reality, however, it’s all about luck. A slot’s probability of paying out is determined by the random number generator that runs through thousands of numbers every second. If the computer finds a sequence that corresponds to a reel location, it causes the reels to stop there. The symbols on the stopped reels then determine if the spin was a winner or not.

In BigQuery, slots are purchased and assigned to jobs in pools called reservations. You can create multiple reservations to separate different types of workloads and prevent them from competing for resources. When a query’s capacity demands change, BigQuery automatically re-evaluates the availability of its slots in the reservation and re-allocates them as necessary. If you purchase a slot commitment, the capacity is guaranteed for the length of the commitment period, which can be up to three years or one year. If you do not purchase a slot commitment, your usage is billed monthly for the duration of your plan.