What Is a Slot?

A slit or narrow opening, especially one used to receive coins.

The first electromechanical slot machine was developed in the early sixties by Bally. It used a reel with multiple symbols and offered a larger payout than earlier mechanical machines. The game’s popularity was such that many saloons and dance halls began to close to make room for these new machines.

A slot is a placeholder that either waits for content or calls out to get it. Slots work with scenarios to deliver content to the page, and with renderers to determine how that content is presented.

When a query has the right to a slot, it will get the next available time to complete the job when the slot is empty. BigQuery will dynamically balance the slots of all running queries, including any reservations that you have created. For example, you can create a reservation named prod for production workloads and another reservation named test for testing workloads so that they do not compete with each other for resources.

A slot in a schedule or program is an open time that can be filled by someone. The scheduler will usually allocate slots on a rolling basis, so that people who want to come in at later times can do so. For example, someone wanting to attend a lecture may book a ticket a week or more in advance. Similarly, someone might reserve a spot in a training course that is filling up fast.