Query multiple indices or clusters with {{esql}}

{{esql}} allows you to query across multiple indices, clusters, and projects, and combine data from multiple sources. Learn more in the following sections:

• Query multiple indices
• Query across clusters
• Query across {{serverless-short}} projects {applies_to}serverless: preview
• Combine result sets with subqueries {applies_to}stack: preview 9.4.0 {applies_to}serverless: preview
• Define virtual indices using ES|QL views {applies_to}stack: preview 9.4.0 {applies_to}serverless: unavailable

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