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Audience syncs fan out array-valued identifier fields into separate records — one per element — so a column holding multiple identifiers (such as several email addresses or mobile advertising IDs) syncs each value individually. It needs no configuration; it happens at sync time whenever a mapped identifier field contains an array. To add identifiers beyond what your source data provides, see Match Booster.
This is distinct from array expansion, which is a separate feature that explodes array columns at the model query level for non-audience sync types. Audience identifier fan-out is automatic and applies only to identifier fields in audience syncs.

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How it works

If your model contains a row with an array-valued identifier field: Hightouch sends three separate records to the destination: Each array element is synced individually so the destination can match on every identifier. Scalar (non-array) values are unaffected and synced as-is.

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Supported destinations

Fan-out works with audience destinations that match on identifiers — the ad platforms, such as Google Ads (Customer Match), Meta (Custom Audiences), and TikTok. Any audience destination that accepts identifier fields supports it. For the current list of destinations and their capabilities, see the integration catalog.

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Requirements

  • An audience sync to a destination that matches on identifiers.
  • The source column must be a true array type, not a JSON string. For example, Snowflake ARRAY, BigQuery ARRAY<STRING>, or Postgres text[] / jsonb arrays all work.
  • A string like '["id1","id2"]' stored as VARCHAR will not be fanned out. If your data is stored this way, use a SQL transformation (e.g., PARSE_JSON() in Snowflake) to convert it to a native array before syncing.
Fan-out increases the number of API requests sent to the destination. If your arrays are large, this may affect sync duration.

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Linked identifier fields

When multiple identifier fields are mapped (for example, first name and last name), Hightouch preserves the association between values at the same array index. For independent fields like email and mobile ID, all combinations are sent to maximize match rates.
  • Match Booster — Enrich your audience data with additional identifiers to improve match rates across audience destinations.
Last modified on August 20, 2026