AAID, ECID, AACUSTOMID and the Analytics source connector

Adobe Analytics data contains multiple identity fields. Three important identity fields are given special treatment by the Analytics source connector: AAID, ECID, AACUSTOMID.


Adobe Analytics ID (AAID) is the primary device identifier in Adobe Analytics and is guaranteed to exist on every event passed through the Analytics source connector. AAID is sometimes referred to as the “Legacy Analytics ID” or s_vi cookie id. However, an AAID is created even if the s_vi cookie is not present. AAID is represented by the post_visid_high/post_visid_low columns in Adobe Analytics data feeds.

In the Analytics source connector, AAID is transformed to HEX(post_visid_high) + "-" + HEX(post_visid_low). The AAID field on a given event contains a single identity which may be one of several different types as described in Order of Operations for Analytics IDs. (Within an entire report suite, AAID may contain a mix of types across events. The type for each event is indicated in the post_visid_type column in Analytics data feeds.) See also: Data column reference.


ECID (Experience Cloud ID), also sometimes referred to as MCID (Marketing Cloud ID), is a separate device identifier field which is populated in Adobe Analytics when Analytics is implemented using the Experience Cloud Identity Service. ECID is represented by the mcvisid column in Adobe Analytics data feeds.

If an ECID exists on an event, AAID may be based on ECID depending on whether the Analytics grace period is configured. See also: Analytics and Experience Cloud ID Requests.


AACUSTOMID is a separate identifier field which is populated in Adobe Analytics based on use of the s.VisitorID variable in the Analytics implementation. AACUSTOMID is represented by the cust_visid column in Adobe Analytics data feeds. If AACUSTOMID is present, AAID will be based on AACUSTOMID. (AACUSTOMID trumps all other identifiers as defined by the order of operations mentioned above.)

How the Analytics source connector treats these identities

The Analytics source connector passes these identities through to Adobe Experience Platform in XDM form as:

  • endUserIDs._experience.aaid.id
  • endUserIDs._experience.mcid.id
  • endUserIDs._experience.aacustomid.id

These fields are not marked as identities. Rather, the same identities are copied into XDM’s identityMap as key value pairs as follows:

  • { "key": "AAID", "value": [ { "id": "<identity>", "primary": <true or false> } ] }
  • { "key": "ECID", "value": [ { "id": "<identity>", "primary": <true or false> } ] }
  • { "key": "AACUSTOMID", "value": [ { "id": "<identity>", "primary": false } ] }

The items in <> brackets represent places where actual values would appear.

Within identityMap:

  • If ECID is present it is marked as the primary identity for the event. Note that in this case AAID may be based on ECID per the discussion above.
    Otherwise, AAID is marked as the primary identity for the event.
  • AACUSTOMID is never marked as the Primary ID for the event. However, if AACUSTOMID is present, then AAID is based on AACUSTOMID as per the discussion above.

Customer Journey Analytics and Primary ID

As far as Customer Journey Analytics is concerned, the definition of Primary ID is only important if you decide to use the Primary ID as the Person ID. Doing so is not mandatory, however. You may choose some other identity column as the Person ID.