Mirroring and CDC(change data capture)

• theyackuza.jr

  SSC Veteran

  Points: 221

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  September 4, 2012 at 12:03 am

  #261333

  I'm using SQLSERVER 2008R2 with HA config using async mirroring. on the principal server, i also activate change data capture (cdc).

  this is the problem, when I pause mirroring, agent cdc could not continue capturing logs for data changes. But when I resume mirroring, automacally agent cdc capture again the change log.

  why this happen?

• Robert Davis

  One Orange Chip

  Points: 28027

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  September 6, 2012 at 12:16 am

  #1534233

  More info please. How are you determining that CDC stops capturing changes?

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• Alex Friedman

  Right there with Babe

  Points: 755

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  July 24, 2017 at 9:06 am

  #1952388

  CDC uses the log reader, same as replication. When mirroring or availability groups are used, by default the log reader will not process log records that have not already been hardened at all mirroring / availability group secondary replicas.

  This can be changed with Trace Flag 1448, which enables the replication log reader to move forward even if the asynchronous secondary replicas have not acknowledged the reception of a change. Even with this trace flag enabled, the log reader always waits for the synchronous secondary replicas.

  References:

  https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/replicate-track-change-data-capture-always-on-availability#CDC

  https://support.microsoft.com/en-us/help/937041/fix-changes-in-the-publisher-database-are-not-replicated-to-the-subscr