[Progress Communities] [Progress OpenEdge ABL] Forum Post: RE: CDC policies and OM latches

  • Thread starter Thread starter Richard Banville
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Richard Banville

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This is to provide isolation from uncommitted changes to object entries. When making changes to an object the "old" committed version of the object is pinned in the cache while the new uncommitted version resides on disk as it is being changed. This is how we ensure all other OLTP sees only the committed version of the object entry as opposed to the changed but not committed yet version. If the entry was not pinned in the cache, it could be paged out and when read on demand from disk NO-LOCK, the uncommitted version would show up in the cache. After the transaction which changed the cache entry ends, committed or rolled back, the entry in the cache will be updated with the current on-disk version the next time it is referenced.

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