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Type:
Task
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Replication
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Labels:None
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Fully Compatible
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Repl 2019-03-11
The current plan for Prepare Support for Transactions uses an in-memory data structure to maintain the oldest active transaction timestamp. Instead, we can store the first oplog entry's timestamp of a transaction in the transaction table. Thus the transaction table has all necessary information to calculate the oldest active transaction timestamp. With SERVER-39679, this calculation may be done only when a checkpoint is taken or an initial sync starts, so its performance isn't a big concern. The updates on the transaction table are timestamped, so calculating the oldest require timestamp is just a read at the checkpoint's timestamp.
If table scan's performance isn't good enough, we can add an index on the "firstTimestamp" field. The index can be a partial index on "firstTimestamp" when a new "active: true" field exists, so that retryable writes and finished transactions don't affect the performance.
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- is duplicated by
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- Closed
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SERVER-39813 Add the oldest required timestamp into server status
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- Closed
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