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From Dmitriy Pavlov <dpavlov....@gmail.com>
Subject Re: Pessimistic Mode and Transactions and 2PC
Date Wed, 08 Aug 2018 12:20:43 GMT
Hi John,

Are these questions related to some contribution?

Sincerely,
Dmitriy Pavlov

ср, 8 авг. 2018 г. в 3:18, John Wilson <sami.hailu.15@gmail.com>:

> Hi,
>
> Assume the following:
>
>
>    - I have a transaction coordinator and two primary nodes with 0 backup
>    nodes.
>    - Persistence store is enabled.
>    - I'm running a transaction in pessimistic mode with serializable
>    isolation.
>
> I have these questions:
>
>    1. What exactly happens during the prepare phase? Only acquiring locks
>    on the two primary nodes? Or do the primary nodes themselves, in
> addition
>    to acquiring locks, write to their respective WAL a TxRecord with a
> "begin
>    prepare" info?
>    2. Assume locks have been acquired successfully, would the nodes then
>    write a "prepared" TxRecord to WAL before returning a "Yes" vote to
>    coordinator?
>    3. When the coordinator sends a commit message, would each node write
>    the key-values to the DataRecord and a commit to the TxRecord before
>    returning to coordinator?
>
>
> Overall, I'm trying to understand what happens exactly during prepare and
> commit phases and when the key-values involved in the transaction are
> actually written; as well as the exact updates that are written to the WAL
> files in each phase.
>
> appreciate your response.
>
> Thanks,
>

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