Cross Shard Locking Scheme - (1)

Sharding
22

Let’s say you have a transaction T1 that needs access to two resources, located on two different shards, such that it needs to do the following operations:

  1. LOCK (T1, R[0], S[0])
  2. LOCK (T1, R[1], S[1])

Then let’s say another transaction T2 comes in that wants access to the same resources:

  1. LOCK (T2, R[0], S[0])
  2. LOCK (T2, R[1], S[1])

Then let’s say this is what actually gets executed:

  1. LOCK (T1, R[0], S[0])
  2. LOCK (T2, R[1], S[1])

Now, neither T1 or T2 can proceed, hence deadlock.

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