Hi, While reading source code, I realized that comment of GetOldestXmin mentions;
* if rel = NULL and there are no transactions running in the current * database, GetOldestXmin() returns latestCompletedXid. However, in that case if I understand correctly GetOldestXmin() actually returns latestCompletedXid + 1 as follows; /* * We initialize the MIN() calculation with latestCompletedXid + 1. This * is a lower bound for the XIDs that might appear in the ProcArray later, * and so protects us against overestimating the result due to future * additions. */ result = ShmemVariableCache->latestCompletedXid; Assert(TransactionIdIsNormal(result)); TransactionIdAdvance(result); Attached patch fixes the top comment of GetOldestXmin. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
getoldestxmin_comment.patch
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