Re: HOT chain validation in verify_heapam()

Hi Himanshu,

Many thanks for working on this!

> Please find attached the patch with the above idea of HOT chain's validation

Please correct me if I'm wrong, but don't we have a race condition here:

```
+            if ((TransactionIdDidAbort(pred_xmin) ||
TransactionIdIsInProgress(pred_xmin))
+                && !TransactionIdEquals(pred_xmin, curr_xmin))
             {
```

The scenario that concerns me is the following:

1. TransactionIdDidAbort(pred_xmin) returns false
2. The transaction aborts
3. TransactionIdIsInProgress(pred_xmin) returns false
4. (false || false) gives us false. An error is reported, although
actually the condition should have been true.

-- 
Best regards,
Aleksander Alekseev