Hi,
+ skip = !ExecLockTableTuple(erm->relation, &tid, markSlot,
+ estate->es_snapshot, estate->es_output_cid,
+ lockmode, erm->waitPolicy, &epq_needed);
+ if (skip)
It seems the variable skip is only used above. The variable is not needed - if statement can directly check the return value.
+ * Locks tuple with given TID with given lockmode following given wait
given appears three times in the above sentence. Maybe the following is bit easier to read:
Locks tuple with the specified TID, lockmode following given wait policy
+ * Checks whether a tuple containing the same unique key as extracted from the
+ * tuple provided in 'slot' exists in 'pk_rel'.
I think 'same' is not needed here since the remaining part of the sentence has adequately identified the key.
+ if (leaf_pk_rel == NULL)
+ goto done;
It would be better to avoid goto by including the cleanup statements in the if block and return.
+ if (index_getnext_slot(scan, ForwardScanDirection, outslot))
+ found = true;
+
+ /* Found tuple, try to lock it in key share mode. */
+ if (found)
Since found is only assigned in one place, the two if statements can be combined into one.
Cheers
