Re: HOT chain validation in verify_heapam() - Mailing list pgsql-hackers

 @@ -504,9 +516,269 @@ verify_heapam(PG_FUNCTION_ARGS)

referring above code, check_tuple(&ctx); do have this check but we populate lp_valid before that call. 

Populating lp_valid before check_tuple() is intentional because even if we do changes to get the return status from check_tuple() to populate that in lp_valid, it will be hard to validate cases that are dependent on aborted transaction (like "tuple with aborted xmin %u was updated to produce a tuple at offset %u with committed xmin %u") because check_tuple_visibility is also looking for aborted xmin and return false if tuple's xmin is aborted, in fact we can add one more parameter to check_tuple and get the status of transaction if it is aborted and accordingly set lp_valid to true but that will add unnecessary complexity and don't find it convincing implementation. Alternatively, I found rechecking xid_status is simpler and straight.

 

ok, I will change it to  InvalidOffsetNumber at all the places, we need ctx.offnum to have the value of the predecessor array as this will be internally used by report_corruption function to generate the message(eg. below), and the format of these message's seems more simple and meaningful to report corruption.

  report_corruption(&ctx,
                                                                  psprintf("heap-only update produced a non-heap only tuple at offset %u",
                                                                                   (unsigned) currentoffnum));

Here we don't need to mention ctx.offnum explicitly in the above message as this will be taken care of by the code below.

"report_corruption_internal(Tuplestorestate *tupstore, TupleDesc tupdesc,
                                                   BlockNumber blkno, OffsetNumber offnum,
                                                   AttrNumber attnum, char *msg)
{
        Datum           values[HEAPCHECK_RELATION_COLS] = {0};
        bool            nulls[HEAPCHECK_RELATION_COLS] = {0};
        HeapTuple       tuple;

        values[0] = Int64GetDatum(blkno);
        values[1] = Int32GetDatum(offnum);"