> + /* HOT chains should not intersect. */ > + if (predecessor[nextoffnum] != InvalidOffsetNumber) > + { > + report_corruption(&ctx, > + psprintf("redirect line pointer > points to offset %u, but offset %u also points there", > + (unsigned) nextoffnum, > (unsigned) predecessor[nextoffnum])); > + continue; > + } > ``` > > This type of corruption doesn't seem to be test-covered.
Himanshu, would you be able to try to write a test case for this? I think you need something like this: update a tuple with a lower TID to produce a tuple with a higher TID, e.g. (0,10) is updated to produce (0,11). But then have a redirect line pointer that also points to the result of the update, in this case (0,11).
Sure Robert, I will work on this.
> ``` > + /* > + * If the next line pointer is a redirect, or if it's a tuple > + * but the XMAX of this tuple doesn't match the XMIN of the next > + * tuple, then the two aren't part of the same update chain and > + * there is nothing more to do. > + */ > + if (ItemIdIsRedirected(next_lp)) > + continue; > ``` > > lcov shows that the `continue` path is never executed. This is > probably not a big deal however.
It might be good to have a negative test case for this, though. Let's say we, e.g. update (0,1) to produce (0,2), but then abort. The page is HOT-pruned. Then we add insert a new tuple at (0,2), HOT-update it to produce (0,3), and commit. Then we HOT-prune again. Possibly we could try to write a test case that verifies that this does NOT produce any corruption indication.
will work on this too.
> ``` > +$node->append_conf('postgresql.conf','max_prepared_transactions=100'); > ``` > > From what I can tell this line is not needed.
That surprises me, because the new test cases involve preparing a transaction, and by default max_prepared_transactions=0. So it seems to me (without testing) that this ought to be required. Did you test that it works without this setting?
The value of 100 seems a bit excessive, though. Most TAP tests seem to use 10.
We need this for prepare transaction, will change it to 10.
