Re: ERROR: could not read block

"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> Is there anything you would like me to include in my build for my
> test runs, or any steps you would like me to take during the tests?

You might want to insert some debugging elog's into mdread() in md.c,
rather than in its caller smgrread.  I'm concerned that by the time
control comes back to smgrread, the Windows last-error might have
been changed; in any case, we'd not know exactly which of the steps
in mdread failed.  I'd suggest something like

    if (FileSeek(v->mdfd_vfd, seekpos, SEEK_SET) != seekpos)
+    {
+        elog(LOG, "seek failed on relation %u/%u/%u: %d",
+             reln->smgr_rnode.spcNode,
+             reln->smgr_rnode.dbNode,
+             reln->smgr_rnode.relNode,
+             GetLastError());
        return false;
+    }

    status = true;
    if ((nbytes = FileRead(v->mdfd_vfd, buffer, BLCKSZ)) != BLCKSZ)
    {
+        elog(LOG, "read failed on relation %u/%u/%u: %d bytes, %d",
+             reln->smgr_rnode.spcNode,
+             reln->smgr_rnode.dbNode,
+             reln->smgr_rnode.relNode,
+             nbytes,
+             GetLastError());
        /*
         * If we are at or past EOF, return zeroes without complaining. Also
         * substitute zeroes if we found a partial block at EOF.

(untested, but something like this should do it)

            regards, tom lane