Ok, not sure why my first attempt didn't turn this up. I found the
split in segment 334/91:
rmgr: Btree len (rec/tot): 3776/ 9220, tx: 95765459, lsn:
334/91455AB8, prev 334/91455A70, bkp: 0100, desc: split_l: rel
1663/16385/1665279 left 175193, right 193740, next 182402, level 0,
firstright 138
I've attached all the xlog records pertaining to this relation
grepping for either of these two blocks.
Now interestingly the hot backup was taken starting at 334/90 and
replay didn't finish until 339/65 so it is entirely possible, even
likely, that the backup caught this split in an inconsistent state.
How should I go about dumping the two blocks? I have the backup prior
to WAL replay as well as all the WAL for this time period. I can't
connect to the database so I'm guessing this will look like replay
until it hits a record for these block, use dd to extract the block,
rinse lather repeat. Then dump each of those extracted pages using
pageinspect on byteas. This sounds pretty laborious :(