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  1. WiredTiger
  2. WT-5185

Base update can't be found when reading a modify in LAS

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
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      Description

      An assertion is firing in test_las07 in the relevant history feature branch where we try to read a modify from the lookaside and are unable to find a standard update to apply it on top of.

      There is an existing bug where the standard update is the on-disk version for that value and won't exist in lookaside (WT-5186) however this is NOT what is happening in this instance. The standard update that we're looking for is not in the update list OR the lookaside so it has probably been lost somehow as part of a bad eviction.

      (lldb) frame select 3
      frame #3: 0x00007ffff57e5c81 libwiredtiger-3.2.2.so`__wt_find_lookaside_upd(session=0x0000555555dcb448, cbt=0x000055555646a310, updp=0x00007fffffffc398, allow_prepare=false) at cache_las.c:1508
         1506	                WT_ASSERT(session, las_btree_id == S2BT(session)->id);
         1507	                WT_ERR(__wt_compare(session, NULL, las_key, key, &cmp));
      -> 1508	                WT_ASSERT(session, cmp == 0);
         1509	                WT_ASSERT(session, __wt_txn_visible(session, _las_txnid, _las_timestamp));
         1510	#endif
         1511	                WT_ERR(cursor->get_value(
      (lldb) frame variable cmp
      (int) cmp = -1
      

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              • Assignee:
                alex.cameron Alex Cameron
                Reporter:
                alex.cameron Alex Cameron
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                Dates

                • Created:
                  Updated:
                  Resolved: