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Type:
Bug
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: None
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None
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Storage Engines 2019-07-19
While working on WT-4674, I came across this potential bug:
Other than creating a birthmark record in lookaside for the on-disk value, we are also inserting in lookaside the birthmark updates from the update chain. After going through a series of lookaside eviction and re-instantiation, a page will potentially end up with several birthmark records per key. This is unexpected and needs to be investigated and understood if there is a bug here.
Steps to reproduce:
1. Add an assert that we are not inserting a birthmark into lookaside other than for the on-disk value
2. Run test_las02.py to hit the assert.
diff --git a/src/cache/cache_las.c b/src/cache/cache_las.c
index 6b1a82d08..661931b5f 100644
--- a/src/cache/cache_las.c
+++ b/src/cache/cache_las.c
@@ -791,10 +791,12 @@ __wt_las_insert_block(WT_CURSOR *cursor,
upd->start_ts, upd->durable_ts,
upd->prepare_state, WT_UPDATE_BIRTHMARK,
&las_value);
- } else
+ } else {
+ WT_ASSERT(session, upd->type != WT_UPDATE_BIRTHMARK);
cursor->set_value(cursor, upd->txnid,
upd->start_ts, upd->durable_ts,
upd->prepare_state, upd->type, &las_value);
+ }
/*
* Using update looks a little strange because the keys
test_las02.test_las02.test_las: started in WT_TEST/test_las02.test_las02.test_las.0 test_las02.test_las02.test_las (subunit.RemotedTestCase) test_las02.test_las02.test_las ... ERROR ====================================================================== ERROR: test_las02.test_las02.test_las (subunit.RemotedTestCase) test_las02.test_las02.test_las ---------------------------------------------------------------------- _StringException: lost connection during test 'test_las02.test_las02.test_las' ---------------------------------------------------------------------- Ran 1 test in 1.847s FAILED (errors=1) $ cat WT_TEST/test_las02.test_las02.test_las.0/stderr.txt [1562648573:541810][8515:0x7f91577fe700], test_las02.test_las02.test_las, file:las02_main.wt, eviction-server: __wt_las_insert_block, 795: upd->type != WT_UPDATE_BIRTHMARK [1562648573:541876][8515:0x7f91577fe700], test_las02.test_las02.test_las, file:las02_main.wt, eviction-server: __wt_abort, 30: aborting WiredTiger library
- is related to
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- Closed
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