From: Ann W. Harrison
Date: October 15 2008 5:45pm
Subject: Hypothetical on failing to thaw chilled record
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Here's the timeline ...  all transactions on separate connections and
concurrent except as noted.



Assume table t1 (f1 integer) with an index on f1.


T1:  insert into table1 values 3;

T1:  commit;

T2:  start;

T3:  start;

T3:  update t1 set f1 = 5 where f1 = 3;

(at this point the index on f1 has entries for values 3 and 5, both
with record 1. There's a record version object with the new and
old versions in the record cache.  The old index entry has been
processed, and there's a new index entry in T3's deferred index)

System chills T3 changes - new version of record 1 is chilled, old
version is left in memory as back version.

T3:  commit;

T2:  commit;

T4:  select * from table1 where f1 > 1 and f1 < 4; (index bitmap
built, with hit for 3);

System removes obsolete version of record 1 (f1 = 3), from cache
and disk, and index.  Index lookup find a hit for 3 on record 1.

T3 becomes write complete, T4 has a dependency on T3

Thaw fails to find record with that value
Fetch fails to find record with that value