Transaction Isolation on select, insert, delete
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by Bradford
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Published on 2010-04-05T21:09:04Z
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2010/04/05
21:13 UTC
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What could possibly go wrong with the following transaction if executed by concurrent users in the default isolation level of READ COMMITTED?
BEGIN TRANSACTION
SELECT * FROM t WHERE pid = 10 and r between 40 and 60
-- ... this returns tid = 1, 3, 5
-- ... process returned data ...
DELETE FROM t WHERE tid in (1, 3, 5)
INSERT INTO t (tid, pid, r) VALUES (77, 10, 35)
INSERT INTO t (tid, pid, r) VALUES (78, 10, 37)
INSERT INTO t (tid, pid, r) VALUES (79, 11, 39)
COMMIT
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