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Database training
4.1.23. Dirty read (or Temporary update)
T
1
read_item(X);
X=X-N;
write_item(X);
<T
1
fails>
<T
1
rollback>
read_item(X);
X=X+N;
write_item(X);
T
2
read_item(X);
X=X+M;
write_item(X);
T
2
reads temporary incorrect value of X
‹ 4.1.22. Lost update
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4.1.24. Incorrect summary ›
s5 slideshow