5.21 Summary of intention locking on a publicrow table
NOTE: the shading on this picture may not be accurate. Please click on
the picture to obtain a larger image, which is accurate.
Key points
- The following locks are obtained by default when a read or a write is made to
a single row of a PUBLICROW table:
- READ:
- An IS lock is obtained on the table.
- An IS lock is obtained on the page.
- An S lock is obtained on the row.
- READ with an intention to write (such as a
REFETCH statement,
or a DECLARE CURSOR FOR UPDATE followed by an OPEN
and a FETCH):
- An IX lock is obtained on the table.
- An IX lock is obtained on the page.
- An SIX lock is obtained on the row (remember that no other transaction can
read or modify a row or page that has been locked with an SIX lock).
- WRITE:
- An IX lock is obtained on the table.
- An IX lock is obtained on the page.
- An X lock is obtained on the row.
Page last updated on November 29, 1995
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