postgres

History

Kevin Grittner cdf91edba9 Fix serializable mode with index-only scans. Serializable Snapshot Isolation used for serializable transactions depends on acquiring SIRead locks on all heap relation tuples which are used to generate the query result, so that a later delete or update of any of the tuples can flag a read-write conflict between transactions. This is normally handled in heapam.c, with tuple level locking. Since an index-only scan avoids heap access in many cases, building the result from the index tuple, the necessary predicate locks were not being acquired for all tuples in an index-only scan. To prevent problems with tuple IDs which are vacuumed and re-used while the transaction still matters, the xmin of the tuple is part of the tag for the tuple lock. Since xmin is not available to the index-only scan for result rows generated from the index tuples, it is not possible to acquire a tuple-level predicate lock in such cases, in spite of having the tid. If we went to the heap to get the xmin value, it would no longer be an index-only scan. Rather than prohibit index-only scans under serializable transaction isolation, we acquire an SIRead lock on the page containing the tuple, when it was not necessary to visit the heap for other reasons. Backpatch to 9.2. Kevin Grittner and Tom Lane		14 years ago
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examples	Update copyright notices for year 2012.	14 years ago
isolation	Fix serializable mode with index-only scans.	14 years ago
locale	Run newly-configured perltidy script on Perl files.	14 years ago
mb	Lots of doc corrections.	14 years ago
performance	Run newly-configured perltidy script on Perl files.	14 years ago
regress	Drop cheap-startup-cost paths during add_path() if we don't need them.	14 years ago
thread	Run pgindent on 9.2 source tree in preparation for first 9.3	14 years ago
Makefile	Add isolation test to check-world and installcheck-world	14 years ago