Tom Lane bedb78d386 Implement sharable row-level locks, and use them for foreign key references ... to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.		2005-04-28 21:47:18 +00:00
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Makefile	$Header: -> $PostgreSQL Changes ...	2003-11-29 19:52:15 +00:00
rewriteDefine.c	Completion of project to use fixed OIDs for all system catalogs and	2005-04-14 20:03:27 +00:00
rewriteHandler.c	Implement sharable row-level locks, and use them for foreign key references	2005-04-28 21:47:18 +00:00
rewriteManip.c	Make the behavior of HAVING without GROUP BY conform to the SQL spec.	2005-03-10 23:21:26 +00:00
rewriteRemove.c	Completion of project to use fixed OIDs for all system catalogs and	2005-04-14 20:03:27 +00:00
rewriteSupport.c	Completion of project to use fixed OIDs for all system catalogs and	2005-04-14 20:03:27 +00:00