Re: SSI freezing bug

Hi,


On 2013-09-20 13:55:36 +0300, Heikki Linnakangas wrote:
> When a tuple is predicate-locked, the key of the lock is ctid+xmin. However,
> when a tuple is frozen, its xmin is changed to FrozenXid. That effectively
> invalidates any predicate lock on the tuple, as checking for a lock on the
> same tuple later won't find it as the xmin is different.
> 
> Attached is an isolationtester spec to demonstrate this.

Do you have any idea to fix that besides keeping the xmin horizon below the
lowest of the xids that are predicate locked? Which seems nasty to
compute and is probably not trivial to fit into the procarray.c
machinery?

Greetings,

Andres Freund

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