On 2015/09/02 14:28, Amit Langote wrote:
On 2015-09-02 PM 01:28, Amit Kapila wrote:
On Tue, Sep 1, 2015 at 9:48 PM, Robert Haas <robertmh...@gmail.com> wrote:
I'm not averse to making the "connect to the remote nodes" part of
this solution use something other than the FDW infrastructure at some
point in time if somebody's prepared to build something better. On
the other hand, I think it's extremely clear that the FDW
infrastructure has a large amount of potential upon which we have
thoroughly failed to capitalize. Patches have already been written
for UPDATE/DELETE pushdown and for join pushdown.
Will pushing down writes (Update/Delete) sufficient to maintain sane locking
behaviour and deadlock detection that can occur during writes on multiple
shards? For example it could easily be the case where a single Update
statement could effect multiple shards and cause deadlock due to waits
across the nodes. Now unless we have some distributed lock manager or
some other way to know the information of locks that happens across
shards, it could be difficult to detect deadlocks.
I wonder if Ashutosh's atomic foreign transactions patch would address any
issues inherent in such cases...
The UPDATE/DELETE pushdown, which I've proposed, would ensure the sane
behaviour for inherited UPDATEs/DELETEs, as existing non-pushed-down
UPDATE/DELETE does, because inheritance_planner guarantees that all
backends lock inheritance children in the same order to avoid needless
deadlocks.
Best regards,
Etsuro Fujita
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