On 09/26/2014 03:40 PM, Andres Freund wrote:
On 2014-09-26 15:32:35 +0300, Heikki Linnakangas wrote:
On 09/26/2014 03:30 PM, Andres Freund wrote:
On 2014-09-26 15:24:21 +0300, Heikki Linnakangas wrote:
I don't know what you mean by "in the head of AM", but IMO it would be far
better if we can implement this outside the index AMs. Then it will work
with any index AM.
Also, it's the only chance to make this ever work across partitions.
How so? Assuming there's no overlap in the partitions, you could lock the
page in the index of the partition you're inserting to, just like you would
insert the promise tuple to the right partition.
Well, the 'no overlap' case is boring.
Ok.
At least if you mean that each partition has disctinct value ranges
in the index?
Right.
And the reason that the buffer locking approach in the overlapping case
is that you'd need to hold a large number of pages locked at the same
time. Right?
Yeah, you would. To be honest, I didn't even think about the overlapping
case, I just assumed that the overlapping case is the typical one and
only thought about that.
But primarily I mean that bulk of the uniqueness checking logic has to
live outside the individual AMs. It doesn't sound enticing to reach from
inside one AM into another partitions index to do stuff.
Yeah, that's a non-starter. Even with the index locking stuff, though,
it wouldn't be the AM's responsibility to reach out to other partitions.
- Heikki
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