Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Tom Lane
Andres Freund writes: > On 2018-01-02 20:40:50 -0500, Tom Lane wrote: >> OK, then there's not a live bug, but I'm a bit tempted to get rid of >> the data[] member anyway. It's not clear to me now that keeping it >> results in net cleaner code. Thoughts? > I like that plan. I don't think the dat

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Andres Freund
On 2018-01-02 20:40:50 -0500, Tom Lane wrote: > Andres Freund writes: > > On 2018-01-03 14:29:15 +1300, Thomas Munro wrote: > >> On Wed, Jan 3, 2018 at 2:20 PM, Tom Lane wrote: > >>> Andres Freund writes: > >>> But note that dsa_pointer can be wider than a regular pointer on > >>> platforms with

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Tom Lane
Andres Freund writes: > On 2018-01-03 14:29:15 +1300, Thomas Munro wrote: >> On Wed, Jan 3, 2018 at 2:20 PM, Tom Lane wrote: >>> Andres Freund writes: >>> But note that dsa_pointer can be wider than a regular pointer on >>> platforms without atomics support. >>> Hm. I did not get that impressi

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Andres Freund
On 2018-01-03 14:29:15 +1300, Thomas Munro wrote: > On Wed, Jan 3, 2018 at 2:20 PM, Tom Lane wrote: > > Andres Freund writes: > >> But note that dsa_pointer can be wider than a regular pointer on > >> platforms without atomics support. > > > > Hm. I did not get that impression from the comments

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Thomas Munro
On Wed, Jan 3, 2018 at 2:20 PM, Tom Lane wrote: > Andres Freund writes: >> But note that dsa_pointer can be wider than a regular pointer on >> platforms without atomics support. > > Hm. I did not get that impression from the comments in dsa.h, > but if it's true then this approach won't work ---

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Tom Lane
Andres Freund writes: > On 2018-01-02 19:08:49 -0500, Tom Lane wrote: >> Now, the existing definition of the struct seems safe on all >> architectures we support, but it would not take much to break it. >> I think we ought to do what we did recently in the memory-context >> code: insert an explici

Re: Ensuring hash tuples are properly maxaligned

2018-01-02 Thread Andres Freund
Hi, On 2018-01-02 19:08:49 -0500, Tom Lane wrote: > Now, the existing definition of the struct seems safe on all > architectures we support, but it would not take much to break it. > I think we ought to do what we did recently in the memory-context > code: insert an explicit padding calculation an