I'm continuously studying Postgres codebase. Hopefully I'll be able to make
some contributions in the future.

For now I'm intrigued about the extensive use of memory alignment. I'm sure
there's some legacy and some architecture that requires it reasoning behind

That aside, since it wastes space (a lot of space in some cases) there must
be a tipping point somewhere. I'm sure one can prove aligned access is
faster in a micro-benchmark but I'm not sure it's the case in a DBMS like
postgres, specially in the page/rows area.

Just for the sake of comparison Mysql COMPACT storage (default and
recommended since 5.5) doesn't align data at all. Mysql NDB uses a fixed
4-byte alignment. Not sure about Oracle and others.

Is it worth the extra space in newer architectures (specially Intel)?
Do you guys think this is something worth looking at?

I'm trying to messing with the *ALIGN macros but so far I wasn't able to
get any conclusive results. My guess is that I'm missing something in the
code or pg_bench doesn't stress the difference enough.

Arthur Silva

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