Re: New gist vacuum.

On Thu, Sep 10, 2015 at 3:52 PM, Костя Кузнецов <chapaev28@ya.ru> wrote:
> Hello. I am student from gsoc programm.
> My project is sequantial access in vacuum of gist.
>
> New vacuum has 2 big step:
> physical order scan pages and cleaning after 1 step.
>
>
> 1 scan - scan all pages and create information map(hashmap) and add
> information to rescan stack( stack of pages that needed to rescanning

This is interesting work.  I think the patch needs a rebase to the git
HEAD.  There is a minor conflict in gistRedoPageUpdateRecord.  It is a
little confusing  because your patch introduces new code and then
immediately comments it out (using //, which is not a comment style
allowed in our style guide) and that phantom code confuses the
conflict resolution process.

There are several other places throughout the patch that use //
comment style to comment out code which the patch itself added.  Those
should be removed, and the real comments should be converted to /*
this */ style.

I also got a compiler warning, it looks like a missing #include:

gistutil.c: In function 'gistNewBuffer':
gistutil.c:788:4: warning: implicit declaration of function
'TransactionIdPrecedes' [-Wimplicit-function-declaration]
    if (GistPageIsDeleted(page) &&
TransactionIdPrecedes(p->pd_prune_xid, RecentGlobalDataXmin)) {
    ^


Also, I didn't see a check on the size of the stack.  Is there an
argument that this stack will not be able to grow to be large enough
to cause trouble?

Thanks,

Jeff