Re: [PATCH] Redudant initilization

Em dom., 29 de mar. de 2020 às 21:57, Kyotaro Horiguchi <
horikyota(dot)ntt(at)gmail(dot)com> escreveu:

> Hello.
>
> At Sat, 28 Mar 2020 19:04:00 -0300, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
> wrote in
> > Hi,
> > This patch fixes some redundant initilization, that are safe to remove.
>
> > diff --git a/src/backend/access/gist/gistxlog.c
> b/src/backend/access/gist/gistxlog.c
> > index d3f3a7b803..ffaa2b1ab4 100644
> > --- a/src/backend/access/gist/gistxlog.c
> > +++ b/src/backend/access/gist/gistxlog.c
> > @@ -396,7 +396,7 @@ gistRedoPageReuse(XLogReaderState *record)
> > if (InHotStandby)
> > {
> > FullTransactionId latestRemovedFullXid =
> xlrec->latestRemovedFullXid;
> > - FullTransactionId nextFullXid =
> ReadNextFullTransactionId();
> > + FullTransactionId nextFullXid;
>
> I'd prefer to preserve this and remove the latter.
>

Ok.

> > diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
> > index 9d9e915979..795cf349eb 100644
> > --- a/src/backend/catalog/heap.c
> > +++ b/src/backend/catalog/heap.c
> > @@ -3396,7 +3396,7 @@ List *
> > heap_truncate_find_FKs(List *relationIds)
> > {
> > List *result = NIL;
> > - List *oids = list_copy(relationIds);
> > + List *oids;
>
> This was just a waste of memory, the fix looks fine.
>
> > diff --git a/src/backend/storage/smgr/md.c
> b/src/backend/storage/smgr/md.c
> > index c5b771c531..37fbeef841 100644
> > --- a/src/backend/storage/smgr/md.c
> > +++ b/src/backend/storage/smgr/md.c
> > @@ -730,9 +730,11 @@ mdwrite(SMgrRelation reln, ForkNumber forknum,
> BlockNumber blocknum,
> > BlockNumber
> > mdnblocks(SMgrRelation reln, ForkNumber forknum)
> > {
> > - MdfdVec *v = mdopenfork(reln, forknum, EXTENSION_FAIL);
> > + MdfdVec *v;
> > BlockNumber nblocks;
> > - BlockNumber segno = 0;
> > + BlockNumber segno;
> > +
> > + mdopenfork(reln, forknum, EXTENSION_FAIL);
> >
> > /* mdopen has opened the first segment */
> > Assert(reln->md_num_open_segs[forknum] > 0);
>
> It doesn't seems *to me* an issue.
>

Not a big deal, but the assignment of the variable v here is a small waste,
since it is again highlighted right after.

> > diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
> > index 8bb00abb6b..7a6a2ecbe9 100644
> > --- a/src/backend/utils/adt/json.c
> > +++ b/src/backend/utils/adt/json.c
> > @@ -990,7 +990,7 @@ catenate_stringinfo_string(StringInfo buffer, const
> char *addon)
> > Datum
> > json_build_object(PG_FUNCTION_ARGS)
> > {
> > - int nargs = PG_NARGS();
> > + int nargs;
>
> This part looks fine.
>
> > int i;
> > const char *sep = "";
> > StringInfo result;
> > @@ -998,6 +998,8 @@ json_build_object(PG_FUNCTION_ARGS)
> > bool *nulls;
> > Oid *types;
> >
> > + PG_NARGS();
> > +
> > /* fetch argument values to build the object */
> > nargs = extract_variadic_args(fcinfo, 0, false, &args, &types,
> &nulls);
>
> PG_NARGS() doesn't have a side-effect so no need to call independently.
>
Sorry, does that mean we can remove it completely?

>
> > diff --git a/src/backend/utils/mmgr/mcxt.c
> b/src/backend/utils/mmgr/mcxt.c
> > index 9e24fec72d..fb0e833b2d 100644
> > --- a/src/backend/utils/mmgr/mcxt.c
> > +++ b/src/backend/utils/mmgr/mcxt.c
> > @@ -475,7 +475,7 @@ MemoryContextMemAllocated(MemoryContext context,
> bool recurse)
> >
> > if (recurse)
> > {
> > - MemoryContext child = context->firstchild;
> > + MemoryContext child;
> >
> > for (child = context->firstchild;
> > child != NULL;
>
> This looks fine.
>

Thank you for the review and consideration.

best regards,
Ranier Vilela