Re: Add a filed to PageHeaderData

On Tue, Jun 24, 2014 at 10:18 PM, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>
wrote:

>
> On Tue, Jun 24, 2014 at 3:40 PM, Kevin Grittner <kgrittn(at)ymail(dot)com> wrote:
> >
> > Soroosh Sardari <soroosh(dot)sardari(at)gmail(dot)com> wrote:
> >
> > > I check this problem with a virgin source code of
> > > postgresql-9.3.2. So the bug is not for my codes.
> >
> > > By the way, following code has two different output and it is
> > > weird.
> >
> > I can confirm that I see the difference in 9.3.2, and that I don't
> > see the difference in 9.3.4. Upgrade.
> >
> > http://www.postgresql.org/support/versioning/
> >
> > There's really no point in reporting a possible bug on a version
> > with known bugs which have already had fixes published.
> >
>
> FWIW I can reproduce this on HEAD with the attached patch. I could
> reproduce this on a 64-bit Ubuntu as well as 64-bit Mac OSX. Very confusing
> it is because I tried with various values for N in char[N] array and it
> fails for N=20. Other values I tried are 4, 12, 22, 24 and the test passes
> for all of them. The logic for trying other values is to see if pd_linp[]
> starting on un-aligned boundary can trigger the issue. But there seem to be
> no correlation.
>
> postgres=# select version();
>
> PostgreSQL 9.5devel on x86_64-apple-darwin13.2.0, compiled by Apple LLVM
> version 5.1 (clang-503.0.38) (based on LLVM 3.4svn), 64-bit
>
> postgres=# -- test SP-GiST index that's been built incrementally
>
> postgres=# create table test_range_spgist(ir int4range);
> postgres=# create index test_range_spgist_idx on test_range_spgist using
> spgist (ir);
> postgres=# insert into test_range_spgist select int4range(g, g+10) from
> generate_series(1,586) g;
> INSERT 0 586
>
> postgres=# SET enable_seqscan = t;
> postgres=# SET enable_indexscan = f;
> postgres=# SET enable_bitmapscan = f;
>
> postgres=# select * from test_range_spgist where ir -|- int4range(100,500);
>
> ir
> -----------
> [90,100)
> [500,510)
> (2 rows)
>
> postgres=# SET enable_seqscan = f;
> postgres=# select * from test_range_spgist where ir -|- int4range(100,500);
>
> ir
> -----------
> [90,100)
> [500,510)
> (2 rows)
>
> At this point, both rows are visible via index scan as well as seq scan.
>
> postgres=# insert into test_range_spgist select int4range(g, g+10) from
> generate_series(587,587) g;
> INSERT 0 1
>
> postgres=# select * from test_range_spgist where ir -|- int4range(100,500);
> ir
> ----------
> [90,100)
> (1 row)
>
> Ouch. The second row somehow disappeared.
>
> postgres=# SET enable_seqscan = t;
> postgres=# select * from test_range_spgist where ir -|- int4range(100,500);
>
> ir
> -----------
> [90,100)
> [500,510)
> (2 rows)
>
> So the last INSERT suddenly makes one row disappear via the index scan
> though its still reachable via seq scan. I tried looking at the SP-Gist
> code but clearly I don't understand it a whole lot to figure out the issue,
> if one exists.
>
>
> Thanks,
> Pavan
>
> --
> Pavan Deolasee
> http://www.linkedin.com/in/pavandeolasee
>

Is there any plug in to examine each page of spgist index?
Unfortunately pageinspect only work for btree index.