Re: [HACKERS] [PATCH] pageinspect function to decode infomasks

I had a quick look into this patch and also tested it and following
are my observations.

1) I am seeing a server crash when passing any non meaningful value
for t_infomask2 to heap_infomask_flags().

postgres=# SELECT heap_infomask_flags(2816, 3);
server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!> \q

Following is the backtrace,

(gdb) bt
#0  0x0000000000d9c55b in pg_detoast_datum (datum=0x0) at fmgr.c:1833
#1  0x0000000000b87374 in construct_md_array (elems=0x2ad74c0,
nulls=0x0, ndims=1, dims=0x7ffc0b0bbcd0, lbs=0x7ffc0b0bbcc0,
elmtype=25, elmlen=-1,
    elmbyval=0 '\000', elmalign=105 'i') at arrayfuncs.c:3382
#2  0x0000000000b8709f in construct_array (elems=0x2ad74c0, nelems=10,
elmtype=25, elmlen=-1, elmbyval=0 '\000', elmalign=105 'i') at
arrayfuncs.c:3316
#3  0x00007fb8001603a5 in heap_infomask_flags (fcinfo=0x2ad3b88) at
heapfuncs.c:597

2) I can see the documentation for heap_infomask(). But, I do not see
it being defined or used anywhere in the patch.

+     <para>
+      The <function>heap_infomask</function> function can be used to unpack the
+      recognised bits of the infomasks of heap tuples.
+     </para>

3) If show_combined flag is set to it's default value and a tuple is
frozen then may i know the reason for not showing it as frozen tuple
when t_infomask2
is passed as zero.

4) I think, it would be better to use the same argument name for the
newly added function i.e heap_infomask_flags() in both documentation
and sql file. I am basically refering to 'include_combined' argument.
IF you see the function definition, the argument name used is
'include_combined' whereas in documentation you have mentioned
'show_combined'.