RE: In-placre persistance change of a relation

Hi Horiguchi-san,


Thank you for making a patch so quickly.  I've started looking at it.

What makes you think this is a PoC?  Documentation and test cases?  If there's something you think that doesn't work or
areconcerned about, can you share it? 

Do you know the reason why data copy was done before?  And, it may be odd for me to ask this, but I think I saw someone
referredto the past discussion that eliminating data copy is difficult due to some processing at commit.  I can't find
it.



(1)
@@ -168,6 +168,8 @@ extern PGDLLIMPORT int32 *LocalRefCount;
  */
 #define BufferGetPage(buffer) ((Page)BufferGetBlock(buffer))

+struct SmgrRelationData;

This declaration is already in the file:

/* forward declared, to avoid having to expose buf_internals.h here */
struct WritebackContext;

/* forward declared, to avoid including smgr.h here */
struct SMgrRelationData;


Regards
Takayuki Tsunakawa