Thread: small improvement in buffread common

I attach patch which removes useless page header check when page is zeroed. It
is primary used by hash index.

    Zdenek

--
Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql

*** pgsql_page_api.7c9eff0cf439/src/backend/storage/buffer/bufmgr.c    út srp  5 12:31:44 2008
--- pgsql_page_api/src/backend/storage/buffer/bufmgr.c    út srp  5 12:25:01 2008
***************
*** 352,379 ****
          if (zeroPage)
              MemSet((char *) bufBlock, 0, BLCKSZ);
          else
-             smgrread(smgr, blockNum, (char *) bufBlock);
-         /* check for garbage data */
-         if (!PageHeaderIsValid((PageHeader) bufBlock))
          {
!             if (zero_damaged_pages)
              {
!                 ereport(WARNING,
!                         (errcode(ERRCODE_DATA_CORRUPTED),
!                          errmsg("invalid page header in block %u of relation %u/%u/%u; zeroing out page",
!                                 blockNum,
!                                 smgr->smgr_rnode.spcNode,
!                                 smgr->smgr_rnode.dbNode,
!                                 smgr->smgr_rnode.relNode)));
!                 MemSet((char *) bufBlock, 0, BLCKSZ);
              }
-             else
-                 ereport(ERROR,
-                         (errcode(ERRCODE_DATA_CORRUPTED),
-                  errmsg("invalid page header in block %u of relation %u/%u/%u",
-                         blockNum, smgr->smgr_rnode.spcNode,
-                         smgr->smgr_rnode.dbNode,
-                         smgr->smgr_rnode.relNode)));
          }
      }

--- 352,382 ----
          if (zeroPage)
              MemSet((char *) bufBlock, 0, BLCKSZ);
          else
          {
!             smgrread(smgr, blockNum, (char *) bufBlock);
!
!             /* check for garbage data */
!             if (!PageHeaderIsValid((Page) bufBlock))
              {
!                 if (zero_damaged_pages)
!                 {
!                     ereport(WARNING,
!                             (errcode(ERRCODE_DATA_CORRUPTED),
!                              errmsg("invalid page header in block %u of relation %u/%u/%u; zeroing out page",
!                                     blockNum,
!                                     smgr->smgr_rnode.spcNode,
!                                     smgr->smgr_rnode.dbNode,
!                                     smgr->smgr_rnode.relNode)));
!                     MemSet((char *) bufBlock, 0, BLCKSZ);
!                 }
!                 else
!                     ereport(ERROR,
!                             (errcode(ERRCODE_DATA_CORRUPTED),
!                      errmsg("invalid page header in block %u of relation %u/%u/%u",
!                             blockNum, smgr->smgr_rnode.spcNode,
!                             smgr->smgr_rnode.dbNode,
!                             smgr->smgr_rnode.relNode)));
              }
          }
      }

Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
> I attach patch which removes useless page header check when page is zeroed. It 
> is primary used by hash index.

Looks reasonable; applied.
        regards, tom lane