Patch to allow vacuum on multi-segment tables, from Hiroshi Inoue

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 5d84956059fa8c4dfb5cbc542da3ebb08c4e2349..b5d7b86c21dc9c4301b9b6fa4d43f43cbbf18f9a 100644 (file)
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.45 1999/06/11 02:39:43 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.46 1999/06/18 16:47:23 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -674,11 +674,12 @@ mdnblocks(Relation reln)
        segno = 0;
        for (;;)
        {
-               if (v->mdfd_lstbcnt == RELSEG_SIZE
-                       || (nblocks = _mdnblocks(v->mdfd_vfd, BLCKSZ)) == RELSEG_SIZE)
+               nblocks = _mdnblocks(v->mdfd_vfd, BLCKSZ);
+               if (nblocks > RELSEG_SIZE)
+                       elog(FATAL, "segment too big in mdnblocks!");
+               v->mdfd_lstbcnt = nblocks;
+               if (nblocks == RELSEG_SIZE)
                {
-
-                       v->mdfd_lstbcnt = RELSEG_SIZE;
                        segno++;
 
                        if (v->mdfd_chain == (MdfdVec *) NULL)
@@ -711,22 +712,55 @@ mdtruncate(Relation reln, int nblocks)
        MdfdVec    *v;
 
 #ifndef LET_OS_MANAGE_FILESIZE
-       int                     curnblk;
+       int                     curnblk,
+                               i,
+                               oldsegno,
+                               newsegno,
+                               lastsegblocks;
+       MdfdVec                 **varray;
 
        curnblk = mdnblocks(reln);
-       if (curnblk / RELSEG_SIZE > 0)
-       {
-               elog(NOTICE, "Can't truncate multi-segments relation %s",
-                       reln->rd_rel->relname.data);
-               return curnblk;
-       }
+       if (nblocks > curnblk)
+               return -1;
+       oldsegno = curnblk / RELSEG_SIZE;
+       newsegno = nblocks / RELSEG_SIZE;
+
 #endif
 
        fd = RelationGetFile(reln);
        v = &Md_fdvec[fd];
 
+#ifndef LET_OS_MANAGE_FILESIZE
+       varray = (MdfdVec **)palloc((oldsegno + 1) * sizeof(MdfdVec *));
+       for (i = 0; i <= oldsegno; i++)
+       {
+               if (!v)
+                       elog(ERROR,"segment isn't open in mdtruncate!");
+               varray[i] = v;
+               v = v->mdfd_chain;
+       }
+       for (i = oldsegno; i > newsegno; i--)
+       {
+               v = varray[i];
+               if (FileTruncate(v->mdfd_vfd, 0) < 0)
+               {
+                       pfree(varray);
+                       return -1;
+               }
+               v->mdfd_lstbcnt = 0;
+       }
+       /* Calculate the # of blocks in the last segment */
+       lastsegblocks = nblocks - (newsegno * RELSEG_SIZE);
+       v = varray[i];
+       pfree(varray);
+       if (FileTruncate(v->mdfd_vfd, lastsegblocks * BLCKSZ) < 0)
+               return -1;
+       v->mdfd_lstbcnt = lastsegblocks;
+#else
        if (FileTruncate(v->mdfd_vfd, nblocks * BLCKSZ) < 0)
                return -1;
+       v->mdfd_lstbcnt = nblocks;
+#endif
 
        return nblocks;