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;