Index: src/backend/access/nbtree/nbtree.c
===================================================================
RCS file: /home/pgsql/CvsRoot/pgsql-server/src/backend/access/nbtree/nbtree.c,v
retrieving revision 1.106
diff -c -b -r1.106 nbtree.c
*** src/backend/access/nbtree/nbtree.c	2003/09/29 23:40:26	1.106
--- src/backend/access/nbtree/nbtree.c	2003/11/09 23:39:36
***************
*** 27,32 ****
--- 27,40 ----
  #include "storage/smgr.h"
  
  
+ /*
+  * Variables for vacuum_group_delay option (in commands/vacuumlazy.c)
+  */
+ extern int	vacuum_group_delay_size;	/* vacuum N pages */
+ extern int	vacuum_group_delay_msec;	/* then sleep M msec */
+ extern int	vacuum_group_delay_count;
+ 
+ 
  /* Working state for btbuild and its callback */
  typedef struct
  {
***************
*** 610,615 ****
--- 618,632 ----
  
  			CHECK_FOR_INTERRUPTS();
  
+ 			if (vacuum_group_delay_msec > 0)
+ 			{
+ 				if (++vacuum_group_delay_count >= vacuum_group_delay_size)
+ 				{
+ 					PG_DELAY(vacuum_group_delay_msec);
+ 					vacuum_group_delay_count = 0;
+ 				}
+ 			}
+ 
  			ndeletable = 0;
  			page = BufferGetPage(buf);
  			opaque = (BTPageOpaque) PageGetSpecialPointer(page);
***************
*** 736,741 ****
--- 753,769 ----
  		Buffer		buf;
  		Page		page;
  		BTPageOpaque opaque;
+ 
+ 		CHECK_FOR_INTERRUPTS();
+ 
+ 		if (vacuum_group_delay_msec > 0)
+ 		{
+ 			if (++vacuum_group_delay_count >= vacuum_group_delay_size)
+ 			{
+ 				PG_DELAY(vacuum_group_delay_msec);
+ 				vacuum_group_delay_count = 0;
+ 			}
+ 		}
  
  		buf = _bt_getbuf(rel, blkno, BT_READ);
  		page = BufferGetPage(buf);
Index: src/backend/commands/vacuumlazy.c
===================================================================
RCS file: /home/pgsql/CvsRoot/pgsql-server/src/backend/commands/vacuumlazy.c,v
retrieving revision 1.32
diff -c -b -r1.32 vacuumlazy.c
*** src/backend/commands/vacuumlazy.c	2003/09/25 06:57:59	1.32
--- src/backend/commands/vacuumlazy.c	2003/11/09 23:40:13
***************
*** 88,93 ****
--- 88,100 ----
  static TransactionId OldestXmin;
  static TransactionId FreezeLimit;
  
+ /*
+  * Variables for vacuum_group_delay option (in commands/vacuumlazy.c)
+  */
+ int	vacuum_group_delay_size = 10;	/* vacuum N pages */
+ int	vacuum_group_delay_msec = 0;	/* then sleep M msec */
+ int	vacuum_group_delay_count = 0;
+ 
  
  /* non-export function prototypes */
  static void lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
***************
*** 228,233 ****
--- 235,249 ----
  
  		CHECK_FOR_INTERRUPTS();
  
+ 		if (vacuum_group_delay_msec > 0)
+ 		{
+ 			if (++vacuum_group_delay_count >= vacuum_group_delay_size)
+ 			{
+ 				PG_DELAY(vacuum_group_delay_msec);
+ 				vacuum_group_delay_count = 0;
+ 			}
+ 		}
+ 
  		/*
  		 * If we are close to overrunning the available space for
  		 * dead-tuple TIDs, pause and do a cycle of vacuuming before we
***************
*** 469,474 ****
--- 485,499 ----
  
  		CHECK_FOR_INTERRUPTS();
  
+ 		if (vacuum_group_delay_msec > 0)
+ 		{
+ 			if (++vacuum_group_delay_count >= vacuum_group_delay_size)
+ 			{
+ 				PG_DELAY(vacuum_group_delay_msec);
+ 				vacuum_group_delay_count = 0;
+ 			}
+ 		}
+ 
  		tblk = ItemPointerGetBlockNumber(&vacrelstats->dead_tuples[tupindex]);
  		buf = ReadBuffer(onerel, tblk);
  		LockBufferForCleanup(buf);
***************
*** 799,804 ****
--- 824,838 ----
  					hastup;
  
  		CHECK_FOR_INTERRUPTS();
+ 
+ 		if (vacuum_group_delay_msec > 0)
+ 		{
+ 			if (++vacuum_group_delay_count >= vacuum_group_delay_size)
+ 			{
+ 				PG_DELAY(vacuum_group_delay_msec);
+ 				vacuum_group_delay_count = 0;
+ 			}
+ 		}
  
  		blkno--;
  
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /home/pgsql/CvsRoot/pgsql-server/src/backend/utils/misc/guc.c,v
retrieving revision 1.164.2.1
diff -c -b -r1.164.2.1 guc.c
*** src/backend/utils/misc/guc.c	2003/11/07 21:27:50	1.164.2.1
--- src/backend/utils/misc/guc.c	2003/11/09 23:27:49
***************
*** 73,78 ****
--- 73,80 ----
  extern int	CommitDelay;
  extern int	CommitSiblings;
  extern char *preload_libraries_string;
+ extern int	vacuum_group_delay_size;
+ extern int	vacuum_group_delay_msec;
  
  #ifdef HAVE_SYSLOG
  extern char *Syslog_facility;
***************
*** 1188,1193 ****
--- 1190,1213 ----
  		},
  		&log_min_duration_statement,
  		-1, -1, INT_MAX / 1000, NULL, NULL
+ 	},
+ 
+ 	{
+ 		{"vacuum_group_delay_msec", PGC_USERSET, RESOURCES,
+ 			gettext_noop("Sets VACUUM's delay in milliseconds between processing groups of pages."),
+ 			NULL
+ 		},
+ 		&vacuum_group_delay_msec,
+ 		0, 0, 1000, NULL, NULL
+ 	},
+ 
+ 	{
+ 		{"vacuum_group_delay_size", PGC_USERSET, RESOURCES,
+ 			gettext_noop("Sets VACUUM's group size for the vacuum_group_delay_msec option."),
+ 			NULL
+ 		},
+ 		&vacuum_group_delay_size,
+ 		10, 1, 1000, NULL, NULL
  	},
  
  	/* End-of-list marker */
Index: src/backend/utils/misc/postgresql.conf.sample
===================================================================
RCS file: /home/pgsql/CvsRoot/pgsql-server/src/backend/utils/misc/postgresql.conf.sample,v
retrieving revision 1.92
diff -c -b -r1.92 postgresql.conf.sample
*** src/backend/utils/misc/postgresql.conf.sample	2003/10/08 03:49:38	1.92
--- src/backend/utils/misc/postgresql.conf.sample	2003/11/09 23:04:21
***************
*** 69,74 ****
--- 69,79 ----
  #max_files_per_process = 1000	# min 25
  #preload_libraries = ''
  
+ # - Vacuum napping -
+ 
+ #vacuum_group_delay_size = 10	# range 1-1000 pages ; vacuum this many pages
+ #vacuum_group_delay_msec = 0	# range 0-1000 msec  ; then nap this long
+ 
  
  #---------------------------------------------------------------------------
  # WRITE AHEAD LOG
Index: src/include/miscadmin.h
===================================================================
RCS file: /home/pgsql/CvsRoot/pgsql-server/src/include/miscadmin.h,v
retrieving revision 1.134
diff -c -b -r1.134 miscadmin.h
*** src/include/miscadmin.h	2003/09/24 18:54:01	1.134
--- src/include/miscadmin.h	2003/11/09 23:02:03
***************
*** 96,101 ****
--- 96,111 ----
  		CritSectionCount--; \
  	} while(0)
  
+ /*
+  * Macro using select(2) to nap for milliseconds
+  */
+ #define PG_DELAY(_msec) \
+ { \
+     struct timeval _delay; \
+ 	_delay.tv_sec  = (_msec) / 1000; \
+ 	_delay.tv_usec = ((_msec) % 1000) * 1000; \
+ 	(void) select(0, NULL, NULL, NULL, &_delay);\
+ }
  
  /*****************************************************************************
   *	  globals.h --															 *