patch for large queries

Started by Massimo Dal Zottoover 26 years ago4 messages
#1Massimo Dal Zotto
dz@cs.unitn.it

Hi Hackers,

I don't like last minute patches before the final freeze, but I believe that
this one could be useful for people experiencing out-of-memory crashes while
executing queries which retrieve or use a very large number of tuples.

The problem happens when storage is allocated for functions results used in
a large query, for example:

select upper(name) from big_table;
select big_table.array[1] from big_table;
select count(upper(name)) from big_table;

This patch is a dirty hack that fixes the out-of-memory problem for the most
common cases, like the above ones. It is not the final solution for the
problem but it can work for some people, so I'm posting it.

The patch should be safe because all changes are under #ifdef. Furthermore
the feature can be enabled or disabled at runtime by the `free_tuple_memory'
options in the pg_options file. The option is disabled by default and must
be explicitly enabled at runtime to have any effect.

To enable the patch add the follwing line to Makefile.custom:

CUSTOM_COPT += -DFREE_TUPLE_MEMORY

To enable the option at runtime add the following line to pg_option:

free_tuple_memory=1

Here is the patch:

*** src/include/utils/portal.h.orig	Wed May 26 09:07:16 1999
--- src/include/utils/portal.h	Fri Jun 11 18:06:07 1999
***************
*** 80,85 ****
--- 80,89 ----
  extern PortalVariableMemory PortalGetVariableMemory(Portal portal);
  extern PortalHeapMemory PortalGetHeapMemory(Portal portal);
+ #ifdef FREE_TUPLE_MEMORY
+ bool   PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer);
+ #endif
+ 
  /* estimate of the maximum number of open portals a user would have,
   * used in initially sizing the PortalHashTable in	EnablePortalManager()
   */
*** src/backend/utils/mmgr/portalmem.c.orig	Wed May 26 09:06:02 1999
--- src/backend/utils/mmgr/portalmem.c	Fri Jun 11 18:06:28 1999
***************
*** 289,294 ****
--- 289,312 ----
  	}
  }
+ #ifdef FREE_TUPLE_MEMORY
+ /*
+  * PortalHeapMemoryIsValid --
+  *
+  * Check if a pointer is allocated in a memory context.
+  *
+  */
+ bool
+ PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer)
+ {
+ 	HeapMemoryBlock block = HEAPMEMBLOCK((PortalHeapMemory) context);
+ 
+ 	AssertState(PointerIsValid(block));
+ 
+ 	return (AllocSetContains(&block->setData, pointer));
+ }
+ #endif
+ 
  /* ----------------
   *		PortalHeapMemoryRealloc
   * ----------------
*** src/include/utils/trace.h.orig	Sat Jun  5 09:00:40 1999
--- src/include/utils/trace.h	Fri Jun 11 19:01:30 1999
***************
*** 64,69 ****
--- 64,72 ----
  	OPT_SYSLOG,					/* use syslog for error messages */
  	OPT_HOSTLOOKUP,				/* enable hostname lookup in ps_status */
  	OPT_SHOWPORTNUMBER,			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	OPT_FREE_TUPLE_MEMORY,		/* try to pfree memory for each tuple */
+ #endif

NUM_PG_OPTIONS /* must be the last item of enum */
};
***************
*** 83,91 ****
#endif /* TRACE_H */

  /*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
   * End:
   */
--- 86,94 ----
  #endif	 /* TRACE_H */
  /*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
   * End:
   */
*** src/backend/utils/misc/trace.c.orig	Sat Jun  5 09:00:37 1999
--- src/backend/utils/misc/trace.c	Fri Jun 11 19:01:31 1999
***************
*** 73,78 ****
--- 73,81 ----
  	"syslog",					/* use syslog for error messages */
  	"hostlookup",				/* enable hostname lookup in ps_status */
  	"showportnumber",			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	"free_tuple_memory",		/* try to pfree memory for each tuple */
+ #endif

/* NUM_PG_OPTIONS */ /* must be the last item of enum */
};
***************
*** 404,412 ****
}

  /*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
   * End:
   */
--- 407,415 ----
  }
  /*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
   * End:
   */
*** src/backend/access/common/heaptuple.c.orig	Wed May 26 09:01:59 1999
--- src/backend/access/common/heaptuple.c	Fri Jun 11 19:08:33 1999
***************
*** 27,32 ****
--- 27,37 ----
  #include <storage/bufpage.h>
  #include <utils/memutils.h>
+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+ 
  #ifndef HAVE_MEMMOVE
  #include <regex/utils.h>
  #else
***************
*** 93,98 ****
--- 98,106 ----
  	int			i;
  	int			numberOfAttributes = tupleDesc->natts;
  	Form_pg_attribute *att = tupleDesc->attrs;
+ #ifdef FREE_TUPLE_MEMORY
+ 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
+ #endif
  	if (bit != NULL)
  	{
***************
*** 131,136 ****
--- 139,152 ----
  				*infomask |= HEAP_HASVARLENA;
  				data_length = VARSIZE(DatumGetPointer(value[i]));
  				memmove(data, DatumGetPointer(value[i]), data_length);
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree value[i] - dz */
+ 				if (free_tuple_memory &&
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) value[i])) {
+ 					pfree(value[i]);
+ 				}
+ #endif
  				break;
  			case sizeof(char):
  				*data = att[i]->attbyval ?
***************
*** 147,154 ****
  								   *((int32 *) value[i]));
  				break;
  			default:
! 				memmove(data, DatumGetPointer(value[i]),
! 						att[i]->attlen);
  				break;
  		}
  		data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
--- 163,177 ----
  								   *((int32 *) value[i]));
  				break;
  			default:
! 				memmove(data, DatumGetPointer(value[i]), att[i]->attlen);
! #ifdef FREE_TUPLE_MEMORY
! 				/* try to pfree value[i] - dz */
! 				if (free_tuple_memory &&
! 					PortalHeapMemoryIsValid(CurrentMemoryContext,
! 											(Pointer) value[i])) {
! 					pfree(value[i]);
! 				}
! #endif
  				break;
  		}
  		data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
*** src/backend/executor/nodeAgg.c.orig	Wed May 26 09:02:57 1999
--- src/backend/executor/nodeAgg.c	Fri Jun 11 19:10:27 1999
***************
*** 31,36 ****
--- 31,41 ----
  #include "utils/syscache.h"
  #include "optimizer/clauses.h"

+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+
/*
* AggFuncInfo -
* keeps the transition functions information around
***************
*** 113,119 ****
isNull1 = FALSE,
isNull2 = FALSE;
bool qual_result;
!

  	/* ---------------------
  	 *	get state info from node
--- 118,126 ----
  				isNull1 = FALSE,
  				isNull2 = FALSE;
  	bool		qual_result;
! #ifdef FREE_TUPLE_MEMORY
! 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
! #endif
  	/* ---------------------
  	 *	get state info from node
***************
*** 241,246 ****
--- 248,257 ----
  		for (;;)
  		{
  			TupleTableSlot *outerslot;
+ #ifdef FREE_TUPLE_MEMORY
+ 			Oid				valueType;
+ 			bool			isByValue = 0;
+ #endif
  			isNull = isNull1 = isNull2 = 0;
  			outerslot = ExecProcNode(outerPlan, (Plan *) node);
***************
*** 293,298 ****
--- 304,334 ----
  					newVal = ExecEvalExpr(aggref->target, econtext,
  										  &isNull, &isDone);
  				}
+ #ifdef FREE_TUPLE_MEMORY
+ 				if (free_tuple_memory) {
+ 					switch (nodeTag(aggref->target)) {
+ 					case T_Const:
+ 						isByValue = ((Const*) (aggref->target))->constbyval;
+ 						break;
+ 					case T_Var:
+ 						valueType = ((Var*) (aggref->target))->vartype;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					case T_Array:
+ 						isByValue = ((Array*)(aggref->target))->arrayelembyval;
+ 						break;
+ 					case T_ArrayRef:
+ 						isByValue =((ArrayRef*)(aggref->target))->refelembyval;
+ 						break;
+ 					case T_Expr:
+ 						valueType = ((Expr*) (aggref->target))->typeOid;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					default:
+ 						break;
+ 					}
+ 				}
+ #endif
  				if (isNull && !aggref->usenulls)
  					continue;	/* ignore this tuple for this agg */
***************
*** 353,358 ****
--- 389,404 ----
  										  (FmgrValues *) args, &isNull2);
  					Assert(!isNull2);
  				}
+ 
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree newVal if not isByValue - dz */
+ 				if (free_tuple_memory && !isByValue && 
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) newVal))
+ 				{
+ 					pfree(newVal);
+ 				}
+ #endif
  			}

/*

--
Massimo Dal Zotto

+----------------------------------------------------------------------+
|  Massimo Dal Zotto               email: dz@cs.unitn.it               |
|  Via Marconi, 141                phone: ++39-0461534251              |
|  38057 Pergine Valsugana (TN)      www: http://www.cs.unitn.it/~dz/  |
|  Italy                             pgp: finger dz@tango.cs.unitn.it  |
+----------------------------------------------------------------------+
#2Bruce Momjian
maillist@candle.pha.pa.us
In reply to: Massimo Dal Zotto (#1)
Re: patch for large queries

This looks like a great patch, and it is one of our major issues to fix
for 6.6.

Can I hold on to it, and put it in 6.5.1? I am pretty sure we will have
one. I am hesitant to put it in now because Marc would have to put out
a new beta for the change.

It looks really good.

Hi Hackers,

I don't like last minute patches before the final freeze, but I believe that
this one could be useful for people experiencing out-of-memory crashes while
executing queries which retrieve or use a very large number of tuples.

The problem happens when storage is allocated for functions results used in
a large query, for example:

select upper(name) from big_table;
select big_table.array[1] from big_table;
select count(upper(name)) from big_table;

This patch is a dirty hack that fixes the out-of-memory problem for the most
common cases, like the above ones. It is not the final solution for the
problem but it can work for some people, so I'm posting it.

The patch should be safe because all changes are under #ifdef. Furthermore
the feature can be enabled or disabled at runtime by the `free_tuple_memory'
options in the pg_options file. The option is disabled by default and must
be explicitly enabled at runtime to have any effect.

To enable the patch add the follwing line to Makefile.custom:

CUSTOM_COPT += -DFREE_TUPLE_MEMORY

To enable the option at runtime add the following line to pg_option:

free_tuple_memory=1

Here is the patch:

*** src/include/utils/portal.h.orig	Wed May 26 09:07:16 1999
--- src/include/utils/portal.h	Fri Jun 11 18:06:07 1999
***************
*** 80,85 ****
--- 80,89 ----
extern PortalVariableMemory PortalGetVariableMemory(Portal portal);
extern PortalHeapMemory PortalGetHeapMemory(Portal portal);
+ #ifdef FREE_TUPLE_MEMORY
+ bool   PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer);
+ #endif
+ 
/* estimate of the maximum number of open portals a user would have,
* used in initially sizing the PortalHashTable in	EnablePortalManager()
*/
*** src/backend/utils/mmgr/portalmem.c.orig	Wed May 26 09:06:02 1999
--- src/backend/utils/mmgr/portalmem.c	Fri Jun 11 18:06:28 1999
***************
*** 289,294 ****
--- 289,312 ----
}
}
+ #ifdef FREE_TUPLE_MEMORY
+ /*
+  * PortalHeapMemoryIsValid --
+  *
+  * Check if a pointer is allocated in a memory context.
+  *
+  */
+ bool
+ PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer)
+ {
+ 	HeapMemoryBlock block = HEAPMEMBLOCK((PortalHeapMemory) context);
+ 
+ 	AssertState(PointerIsValid(block));
+ 
+ 	return (AllocSetContains(&block->setData, pointer));
+ }
+ #endif
+ 
/* ----------------
*		PortalHeapMemoryRealloc
* ----------------
*** src/include/utils/trace.h.orig	Sat Jun  5 09:00:40 1999
--- src/include/utils/trace.h	Fri Jun 11 19:01:30 1999
***************
*** 64,69 ****
--- 64,72 ----
OPT_SYSLOG,					/* use syslog for error messages */
OPT_HOSTLOOKUP,				/* enable hostname lookup in ps_status */
OPT_SHOWPORTNUMBER,			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	OPT_FREE_TUPLE_MEMORY,		/* try to pfree memory for each tuple */
+ #endif

NUM_PG_OPTIONS /* must be the last item of enum */
};
***************
*** 83,91 ****
#endif /* TRACE_H */

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 86,94 ----
#endif	 /* TRACE_H */
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/utils/misc/trace.c.orig	Sat Jun  5 09:00:37 1999
--- src/backend/utils/misc/trace.c	Fri Jun 11 19:01:31 1999
***************
*** 73,78 ****
--- 73,81 ----
"syslog",					/* use syslog for error messages */
"hostlookup",				/* enable hostname lookup in ps_status */
"showportnumber",			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	"free_tuple_memory",		/* try to pfree memory for each tuple */
+ #endif

/* NUM_PG_OPTIONS */ /* must be the last item of enum */
};
***************
*** 404,412 ****
}

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 407,415 ----
}
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/access/common/heaptuple.c.orig	Wed May 26 09:01:59 1999
--- src/backend/access/common/heaptuple.c	Fri Jun 11 19:08:33 1999
***************
*** 27,32 ****
--- 27,37 ----
#include <storage/bufpage.h>
#include <utils/memutils.h>
+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+ 
#ifndef HAVE_MEMMOVE
#include <regex/utils.h>
#else
***************
*** 93,98 ****
--- 98,106 ----
int			i;
int			numberOfAttributes = tupleDesc->natts;
Form_pg_attribute *att = tupleDesc->attrs;
+ #ifdef FREE_TUPLE_MEMORY
+ 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
+ #endif
if (bit != NULL)
{
***************
*** 131,136 ****
--- 139,152 ----
*infomask |= HEAP_HASVARLENA;
data_length = VARSIZE(DatumGetPointer(value[i]));
memmove(data, DatumGetPointer(value[i]), data_length);
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree value[i] - dz */
+ 				if (free_tuple_memory &&
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) value[i])) {
+ 					pfree(value[i]);
+ 				}
+ #endif
break;
case sizeof(char):
*data = att[i]->attbyval ?
***************
*** 147,154 ****
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]),
! 						att[i]->attlen);
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
--- 163,177 ----
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]), att[i]->attlen);
! #ifdef FREE_TUPLE_MEMORY
! 				/* try to pfree value[i] - dz */
! 				if (free_tuple_memory &&
! 					PortalHeapMemoryIsValid(CurrentMemoryContext,
! 											(Pointer) value[i])) {
! 					pfree(value[i]);
! 				}
! #endif
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
*** src/backend/executor/nodeAgg.c.orig	Wed May 26 09:02:57 1999
--- src/backend/executor/nodeAgg.c	Fri Jun 11 19:10:27 1999
***************
*** 31,36 ****
--- 31,41 ----
#include "utils/syscache.h"
#include "optimizer/clauses.h"

+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+
/*
* AggFuncInfo -
* keeps the transition functions information around
***************
*** 113,119 ****
isNull1 = FALSE,
isNull2 = FALSE;
bool qual_result;
!

/* ---------------------
*	get state info from node
--- 118,126 ----
isNull1 = FALSE,
isNull2 = FALSE;
bool		qual_result;
! #ifdef FREE_TUPLE_MEMORY
! 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
! #endif
/* ---------------------
*	get state info from node
***************
*** 241,246 ****
--- 248,257 ----
for (;;)
{
TupleTableSlot *outerslot;
+ #ifdef FREE_TUPLE_MEMORY
+ 			Oid				valueType;
+ 			bool			isByValue = 0;
+ #endif
isNull = isNull1 = isNull2 = 0;
outerslot = ExecProcNode(outerPlan, (Plan *) node);
***************
*** 293,298 ****
--- 304,334 ----
newVal = ExecEvalExpr(aggref->target, econtext,
&isNull, &isDone);
}
+ #ifdef FREE_TUPLE_MEMORY
+ 				if (free_tuple_memory) {
+ 					switch (nodeTag(aggref->target)) {
+ 					case T_Const:
+ 						isByValue = ((Const*) (aggref->target))->constbyval;
+ 						break;
+ 					case T_Var:
+ 						valueType = ((Var*) (aggref->target))->vartype;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					case T_Array:
+ 						isByValue = ((Array*)(aggref->target))->arrayelembyval;
+ 						break;
+ 					case T_ArrayRef:
+ 						isByValue =((ArrayRef*)(aggref->target))->refelembyval;
+ 						break;
+ 					case T_Expr:
+ 						valueType = ((Expr*) (aggref->target))->typeOid;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					default:
+ 						break;
+ 					}
+ 				}
+ #endif
if (isNull && !aggref->usenulls)
continue;	/* ignore this tuple for this agg */
***************
*** 353,358 ****
--- 389,404 ----
(FmgrValues *) args, &isNull2);
Assert(!isNull2);
}
+ 
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree newVal if not isByValue - dz */
+ 				if (free_tuple_memory && !isByValue && 
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) newVal))
+ 				{
+ 					pfree(newVal);
+ 				}
+ #endif
}

/*

--
Massimo Dal Zotto

+----------------------------------------------------------------------+
|  Massimo Dal Zotto               email: dz@cs.unitn.it               |
|  Via Marconi, 141                phone: ++39-0461534251              |
|  38057 Pergine Valsugana (TN)      www: http://www.cs.unitn.it/~dz/  |
|  Italy                             pgp: finger dz@tango.cs.unitn.it  |
+----------------------------------------------------------------------+
-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
#3Bruce Momjian
maillist@candle.pha.pa.us
In reply to: Massimo Dal Zotto (#1)
Re: patch for large queries

Applied.

Hi Hackers,

I don't like last minute patches before the final freeze, but I believe that
this one could be useful for people experiencing out-of-memory crashes while
executing queries which retrieve or use a very large number of tuples.

The problem happens when storage is allocated for functions results used in
a large query, for example:

select upper(name) from big_table;
select big_table.array[1] from big_table;
select count(upper(name)) from big_table;

This patch is a dirty hack that fixes the out-of-memory problem for the most
common cases, like the above ones. It is not the final solution for the
problem but it can work for some people, so I'm posting it.

The patch should be safe because all changes are under #ifdef. Furthermore
the feature can be enabled or disabled at runtime by the `free_tuple_memory'
options in the pg_options file. The option is disabled by default and must
be explicitly enabled at runtime to have any effect.

To enable the patch add the follwing line to Makefile.custom:

CUSTOM_COPT += -DFREE_TUPLE_MEMORY

To enable the option at runtime add the following line to pg_option:

free_tuple_memory=1

Here is the patch:

*** src/include/utils/portal.h.orig	Wed May 26 09:07:16 1999
--- src/include/utils/portal.h	Fri Jun 11 18:06:07 1999
***************
*** 80,85 ****
--- 80,89 ----
extern PortalVariableMemory PortalGetVariableMemory(Portal portal);
extern PortalHeapMemory PortalGetHeapMemory(Portal portal);
+ #ifdef FREE_TUPLE_MEMORY
+ bool   PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer);
+ #endif
+ 
/* estimate of the maximum number of open portals a user would have,
* used in initially sizing the PortalHashTable in	EnablePortalManager()
*/
*** src/backend/utils/mmgr/portalmem.c.orig	Wed May 26 09:06:02 1999
--- src/backend/utils/mmgr/portalmem.c	Fri Jun 11 18:06:28 1999
***************
*** 289,294 ****
--- 289,312 ----
}
}
+ #ifdef FREE_TUPLE_MEMORY
+ /*
+  * PortalHeapMemoryIsValid --
+  *
+  * Check if a pointer is allocated in a memory context.
+  *
+  */
+ bool
+ PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer)
+ {
+ 	HeapMemoryBlock block = HEAPMEMBLOCK((PortalHeapMemory) context);
+ 
+ 	AssertState(PointerIsValid(block));
+ 
+ 	return (AllocSetContains(&block->setData, pointer));
+ }
+ #endif
+ 
/* ----------------
*		PortalHeapMemoryRealloc
* ----------------
*** src/include/utils/trace.h.orig	Sat Jun  5 09:00:40 1999
--- src/include/utils/trace.h	Fri Jun 11 19:01:30 1999
***************
*** 64,69 ****
--- 64,72 ----
OPT_SYSLOG,					/* use syslog for error messages */
OPT_HOSTLOOKUP,				/* enable hostname lookup in ps_status */
OPT_SHOWPORTNUMBER,			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	OPT_FREE_TUPLE_MEMORY,		/* try to pfree memory for each tuple */
+ #endif

NUM_PG_OPTIONS /* must be the last item of enum */
};
***************
*** 83,91 ****
#endif /* TRACE_H */

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 86,94 ----
#endif	 /* TRACE_H */
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/utils/misc/trace.c.orig	Sat Jun  5 09:00:37 1999
--- src/backend/utils/misc/trace.c	Fri Jun 11 19:01:31 1999
***************
*** 73,78 ****
--- 73,81 ----
"syslog",					/* use syslog for error messages */
"hostlookup",				/* enable hostname lookup in ps_status */
"showportnumber",			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	"free_tuple_memory",		/* try to pfree memory for each tuple */
+ #endif

/* NUM_PG_OPTIONS */ /* must be the last item of enum */
};
***************
*** 404,412 ****
}

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 407,415 ----
}
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/access/common/heaptuple.c.orig	Wed May 26 09:01:59 1999
--- src/backend/access/common/heaptuple.c	Fri Jun 11 19:08:33 1999
***************
*** 27,32 ****
--- 27,37 ----
#include <storage/bufpage.h>
#include <utils/memutils.h>
+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+ 
#ifndef HAVE_MEMMOVE
#include <regex/utils.h>
#else
***************
*** 93,98 ****
--- 98,106 ----
int			i;
int			numberOfAttributes = tupleDesc->natts;
Form_pg_attribute *att = tupleDesc->attrs;
+ #ifdef FREE_TUPLE_MEMORY
+ 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
+ #endif
if (bit != NULL)
{
***************
*** 131,136 ****
--- 139,152 ----
*infomask |= HEAP_HASVARLENA;
data_length = VARSIZE(DatumGetPointer(value[i]));
memmove(data, DatumGetPointer(value[i]), data_length);
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree value[i] - dz */
+ 				if (free_tuple_memory &&
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) value[i])) {
+ 					pfree(value[i]);
+ 				}
+ #endif
break;
case sizeof(char):
*data = att[i]->attbyval ?
***************
*** 147,154 ****
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]),
! 						att[i]->attlen);
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
--- 163,177 ----
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]), att[i]->attlen);
! #ifdef FREE_TUPLE_MEMORY
! 				/* try to pfree value[i] - dz */
! 				if (free_tuple_memory &&
! 					PortalHeapMemoryIsValid(CurrentMemoryContext,
! 											(Pointer) value[i])) {
! 					pfree(value[i]);
! 				}
! #endif
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
*** src/backend/executor/nodeAgg.c.orig	Wed May 26 09:02:57 1999
--- src/backend/executor/nodeAgg.c	Fri Jun 11 19:10:27 1999
***************
*** 31,36 ****
--- 31,41 ----
#include "utils/syscache.h"
#include "optimizer/clauses.h"

+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+
/*
* AggFuncInfo -
* keeps the transition functions information around
***************
*** 113,119 ****
isNull1 = FALSE,
isNull2 = FALSE;
bool qual_result;
!

/* ---------------------
*	get state info from node
--- 118,126 ----
isNull1 = FALSE,
isNull2 = FALSE;
bool		qual_result;
! #ifdef FREE_TUPLE_MEMORY
! 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
! #endif
/* ---------------------
*	get state info from node
***************
*** 241,246 ****
--- 248,257 ----
for (;;)
{
TupleTableSlot *outerslot;
+ #ifdef FREE_TUPLE_MEMORY
+ 			Oid				valueType;
+ 			bool			isByValue = 0;
+ #endif
isNull = isNull1 = isNull2 = 0;
outerslot = ExecProcNode(outerPlan, (Plan *) node);
***************
*** 293,298 ****
--- 304,334 ----
newVal = ExecEvalExpr(aggref->target, econtext,
&isNull, &isDone);
}
+ #ifdef FREE_TUPLE_MEMORY
+ 				if (free_tuple_memory) {
+ 					switch (nodeTag(aggref->target)) {
+ 					case T_Const:
+ 						isByValue = ((Const*) (aggref->target))->constbyval;
+ 						break;
+ 					case T_Var:
+ 						valueType = ((Var*) (aggref->target))->vartype;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					case T_Array:
+ 						isByValue = ((Array*)(aggref->target))->arrayelembyval;
+ 						break;
+ 					case T_ArrayRef:
+ 						isByValue =((ArrayRef*)(aggref->target))->refelembyval;
+ 						break;
+ 					case T_Expr:
+ 						valueType = ((Expr*) (aggref->target))->typeOid;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					default:
+ 						break;
+ 					}
+ 				}
+ #endif
if (isNull && !aggref->usenulls)
continue;	/* ignore this tuple for this agg */
***************
*** 353,358 ****
--- 389,404 ----
(FmgrValues *) args, &isNull2);
Assert(!isNull2);
}
+ 
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree newVal if not isByValue - dz */
+ 				if (free_tuple_memory && !isByValue && 
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) newVal))
+ 				{
+ 					pfree(newVal);
+ 				}
+ #endif
}

/*

--
Massimo Dal Zotto

+----------------------------------------------------------------------+
|  Massimo Dal Zotto               email: dz@cs.unitn.it               |
|  Via Marconi, 141                phone: ++39-0461534251              |
|  38057 Pergine Valsugana (TN)      www: http://www.cs.unitn.it/~dz/  |
|  Italy                             pgp: finger dz@tango.cs.unitn.it  |
+----------------------------------------------------------------------+
-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
#4Bruce Momjian
maillist@candle.pha.pa.us
In reply to: Massimo Dal Zotto (#1)
Re: patch for large queries

Sorry, someone objected, and I have to reverse out the patch. I will
keep it for later use when we address the issue.

Hi Hackers,

I don't like last minute patches before the final freeze, but I believe that
this one could be useful for people experiencing out-of-memory crashes while
executing queries which retrieve or use a very large number of tuples.

The problem happens when storage is allocated for functions results used in
a large query, for example:

select upper(name) from big_table;
select big_table.array[1] from big_table;
select count(upper(name)) from big_table;

This patch is a dirty hack that fixes the out-of-memory problem for the most
common cases, like the above ones. It is not the final solution for the
problem but it can work for some people, so I'm posting it.

The patch should be safe because all changes are under #ifdef. Furthermore
the feature can be enabled or disabled at runtime by the `free_tuple_memory'
options in the pg_options file. The option is disabled by default and must
be explicitly enabled at runtime to have any effect.

To enable the patch add the follwing line to Makefile.custom:

CUSTOM_COPT += -DFREE_TUPLE_MEMORY

To enable the option at runtime add the following line to pg_option:

free_tuple_memory=1

Here is the patch:

*** src/include/utils/portal.h.orig	Wed May 26 09:07:16 1999
--- src/include/utils/portal.h	Fri Jun 11 18:06:07 1999
***************
*** 80,85 ****
--- 80,89 ----
extern PortalVariableMemory PortalGetVariableMemory(Portal portal);
extern PortalHeapMemory PortalGetHeapMemory(Portal portal);
+ #ifdef FREE_TUPLE_MEMORY
+ bool   PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer);
+ #endif
+ 
/* estimate of the maximum number of open portals a user would have,
* used in initially sizing the PortalHashTable in	EnablePortalManager()
*/
*** src/backend/utils/mmgr/portalmem.c.orig	Wed May 26 09:06:02 1999
--- src/backend/utils/mmgr/portalmem.c	Fri Jun 11 18:06:28 1999
***************
*** 289,294 ****
--- 289,312 ----
}
}
+ #ifdef FREE_TUPLE_MEMORY
+ /*
+  * PortalHeapMemoryIsValid --
+  *
+  * Check if a pointer is allocated in a memory context.
+  *
+  */
+ bool
+ PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer)
+ {
+ 	HeapMemoryBlock block = HEAPMEMBLOCK((PortalHeapMemory) context);
+ 
+ 	AssertState(PointerIsValid(block));
+ 
+ 	return (AllocSetContains(&block->setData, pointer));
+ }
+ #endif
+ 
/* ----------------
*		PortalHeapMemoryRealloc
* ----------------
*** src/include/utils/trace.h.orig	Sat Jun  5 09:00:40 1999
--- src/include/utils/trace.h	Fri Jun 11 19:01:30 1999
***************
*** 64,69 ****
--- 64,72 ----
OPT_SYSLOG,					/* use syslog for error messages */
OPT_HOSTLOOKUP,				/* enable hostname lookup in ps_status */
OPT_SHOWPORTNUMBER,			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	OPT_FREE_TUPLE_MEMORY,		/* try to pfree memory for each tuple */
+ #endif

NUM_PG_OPTIONS /* must be the last item of enum */
};
***************
*** 83,91 ****
#endif /* TRACE_H */

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 86,94 ----
#endif	 /* TRACE_H */
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/utils/misc/trace.c.orig	Sat Jun  5 09:00:37 1999
--- src/backend/utils/misc/trace.c	Fri Jun 11 19:01:31 1999
***************
*** 73,78 ****
--- 73,81 ----
"syslog",					/* use syslog for error messages */
"hostlookup",				/* enable hostname lookup in ps_status */
"showportnumber",			/* show port number in ps_status */
+ #ifdef FREE_TUPLE_MEMORY
+ 	"free_tuple_memory",		/* try to pfree memory for each tuple */
+ #endif

/* NUM_PG_OPTIONS */ /* must be the last item of enum */
};
***************
*** 404,412 ****
}

/*
!  * Local variables:
!  *	tab-width: 4
!  *	c-indent-level: 4
!  *	c-basic-offset: 4
* End:
*/
--- 407,415 ----
}
/*
!  * Local Variables:
!  *  tab-width: 4
!  *  c-indent-level: 4
!  *  c-basic-offset: 4
* End:
*/
*** src/backend/access/common/heaptuple.c.orig	Wed May 26 09:01:59 1999
--- src/backend/access/common/heaptuple.c	Fri Jun 11 19:08:33 1999
***************
*** 27,32 ****
--- 27,37 ----
#include <storage/bufpage.h>
#include <utils/memutils.h>
+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+ 
#ifndef HAVE_MEMMOVE
#include <regex/utils.h>
#else
***************
*** 93,98 ****
--- 98,106 ----
int			i;
int			numberOfAttributes = tupleDesc->natts;
Form_pg_attribute *att = tupleDesc->attrs;
+ #ifdef FREE_TUPLE_MEMORY
+ 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
+ #endif
if (bit != NULL)
{
***************
*** 131,136 ****
--- 139,152 ----
*infomask |= HEAP_HASVARLENA;
data_length = VARSIZE(DatumGetPointer(value[i]));
memmove(data, DatumGetPointer(value[i]), data_length);
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree value[i] - dz */
+ 				if (free_tuple_memory &&
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) value[i])) {
+ 					pfree(value[i]);
+ 				}
+ #endif
break;
case sizeof(char):
*data = att[i]->attbyval ?
***************
*** 147,154 ****
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]),
! 						att[i]->attlen);
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
--- 163,177 ----
*((int32 *) value[i]));
break;
default:
! 				memmove(data, DatumGetPointer(value[i]), att[i]->attlen);
! #ifdef FREE_TUPLE_MEMORY
! 				/* try to pfree value[i] - dz */
! 				if (free_tuple_memory &&
! 					PortalHeapMemoryIsValid(CurrentMemoryContext,
! 											(Pointer) value[i])) {
! 					pfree(value[i]);
! 				}
! #endif
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);
*** src/backend/executor/nodeAgg.c.orig	Wed May 26 09:02:57 1999
--- src/backend/executor/nodeAgg.c	Fri Jun 11 19:10:27 1999
***************
*** 31,36 ****
--- 31,41 ----
#include "utils/syscache.h"
#include "optimizer/clauses.h"

+ #ifdef FREE_TUPLE_MEMORY
+ #include <utils/portal.h>
+ #include <utils/trace.h>
+ #endif
+
/*
* AggFuncInfo -
* keeps the transition functions information around
***************
*** 113,119 ****
isNull1 = FALSE,
isNull2 = FALSE;
bool qual_result;
!

/* ---------------------
*	get state info from node
--- 118,126 ----
isNull1 = FALSE,
isNull2 = FALSE;
bool		qual_result;
! #ifdef FREE_TUPLE_MEMORY
! 	bool		free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
! #endif
/* ---------------------
*	get state info from node
***************
*** 241,246 ****
--- 248,257 ----
for (;;)
{
TupleTableSlot *outerslot;
+ #ifdef FREE_TUPLE_MEMORY
+ 			Oid				valueType;
+ 			bool			isByValue = 0;
+ #endif
isNull = isNull1 = isNull2 = 0;
outerslot = ExecProcNode(outerPlan, (Plan *) node);
***************
*** 293,298 ****
--- 304,334 ----
newVal = ExecEvalExpr(aggref->target, econtext,
&isNull, &isDone);
}
+ #ifdef FREE_TUPLE_MEMORY
+ 				if (free_tuple_memory) {
+ 					switch (nodeTag(aggref->target)) {
+ 					case T_Const:
+ 						isByValue = ((Const*) (aggref->target))->constbyval;
+ 						break;
+ 					case T_Var:
+ 						valueType = ((Var*) (aggref->target))->vartype;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					case T_Array:
+ 						isByValue = ((Array*)(aggref->target))->arrayelembyval;
+ 						break;
+ 					case T_ArrayRef:
+ 						isByValue =((ArrayRef*)(aggref->target))->refelembyval;
+ 						break;
+ 					case T_Expr:
+ 						valueType = ((Expr*) (aggref->target))->typeOid;
+ 						isByValue = typeByVal(typeidType(valueType));
+ 						break;
+ 					default:
+ 						break;
+ 					}
+ 				}
+ #endif
if (isNull && !aggref->usenulls)
continue;	/* ignore this tuple for this agg */
***************
*** 353,358 ****
--- 389,404 ----
(FmgrValues *) args, &isNull2);
Assert(!isNull2);
}
+ 
+ #ifdef FREE_TUPLE_MEMORY
+ 				/* try to pfree newVal if not isByValue - dz */
+ 				if (free_tuple_memory && !isByValue && 
+ 					PortalHeapMemoryIsValid(CurrentMemoryContext,
+ 											(Pointer) newVal))
+ 				{
+ 					pfree(newVal);
+ 				}
+ #endif
}

/*

--
Massimo Dal Zotto

+----------------------------------------------------------------------+
|  Massimo Dal Zotto               email: dz@cs.unitn.it               |
|  Via Marconi, 141                phone: ++39-0461534251              |
|  38057 Pergine Valsugana (TN)      www: http://www.cs.unitn.it/~dz/  |
|  Italy                             pgp: finger dz@tango.cs.unitn.it  |
+----------------------------------------------------------------------+
-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026