Pursuant to a pghackers discussion back around 11-Jul-00, get rid of aset.c's

not-very-good handling of mid-size allocation requests.  Do everything via
either the "small" case (chunk size rounded up to power of 2) or the "large"
case (pass it straight off to malloc()).  Increase the number of freelists
a little to set the breakpoint between these behaviors at 8K.

src/include/nodes/memnodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: memnodes.h,v 1.18 2000/07/11 14:30:34 momjian Exp $
+ * $Id: memnodes.h,v 1.19 2000/12/01 18:14:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -62,27 +62,6 @@ typedef struct MemoryContextData
 /* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
 
 
-/*
- * AllocSetContext is our standard implementation of MemoryContext.
- */
-typedef struct AllocBlockData *AllocBlock; /* internal to aset.c */
-typedef struct AllocChunkData *AllocChunk;
-
-typedef struct AllocSetContext
-{
-	MemoryContextData header;		/* Standard memory-context fields */
-	/* Info about storage allocated in this context: */
-	AllocBlock	blocks;				/* head of list of blocks in this set */
-#define ALLOCSET_NUM_FREELISTS	8
-	AllocChunk	freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
-	/* Allocation parameters for this context: */
-	Size		initBlockSize;		/* initial block size */
-	Size		maxBlockSize;		/* maximum block size */
-	AllocBlock	keeper;				/* if not NULL, keep this block
-									 * over resets */
-} AllocSetContext;
-
-
 /*
  * MemoryContextIsValid
  *		True iff memory context is valid.