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77a7e9968b
to make a reasonable attempt at accounting for palloc overhead, not just the requested size of each memory chunk. Since in many scenarios this will make for a significant reduction in the amount of space acquired, partially compensate by doubling the default value of SORT_MEM to 1Mb. Per discussion in pgsql-general around 9-Jun-2002..
77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* memnodes.h
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* POSTGRES memory context node definitions.
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*
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*
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: memnodes.h,v 1.25 2002/08/12 00:36:12 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef MEMNODES_H
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#define MEMNODES_H
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#include "nodes/nodes.h"
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/*
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* MemoryContext
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* A logical context in which memory allocations occur.
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*
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* MemoryContext itself is an abstract type that can have multiple
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* implementations, though for now we have only AllocSetContext.
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* The function pointers in MemoryContextMethods define one specific
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* implementation of MemoryContext --- they are a virtual function table
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* in C++ terms.
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*
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* Node types that are actual implementations of memory contexts must
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* begin with the same fields as MemoryContext.
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*
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* Note: for largely historical reasons, typedef MemoryContext is a pointer
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* to the context struct rather than the struct type itself.
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*/
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typedef struct MemoryContextMethods
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{
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void *(*alloc) (MemoryContext context, Size size);
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/* call this free_p in case someone #define's free() */
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void (*free_p) (MemoryContext context, void *pointer);
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void *(*realloc) (MemoryContext context, void *pointer, Size size);
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void (*init) (MemoryContext context);
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void (*reset) (MemoryContext context);
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void (*delete) (MemoryContext context);
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Size (*get_chunk_space) (MemoryContext context, void *pointer);
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void (*stats) (MemoryContext context);
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#ifdef MEMORY_CONTEXT_CHECKING
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void (*check) (MemoryContext context);
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#endif
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} MemoryContextMethods;
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typedef struct MemoryContextData
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{
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NodeTag type; /* identifies exact kind of context */
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MemoryContextMethods *methods; /* virtual function table */
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MemoryContext parent; /* NULL if no parent (toplevel context) */
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MemoryContext firstchild; /* head of linked list of children */
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MemoryContext nextchild; /* next child of same parent */
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char *name; /* context name (just for debugging) */
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} MemoryContextData;
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/* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
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/*
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* MemoryContextIsValid
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* True iff memory context is valid.
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*
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* Add new context types to the set accepted by this macro.
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*/
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#define MemoryContextIsValid(context) \
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((context) != NULL && \
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(IsA((context), AllocSetContext)))
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#endif /* MEMNODES_H */
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