PostgreSQL's memory management strategy (1)

As a large system software, if Memory Leakage is one of the key issues facing the system, PostgreSQL uses MemoryContext concept to solve this problem, first take a look at the definition of several data structures:

Note: In PostgreSQL code, general Struct will add suffix "data" with name, and the Struct's pointer is the name.

Typedef

Struct MemoryContextMethods

{

MemoryContext Context, Size Size;

/ * Call this free_p in case someone # define's free () * /

MemoryContext Context, Void * Pointer;

Void * (* Realloc) (MemoryContext Context, Void * Pointer, Size Size);

MemoryContext Context;

MemoryContext Context;

MemoryContext Context;

Size (* get_chunk_space) (MemoryContext Context, Void * Pointer);

(* is_empty) (MemoryContext Context);

"MemoryContext Context);

#ifdef memory_context_checking

MemoryContext Context;

#ENDIF

MemoryContextMethods;

Typedef

Struct MemoryContextData

{

Nodetag type; / * identifies exact kind of context * /

MemoryContextMethods * Methods; / * Virtual function table * /

MemoryContext Parent; / * null if no parent (topLEVEVEL Context) * /

MemoryContext firstchild; / * Head of linked list of children * /

MemoryContext Nextchild; / * Next child of Same Parent * /

Char * name; / * context name (just for debugging) * /

MemoryContextdata;

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