Size of TOAST pointer
| От | Vignesh Raghunathan |
|---|---|
| Тема | Size of TOAST pointer |
| Дата | |
| Msg-id | CAD_AmVgQ6cHwCM_JoHH_vJmcLT6Q4tssNois1Un4AB=uXfVEBA@mail.gmail.com обсуждение исходный текст |
| Ответы |
Re: Size of TOAST pointer
|
| Список | pgsql-hackers |
Hello,
I was looking at the documentation for TOAST (http://www.postgresql.org/docs/devel/static/storage-toast.html) and it's specified that the toast pointer occupies 18 bytes. However, the struct representing the toast pointer is defined as follows
typedef struct varatt_external
{
int32 va_rawsize; /* Original data size (includes header) */
int32 va_extsize; /* External saved size (doesn't) */
Oid va_valueid; /* Unique ID of value within TOAST table */
Oid va_toastrelid; /* RelID of TOAST table containing it */
} varatt_external;
Assuming that the pointer is aligned to a 4 byte boundary, doesn't it sum up to 16 bytes?
Could someone please explain why the documentation specifies it as 18 bytes?
I am pretty new to the source code and the C language in general so I apologize if this question has an obvious answer.
Thanks,
Vignesh.
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