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postgres/src/include/postgres.h
Fujii Masao 4cbd128328 Fix typos in comments.
2014-07-07 19:39:42 +09:00

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/*-------------------------------------------------------------------------
*
* postgres.h
* Primary include file for PostgreSQL server .c files
*
* This should be the first file included by PostgreSQL backend modules.
* Client-side code should include postgres_fe.h instead.
*
*
* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
* Portions Copyright (c) 1995, Regents of the University of California
*
* src/include/postgres.h
*
*-------------------------------------------------------------------------
*/
/*
*----------------------------------------------------------------
* TABLE OF CONTENTS
*
* When adding stuff to this file, please try to put stuff
* into the relevant section, or add new sections as appropriate.
*
* section description
* ------- ------------------------------------------------
* 1) variable-length datatypes (TOAST support)
* 2) datum type + support macros
* 3) exception handling backend support
*
* NOTES
*
* In general, this file should contain declarations that are widely needed
* in the backend environment, but are of no interest outside the backend.
*
* Simple type definitions live in c.h, where they are shared with
* postgres_fe.h. We do that since those type definitions are needed by
* frontend modules that want to deal with binary data transmission to or
* from the backend. Type definitions in this file should be for
* representations that never escape the backend, such as Datum or
* TOASTed varlena objects.
*
*----------------------------------------------------------------
*/
#ifndef POSTGRES_H
#define POSTGRES_H
#include "c.h"
#include "utils/elog.h"
#include "utils/palloc.h"
/* ----------------------------------------------------------------
* Section 1: variable-length datatypes (TOAST support)
* ----------------------------------------------------------------
*/
/*
* struct varatt_external is a "TOAST pointer", that is, the information needed
* to fetch a Datum stored in an out-of-line on-disk Datum. The data is
* compressed if and only if va_extsize < va_rawsize - VARHDRSZ. This struct
* must not contain any padding, because we sometimes compare pointers using
* memcmp.
*
* Note that this information is stored unaligned within actual tuples, so
* you need to memcpy from the tuple into a local struct variable before
* you can look at these fields! (The reason we use memcmp is to avoid
* having to do that just to detect equality of two TOAST pointers...)
*/
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;
/*
* Out-of-line Datum thats stored in memory in contrast to varatt_external
* pointers which points to data in an external toast relation.
*
* Note that just as varatt_external's this is stored unaligned within the
* tuple.
*/
typedef struct varatt_indirect
{
struct varlena *pointer; /* Pointer to in-memory varlena */
} varatt_indirect;
/*
* Type of external toast datum stored. The peculiar value for VARTAG_ONDISK
* comes from the requirement for on-disk compatibility with the older
* definitions of varattrib_1b_e where v_tag was named va_len_1be...
*/
typedef enum vartag_external
{
VARTAG_INDIRECT = 1,
VARTAG_ONDISK = 18
} vartag_external;
#define VARTAG_SIZE(tag) \
((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
(tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
TrapMacro(true, "unknown vartag"))
/*
* These structs describe the header of a varlena object that may have been
* TOASTed. Generally, don't reference these structs directly, but use the
* macros below.
*
* We use separate structs for the aligned and unaligned cases because the
* compiler might otherwise think it could generate code that assumes
* alignment while touching fields of a 1-byte-header varlena.
*/
typedef union
{
struct /* Normal varlena (4-byte length) */
{
uint32 va_header;
char va_data[1];
} va_4byte;
struct /* Compressed-in-line format */
{
uint32 va_header;
uint32 va_rawsize; /* Original data size (excludes header) */
char va_data[1]; /* Compressed data */
} va_compressed;
} varattrib_4b;
typedef struct
{
uint8 va_header;
char va_data[1]; /* Data begins here */
} varattrib_1b;
/* inline portion of a short varlena pointing to an external resource */
typedef struct
{
uint8 va_header; /* Always 0x80 or 0x01 */
uint8 va_tag; /* Type of datum */
char va_data[1]; /* Data (of the type indicated by va_tag) */
} varattrib_1b_e;
/*
* Bit layouts for varlena headers on big-endian machines:
*
* 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
* 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
* 10000000 1-byte length word, unaligned, TOAST pointer
* 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
*
* Bit layouts for varlena headers on little-endian machines:
*
* xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
* xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
* 00000001 1-byte length word, unaligned, TOAST pointer
* xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
*
* The "xxx" bits are the length field (which includes itself in all cases).
* In the big-endian case we mask to extract the length, in the little-endian
* case we shift. Note that in both cases the flag bits are in the physically
* first byte. Also, it is not possible for a 1-byte length word to be zero;
* this lets us disambiguate alignment padding bytes from the start of an
* unaligned datum. (We now *require* pad bytes to be filled with zero!)
*
* In TOAST datums the tag field in varattrib_1b_e is used to discern whether
* its an indirection pointer or more commonly an on-disk tuple.
*/
/*
* Endian-dependent macros. These are considered internal --- use the
* external macros below instead of using these directly.
*
* Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
* for such records. Hence you should usually check for IS_EXTERNAL before
* checking for IS_1B.
*/
#ifdef WORDS_BIGENDIAN
#define VARATT_IS_4B(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
#define VARATT_IS_4B_U(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
#define VARATT_IS_4B_C(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
#define VARATT_IS_1B(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
#define VARATT_IS_1B_E(PTR) \
((((varattrib_1b *) (PTR))->va_header) == 0x80)
#define VARATT_NOT_PAD_BYTE(PTR) \
(*((uint8 *) (PTR)) != 0)
/* VARSIZE_4B() should only be used on known-aligned data */
#define VARSIZE_4B(PTR) \
(((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
#define VARSIZE_1B(PTR) \
(((varattrib_1b *) (PTR))->va_header & 0x7F)
#define VARTAG_1B_E(PTR) \
(((varattrib_1b_e *) (PTR))->va_tag)
#define SET_VARSIZE_4B(PTR,len) \
(((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
#define SET_VARSIZE_4B_C(PTR,len) \
(((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
#define SET_VARSIZE_1B(PTR,len) \
(((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
#define SET_VARTAG_1B_E(PTR,tag) \
(((varattrib_1b_e *) (PTR))->va_header = 0x80, \
((varattrib_1b_e *) (PTR))->va_tag = (tag))
#else /* !WORDS_BIGENDIAN */
#define VARATT_IS_4B(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
#define VARATT_IS_4B_U(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
#define VARATT_IS_4B_C(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
#define VARATT_IS_1B(PTR) \
((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
#define VARATT_IS_1B_E(PTR) \
((((varattrib_1b *) (PTR))->va_header) == 0x01)
#define VARATT_NOT_PAD_BYTE(PTR) \
(*((uint8 *) (PTR)) != 0)
/* VARSIZE_4B() should only be used on known-aligned data */
#define VARSIZE_4B(PTR) \
((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
#define VARSIZE_1B(PTR) \
((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
#define VARTAG_1B_E(PTR) \
(((varattrib_1b_e *) (PTR))->va_tag)
#define SET_VARSIZE_4B(PTR,len) \
(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
#define SET_VARSIZE_4B_C(PTR,len) \
(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
#define SET_VARSIZE_1B(PTR,len) \
(((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
#define SET_VARTAG_1B_E(PTR,tag) \
(((varattrib_1b_e *) (PTR))->va_header = 0x01, \
((varattrib_1b_e *) (PTR))->va_tag = (tag))
#endif /* WORDS_BIGENDIAN */
#define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
#define VARATT_SHORT_MAX 0x7F
#define VARATT_CAN_MAKE_SHORT(PTR) \
(VARATT_IS_4B_U(PTR) && \
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
#define VARATT_CONVERTED_SHORT_SIZE(PTR) \
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
#define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
#define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
#define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
#define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
#define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
#define VARRAWSIZE_4B_C(PTR) \
(((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
/* Externally visible macros */
/*
* VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
* for varlena datatypes. Note that they only work on untoasted,
* 4-byte-header Datums!
*
* Code that wants to use 1-byte-header values without detoasting should
* use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY. The other macros here
* should usually be used only by tuple assembly/disassembly code and
* code that specifically wants to work with still-toasted Datums.
*
* WARNING: It is only safe to use VARDATA_ANY() -- typically with
* PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
* Either because you're working with something like text where the alignment
* doesn't matter or because you're not going to access its constituent parts
* and just use things like memcpy on it anyways.
*/
#define VARDATA(PTR) VARDATA_4B(PTR)
#define VARSIZE(PTR) VARSIZE_4B(PTR)
#define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
#define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
#define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
#define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
#define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
#define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
#define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
#define VARATT_IS_EXTERNAL_ONDISK(PTR) \
(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
#define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
#define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
#define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
#define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
#define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
#define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
#define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
#define VARSIZE_ANY(PTR) \
(VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
(VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
VARSIZE_4B(PTR)))
/* Size of a varlena data, excluding header */
#define VARSIZE_ANY_EXHDR(PTR) \
(VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
(VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
VARSIZE_4B(PTR)-VARHDRSZ))
/* caution: this will not work on an external or compressed-in-line Datum */
/* caution: this will return a possibly unaligned pointer */
#define VARDATA_ANY(PTR) \
(VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
/* ----------------------------------------------------------------
* Section 2: datum type + support macros
* ----------------------------------------------------------------
*/
/*
* Port Notes:
* Postgres makes the following assumptions about datatype sizes:
*
* sizeof(Datum) == sizeof(void *) == 4 or 8
* sizeof(char) == 1
* sizeof(short) == 2
*
* When a type narrower than Datum is stored in a Datum, we place it in the
* low-order bits and are careful that the DatumGetXXX macro for it discards
* the unused high-order bits (as opposed to, say, assuming they are zero).
* This is needed to support old-style user-defined functions, since depending
* on architecture and compiler, the return value of a function returning char
* or short may contain garbage when called as if it returned Datum.
*/
typedef uintptr_t Datum;
#define SIZEOF_DATUM SIZEOF_VOID_P
typedef Datum *DatumPtr;
#define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
#define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
#define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
#if SIZEOF_DATUM == 8
#define GET_8_BYTES(datum) ((Datum) (datum))
#endif
#define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
#define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
#define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)
#if SIZEOF_DATUM == 8
#define SET_8_BYTES(value) ((Datum) (value))
#endif
/*
* DatumGetBool
* Returns boolean value of a datum.
*
* Note: any nonzero value will be considered TRUE, but we ignore bits to
* the left of the width of bool, per comment above.
*/
#define DatumGetBool(X) ((bool) (((bool) (X)) != 0))
/*
* BoolGetDatum
* Returns datum representation for a boolean.
*
* Note: any nonzero value will be considered TRUE.
*/
#define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
/*
* DatumGetChar
* Returns character value of a datum.
*/
#define DatumGetChar(X) ((char) GET_1_BYTE(X))
/*
* CharGetDatum
* Returns datum representation for a character.
*/
#define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
/*
* Int8GetDatum
* Returns datum representation for an 8-bit integer.
*/
#define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
/*
* DatumGetUInt8
* Returns 8-bit unsigned integer value of a datum.
*/
#define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
/*
* UInt8GetDatum
* Returns datum representation for an 8-bit unsigned integer.
*/
#define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
/*
* DatumGetInt16
* Returns 16-bit integer value of a datum.
*/
#define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
/*
* Int16GetDatum
* Returns datum representation for a 16-bit integer.
*/
#define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
/*
* DatumGetUInt16
* Returns 16-bit unsigned integer value of a datum.
*/
#define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
/*
* UInt16GetDatum
* Returns datum representation for a 16-bit unsigned integer.
*/
#define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
/*
* DatumGetInt32
* Returns 32-bit integer value of a datum.
*/
#define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
/*
* Int32GetDatum
* Returns datum representation for a 32-bit integer.
*/
#define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
/*
* DatumGetUInt32
* Returns 32-bit unsigned integer value of a datum.
*/
#define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
/*
* UInt32GetDatum
* Returns datum representation for a 32-bit unsigned integer.
*/
#define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
/*
* DatumGetObjectId
* Returns object identifier value of a datum.
*/
#define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
/*
* ObjectIdGetDatum
* Returns datum representation for an object identifier.
*/
#define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
/*
* DatumGetTransactionId
* Returns transaction identifier value of a datum.
*/
#define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
/*
* TransactionIdGetDatum
* Returns datum representation for a transaction identifier.
*/
#define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
/*
* MultiXactIdGetDatum
* Returns datum representation for a multixact identifier.
*/
#define MultiXactIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
/*
* DatumGetCommandId
* Returns command identifier value of a datum.
*/
#define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
/*
* CommandIdGetDatum
* Returns datum representation for a command identifier.
*/
#define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
/*
* DatumGetPointer
* Returns pointer value of a datum.
*/
#define DatumGetPointer(X) ((Pointer) (X))
/*
* PointerGetDatum
* Returns datum representation for a pointer.
*/
#define PointerGetDatum(X) ((Datum) (X))
/*
* DatumGetCString
* Returns C string (null-terminated string) value of a datum.
*
* Note: C string is not a full-fledged Postgres type at present,
* but type input functions use this conversion for their inputs.
*/
#define DatumGetCString(X) ((char *) DatumGetPointer(X))
/*
* CStringGetDatum
* Returns datum representation for a C string (null-terminated string).
*
* Note: C string is not a full-fledged Postgres type at present,
* but type output functions use this conversion for their outputs.
* Note: CString is pass-by-reference; caller must ensure the pointed-to
* value has adequate lifetime.
*/
#define CStringGetDatum(X) PointerGetDatum(X)
/*
* DatumGetName
* Returns name value of a datum.
*/
#define DatumGetName(X) ((Name) DatumGetPointer(X))
/*
* NameGetDatum
* Returns datum representation for a name.
*
* Note: Name is pass-by-reference; caller must ensure the pointed-to
* value has adequate lifetime.
*/
#define NameGetDatum(X) PointerGetDatum(X)
/*
* DatumGetInt64
* Returns 64-bit integer value of a datum.
*
* Note: this macro hides whether int64 is pass by value or by reference.
*/
#ifdef USE_FLOAT8_BYVAL
#define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
#else
#define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
#endif
/*
* Int64GetDatum
* Returns datum representation for a 64-bit integer.
*
* Note: if int64 is pass by reference, this function returns a reference
* to palloc'd space.
*/
#ifdef USE_FLOAT8_BYVAL
#define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
#else
extern Datum Int64GetDatum(int64 X);
#endif
/*
* DatumGetFloat4
* Returns 4-byte floating point value of a datum.
*
* Note: this macro hides whether float4 is pass by value or by reference.
*/
#ifdef USE_FLOAT4_BYVAL
extern float4 DatumGetFloat4(Datum X);
#else
#define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
#endif
/*
* Float4GetDatum
* Returns datum representation for a 4-byte floating point number.
*
* Note: if float4 is pass by reference, this function returns a reference
* to palloc'd space.
*/
extern Datum Float4GetDatum(float4 X);
/*
* DatumGetFloat8
* Returns 8-byte floating point value of a datum.
*
* Note: this macro hides whether float8 is pass by value or by reference.
*/
#ifdef USE_FLOAT8_BYVAL
extern float8 DatumGetFloat8(Datum X);
#else
#define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
#endif
/*
* Float8GetDatum
* Returns datum representation for an 8-byte floating point number.
*
* Note: if float8 is pass by reference, this function returns a reference
* to palloc'd space.
*/
extern Datum Float8GetDatum(float8 X);
/*
* Int64GetDatumFast
* Float8GetDatumFast
* Float4GetDatumFast
*
* These macros are intended to allow writing code that does not depend on
* whether int64, float8, float4 are pass-by-reference types, while not
* sacrificing performance when they are. The argument must be a variable
* that will exist and have the same value for as long as the Datum is needed.
* In the pass-by-ref case, the address of the variable is taken to use as
* the Datum. In the pass-by-val case, these will be the same as the non-Fast
* macros.
*/
#ifdef USE_FLOAT8_BYVAL
#define Int64GetDatumFast(X) Int64GetDatum(X)
#define Float8GetDatumFast(X) Float8GetDatum(X)
#else
#define Int64GetDatumFast(X) PointerGetDatum(&(X))
#define Float8GetDatumFast(X) PointerGetDatum(&(X))
#endif
#ifdef USE_FLOAT4_BYVAL
#define Float4GetDatumFast(X) Float4GetDatum(X)
#else
#define Float4GetDatumFast(X) PointerGetDatum(&(X))
#endif
/* ----------------------------------------------------------------
* Section 3: exception handling backend support
* ----------------------------------------------------------------
*/
/*
* Backend only infrastructure for the assertion-related macros in c.h.
*
* ExceptionalCondition must be present even when assertions are not enabled.
*/
extern void ExceptionalCondition(const char *conditionName,
const char *errorType,
const char *fileName, int lineNumber) __attribute__((noreturn));
#endif /* POSTGRES_H */
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