greenplumn postgres 源码
greenplumn postgres 代码
文件路径：/src/include/postgres.h
/*-------------------------------------------------------------------------
*
* 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) 1996-2019, 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
*
* 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"
#include "storage/itemptr.h"
/* ----------------------------------------------------------------
* Section 1: variable-length datatypes (TOAST support)
* ----------------------------------------------------------------
*/
/*
* struct varatt_external is a traditional "TOAST pointer", that is, the
* information needed to fetch a Datum stored out-of-line in a TOAST table.
* The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ.
* This struct must not contain any padding, because we sometimes compare
* these 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;
/*
* struct varatt_indirect is a "TOAST pointer" representing an out-of-line
* Datum that's stored in memory, not in an external toast relation.
* The creator of such a Datum is entirely responsible that the referenced
* storage survives for as long as referencing pointer Datums can exist.
*
* Note that just as for struct varatt_external, this struct is stored
* unaligned within any containing tuple.
*/
typedef struct varatt_indirect
{
struct varlena *pointer; /* Pointer to in-memory varlena */
} varatt_indirect;
/*
* struct varatt_expanded is a "TOAST pointer" representing an out-of-line
* Datum that is stored in memory, in some type-specific, not necessarily
* physically contiguous format that is convenient for computation not
* storage. APIs for this, in particular the definition of struct
* ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
*
* Note that just as for struct varatt_external, this struct is stored
* unaligned within any containing tuple.
*/
typedef struct ExpandedObjectHeader ExpandedObjectHeader;
typedef struct varatt_expanded
{
ExpandedObjectHeader *eohptr;
} varatt_expanded;
/*
* Type tag for the various sorts of "TOAST pointer" datums. The peculiar
* value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
* with a previous notion that the tag field was the pointer datum's length.
*
* GPDB: In PostgreSQL VARTAG_ONDISK is set to 18 in order to match the
* historic (VARHDRSZ_EXTERNAL + sizeof(struct varatt_external)) value of the
* pointer datum's length. In Greenplum VARHDRSZ_EXTERNAL is two bytes longer
* than PostgreSQL due to extra padding in varattrib_1b_e, so VARTAG_ONDISK has
* to be set to 20.
*/
typedef enum vartag_external
{
VARTAG_INDIRECT = 1,
VARTAG_EXPANDED_RO = 2,
VARTAG_EXPANDED_RW = 3,
VARTAG_ONDISK = 20
} vartag_external;
/* this test relies on the specific tag values above */
#define VARTAG_IS_EXPANDED(tag) \
(((tag) & ~1) == VARTAG_EXPANDED_RO)
#define VARTAG_SIZE(tag) \
((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
(tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
TrapMacro(true, "unrecognized TOAST 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[FLEXIBLE_ARRAY_MEMBER];
} va_4byte;
struct /* Compressed-in-line format */
{
uint32 va_header;
uint32 va_rawsize; /* Original data size (excludes header) */
char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
} va_compressed;
} varattrib_4b;
typedef struct
{
uint8 va_header;
char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
} varattrib_1b;
/* NOT Like Postgres! ...In GPDB, We waste a few bytes of padding */
/* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
typedef struct
{
uint8 va_header; /* Always 0x80 */
uint8 va_tag; /* Type of datum */
uint8 va_padding[2]; /*** GPDB only: Alignment padding ***/
char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
} varattrib_1b_e;
/*
* Bit layouts for varlena headers: (GPDB always stores this big-endian format)
*
* 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)
*
* Greenplum differs from PostgreSQL here... In Postgres, they use different
* macros for big-endian and little-endian machines, so the length is contiguous,
* while the 4 byte lengths are stored in native endian format.
*
* Greenplum stored the 4 byte varlena header in network byte order, so it always
* look big-endian in the tuple. This is a bit ugly, but changing it would require
* all our customers to initdb.
*
* The "xxx" bits are the length field (which includes itself in all cases).
* In the big-endian case we mask to extract the length.
* 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 pointers the va_tag field (see varattrib_1b_e) is used to discern
* the specific type and length of the pointer datum.
*/
/*
* 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.
*/
#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) \
(ntohl(((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 = htonl( (len) & 0x3FFFFFFF ))
#define SET_VARSIZE_4B_C(PTR,len) \
(((varattrib_4b *) (PTR))->va_4byte.va_header = htonl( ((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))
#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)
/* In Postgres, this is 2, but in GPDB, it's 4, due to padding */
#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 */
/*
* In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
* VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR(). Elsewhere, call
* PG_DETOAST_DATUM(), VARDATA() and VARSIZE(). Directly fetching an int16,
* int32 or wider field in the struct representing the datum layout requires
* aligned data. memcpy() is alignment-oblivious, as are most operations on
* datatypes, such as text, whose layout struct contains only char fields.
*
* Code assembling a new datum should call VARDATA() and SET_VARSIZE().
* (Datums begin life untoasted.)
*
* Other macros here should usually be used only by tuple assembly/disassembly
* code and code that specifically wants to work with still-toasted Datums.
*/
#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_EXTERNAL_EXPANDED_RO(PTR) \
(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
#define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
#define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
(VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
#define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \
(VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
#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
* ----------------------------------------------------------------
*/
/*
* A Datum contains either a value of a pass-by-value type or a pointer to a
* value of a pass-by-reference type. Therefore, we require:
*
* sizeof(Datum) == sizeof(void *) == 4 or 8
*
* Greenplum CDB:
* Datum is always 8 bytes, regardless if it is 32bit or 64bit machine.
* so may be > sizeof(void *). To align with postgres, which defines Datum as
* uintptr_t type, it is defined as a uintptr_t to make sure the raw Datum
* comparator work. GPDB's document requires a x86_64 environment where
* uintptr_t is 64bits which doesn't violate the original 64bits definition.
* Although it is unclear why did GPDB had that restriction at the beginning.
*
* The macros below and the analogous macros for other types should be used to
* convert between a Datum and the appropriate C type.
*/
typedef uintptr_t Datum;
typedef union Datum_U
{
Datum d;
float4 f4[2];
float8 f8;
void *ptr;
} Datum_U;
#define SIZEOF_DATUM 8
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
/*
* A NullableDatum is used in places where both a Datum and its nullness needs
* to be stored. This can be more efficient than storing datums and nullness
* in separate arrays, due to better spatial locality, even if more space may
* be wasted due to padding.
*/
typedef struct NullableDatum
{
#define FIELDNO_NULLABLE_DATUM_DATUM 0
Datum value;
#define FIELDNO_NULLABLE_DATUM_ISNULL 1
bool isnull;
/* due to alignment padding this could be used for flags for free */
} NullableDatum;
/*
* Conversion between Datum and type X. Changed from Macro to static inline
* functions to get proper type checking.
*/
/*
* DatumGetBool
* Returns boolean value of a datum.
*
* Note: any nonzero value will be considered true.
*/
static inline bool DatumGetBool(Datum d) { return ((bool)d) != 0; }
static inline Datum BoolGetDatum(bool b) { return (b ? 1 : 0); }
static inline char DatumGetChar(Datum d) { return (char) d; }
static inline Datum CharGetDatum(char c) { return (Datum) c; }
static inline int8 DatumGetInt8(Datum d) { return (int8) d; }
static inline Datum Int8GetDatum(int8 i8) { return (Datum) i8; }
static inline uint8 DatumGetUInt8(Datum d) { return (uint8) d; }
static inline Datum UInt8GetDatum(uint8 ui8) { return (Datum) ui8; }
static inline int16 DatumGetInt16(Datum d) { return (int16) d; }
static inline Datum Int16GetDatum(int16 i16) { return (Datum) i16; }
static inline uint16 DatumGetUInt16(Datum d) { return (uint16) d; }
static inline Datum UInt16GetDatum(uint16 ui16) { return (Datum) ui16; }
static inline int32 DatumGetInt32(Datum d) { return (int32) d; }
static inline Datum Int32GetDatum(int32 i32) { return (Datum) i32; }
static inline uint32 DatumGetUInt32(Datum d) { return (uint32) d; }
static inline Datum UInt32GetDatum(uint32 ui32) { return (Datum) ui32; }
static inline int64 DatumGetInt64(Datum d) { return (int64) d; }
static inline Datum Int64GetDatum(int64 i64) { return (Datum) i64; }
static inline Datum Int64GetDatumFast(int64 x) { return Int64GetDatum(x); }
/*
* DatumGetUInt64
* Returns 64-bit unsigned integer value of a datum.
*
* Note: this macro hides whether int64 is pass by value or by reference.
*/
#ifdef USE_FLOAT8_BYVAL
#define DatumGetUInt64(X) ((uint64) (X))
#else
#define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
#endif
/*
* UInt64GetDatum
* Returns datum representation for a 64-bit unsigned integer.
*
* Note: if int64 is pass by reference, this function returns a reference
* to palloc'd space.
*/
#ifdef USE_FLOAT8_BYVAL
#define UInt64GetDatum(X) ((Datum) (X))
#else
#define UInt64GetDatum(X) Int64GetDatum((int64) (X))
#endif
static inline Oid DatumGetObjectId(Datum d) { return (Oid) d; }
static inline Datum ObjectIdGetDatum(Oid oid) { return (Datum) oid; }
static inline TransactionId DatumGetTransactionId(Datum d) { return (TransactionId) d; }
static inline Datum TransactionIdGetDatum(TransactionId tid) { return (Datum) tid; }
static inline TransactionId DatumGetMultiXactId(Datum d) { return (TransactionId) d; }
static inline Datum MultiXactIdGetDatum(TransactionId tid) { return (Datum) tid; }
static inline CommandId DatumGetCommandId(Datum d) { return (CommandId) d; }
static inline Datum CommandIdGetDatum(CommandId cid) { return (Datum) cid; }
/*
* DatumGetPointer
* Returns pointer value of a datum.
*/
#define DatumGetPointer(X) ((Pointer) (X))
/*
* PointerGetDatum
* Returns datum representation for a pointer.
*/
#define PointerGetDatum(X) ((Datum) (X))
static inline char *DatumGetCString(Datum d) { return (char* ) DatumGetPointer(d); }
static inline Datum CStringGetDatum(const char *p) { return PointerGetDatum(p); }
static inline Name DatumGetName(Datum d) { return (Name) DatumGetPointer(d); }
static inline Datum NameGetDatum(const Name n) { return PointerGetDatum(n); }
#ifndef WORDS_BIGENDIAN
static inline float4 DatumGetFloat4(Datum d) { Datum_U du; du.d = d; return du.f4[0]; }
static inline Datum Float4GetDatum(float4 f) { Datum_U du; du.d = 0; du.f4[0] = f; return du.d; }
#else
static inline float4 DatumGetFloat4(Datum d) { Datum_U du; du.d = d; return du.f4[1]; }
static inline Datum Float4GetDatum(float4 f) { Datum_U du; du.d = 0; du.f4[1] = f; return du.d; }
#endif
static inline float8 DatumGetFloat8(Datum d) { Datum_U du; du.d = d; return du.f8; }
static inline Datum Float8GetDatum(float8 f) { Datum_U du; du.f8 = f; return du.d; }
static inline Datum Float8GetDatumFast(float8 f) { return Float8GetDatum(f); }
static inline ItemPointer DatumGetItemPointer(Datum d) { return (ItemPointer) DatumGetPointer(d); }
static inline Datum ItemPointerGetDatum(ItemPointer i) { return PointerGetDatum(i); }
static inline bool IsAligned(void *p, int align)
{
int64 i = (int64) PointerGetDatum(p);
return ((i & (align-1)) == 0);
}
/* ----------------------------------------------------------------
* Section 3: exception handling backend support
* ----------------------------------------------------------------
*/
#define COMPILE_ASSERT(e) ((void)sizeof(char[1-2*!(e)]))
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
/*
* 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) pg_attribute_noreturn();
#endif /* POSTGRES_H */
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