src/include/postgres.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * postgres.h
   4  *        Primary include file for PostgreSQL server .c files
   5  *
   6  * This should be the first file included by PostgreSQL backend modules.
   7  * Client-side code should include postgres_fe.h instead.
   8  *
   9  *
  10  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
  11  * Portions Copyright (c) 1995, Regents of the University of California
  12  *
  13  * src/include/postgres.h
  14  *
  15  *-------------------------------------------------------------------------
  16  */
  17 /*
  18  *----------------------------------------------------------------
  19  *       TABLE OF CONTENTS
  20  *
  21  *              When adding stuff to this file, please try to put stuff
  22  *              into the relevant section, or add new sections as appropriate.
  23  *
  24  *        section       description
  25  *        -------       ------------------------------------------------
  26  *              1)              variable-length datatypes (TOAST support)
  27  *              2)              Datum type + support macros
  28  *
  29  *       NOTES
  30  *
  31  *      In general, this file should contain declarations that are widely needed
  32  *      in the backend environment, but are of no interest outside the backend.
  33  *
  34  *      Simple type definitions live in c.h, where they are shared with
  35  *      postgres_fe.h.  We do that since those type definitions are needed by
  36  *      frontend modules that want to deal with binary data transmission to or
  37  *      from the backend.  Type definitions in this file should be for
  38  *      representations that never escape the backend, such as Datum or
  39  *      TOASTed varlena objects.
  40  *
  41  *----------------------------------------------------------------
  42  */
  43 #ifndef POSTGRES_H
  44 #define POSTGRES_H
  45
  46 #include "c.h"
  47 #include "utils/elog.h"
  48 #include "utils/palloc.h"
  49
  50 /* ----------------------------------------------------------------
  51  *                              Section 1:      variable-length datatypes (TOAST support)
  52  * ----------------------------------------------------------------
  53  */
  54
  55 /*
  56  * struct varatt_external is a traditional "TOAST pointer", that is, the
  57  * information needed to fetch a Datum stored out-of-line in a TOAST table.
  58  * The data is compressed if and only if the external size stored in
  59  * va_extinfo is less than va_rawsize - VARHDRSZ.
  60  *
  61  * This struct must not contain any padding, because we sometimes compare
  62  * these pointers using memcmp.
  63  *
  64  * Note that this information is stored unaligned within actual tuples, so
  65  * you need to memcpy from the tuple into a local struct variable before
  66  * you can look at these fields!  (The reason we use memcmp is to avoid
  67  * having to do that just to detect equality of two TOAST pointers...)
  68  */
  69 typedef struct varatt_external
  70 {
  71         int32           va_rawsize;             /* Original data size (includes header) */
  72         uint32          va_extinfo;             /* External saved size (without header) and
  73                                                                  * compression method */
  74         Oid                     va_valueid;             /* Unique ID of value within TOAST table */
  75         Oid                     va_toastrelid;  /* RelID of TOAST table containing it */
  76 }                       varatt_external;
  77
  78 /*
  79  * These macros define the "saved size" portion of va_extinfo.  Its remaining
  80  * two high-order bits identify the compression method.
  81  */
  82 #define VARLENA_EXTSIZE_BITS    30
  83 #define VARLENA_EXTSIZE_MASK    ((1U << VARLENA_EXTSIZE_BITS) - 1)
  84
  85 /*
  86  * struct varatt_indirect is a "TOAST pointer" representing an out-of-line
  87  * Datum that's stored in memory, not in an external toast relation.
  88  * The creator of such a Datum is entirely responsible that the referenced
  89  * storage survives for as long as referencing pointer Datums can exist.
  90  *
  91  * Note that just as for struct varatt_external, this struct is stored
  92  * unaligned within any containing tuple.
  93  */
  94 typedef struct varatt_indirect
  95 {
  96         struct varlena *pointer;        /* Pointer to in-memory varlena */
  97 }                       varatt_indirect;
  98
  99 /*
 100  * struct varatt_expanded is a "TOAST pointer" representing an out-of-line
 101  * Datum that is stored in memory, in some type-specific, not necessarily
 102  * physically contiguous format that is convenient for computation not
 103  * storage.  APIs for this, in particular the definition of struct
 104  * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
 105  *
 106  * Note that just as for struct varatt_external, this struct is stored
 107  * unaligned within any containing tuple.
 108  */
 109 typedef struct ExpandedObjectHeader ExpandedObjectHeader;
 110
 111 typedef struct varatt_expanded
 112 {
 113         ExpandedObjectHeader *eohptr;
 114 } varatt_expanded;
 115
 116 /*
 117  * Type tag for the various sorts of "TOAST pointer" datums.  The peculiar
 118  * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
 119  * with a previous notion that the tag field was the pointer datum's length.
 120  */
 121 typedef enum vartag_external
 122 {
 123         VARTAG_INDIRECT = 1,
 124         VARTAG_EXPANDED_RO = 2,
 125         VARTAG_EXPANDED_RW = 3,
 126         VARTAG_ONDISK = 18
 127 } vartag_external;
 128
 129 /* this test relies on the specific tag values above */
 130 #define VARTAG_IS_EXPANDED(tag) \
 131         (((tag) & ~1) == VARTAG_EXPANDED_RO)
 132
 133 #define VARTAG_SIZE(tag) \
 134         ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
 135          VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
 136          (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
 137          TrapMacro(true, "unrecognized TOAST vartag"))
 138
 139 /*
 140  * These structs describe the header of a varlena object that may have been
 141  * TOASTed.  Generally, don't reference these structs directly, but use the
 142  * macros below.
 143  *
 144  * We use separate structs for the aligned and unaligned cases because the
 145  * compiler might otherwise think it could generate code that assumes
 146  * alignment while touching fields of a 1-byte-header varlena.
 147  */
 148 typedef union
 149 {
 150         struct                                          /* Normal varlena (4-byte length) */
 151         {
 152                 uint32          va_header;
 153                 char            va_data[FLEXIBLE_ARRAY_MEMBER];
 154         }                       va_4byte;
 155         struct                                          /* Compressed-in-line format */
 156         {
 157                 uint32          va_header;
 158                 uint32          va_tcinfo;      /* Original data size (excludes header) and
 159                                                                  * compression method; see va_extinfo */
 160                 char            va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
 161         }                       va_compressed;
 162 } varattrib_4b;
 163
 164 typedef struct
 165 {
 166         uint8           va_header;
 167         char            va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
 168 } varattrib_1b;
 169
 170 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
 171 typedef struct
 172 {
 173         uint8           va_header;              /* Always 0x80 or 0x01 */
 174         uint8           va_tag;                 /* Type of datum */
 175         char            va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
 176 } varattrib_1b_e;
 177
 178 /*
 179  * Bit layouts for varlena headers on big-endian machines:
 180  *
 181  * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
 182  * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
 183  * 10000000 1-byte length word, unaligned, TOAST pointer
 184  * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
 185  *
 186  * Bit layouts for varlena headers on little-endian machines:
 187  *
 188  * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
 189  * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
 190  * 00000001 1-byte length word, unaligned, TOAST pointer
 191  * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
 192  *
 193  * The "xxx" bits are the length field (which includes itself in all cases).
 194  * In the big-endian case we mask to extract the length, in the little-endian
 195  * case we shift.  Note that in both cases the flag bits are in the physically
 196  * first byte.  Also, it is not possible for a 1-byte length word to be zero;
 197  * this lets us disambiguate alignment padding bytes from the start of an
 198  * unaligned datum.  (We now *require* pad bytes to be filled with zero!)
 199  *
 200  * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
 201  * the specific type and length of the pointer datum.
 202  */
 203
 204 /*
 205  * Endian-dependent macros.  These are considered internal --- use the
 206  * external macros below instead of using these directly.
 207  *
 208  * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
 209  * for such records. Hence you should usually check for IS_EXTERNAL before
 210  * checking for IS_1B.
 211  */
 212
 213 #ifdef WORDS_BIGENDIAN
 214
 215 #define VARATT_IS_4B(PTR) \
 216         ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
 217 #define VARATT_IS_4B_U(PTR) \
 218         ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
 219 #define VARATT_IS_4B_C(PTR) \
 220         ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
 221 #define VARATT_IS_1B(PTR) \
 222         ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
 223 #define VARATT_IS_1B_E(PTR) \
 224         ((((varattrib_1b *) (PTR))->va_header) == 0x80)
 225 #define VARATT_NOT_PAD_BYTE(PTR) \
 226         (*((uint8 *) (PTR)) != 0)
 227
 228 /* VARSIZE_4B() should only be used on known-aligned data */
 229 #define VARSIZE_4B(PTR) \
 230         (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
 231 #define VARSIZE_1B(PTR) \
 232         (((varattrib_1b *) (PTR))->va_header & 0x7F)
 233 #define VARTAG_1B_E(PTR) \
 234         (((varattrib_1b_e *) (PTR))->va_tag)
 235
 236 #define SET_VARSIZE_4B(PTR,len) \
 237         (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
 238 #define SET_VARSIZE_4B_C(PTR,len) \
 239         (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
 240 #define SET_VARSIZE_1B(PTR,len) \
 241         (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
 242 #define SET_VARTAG_1B_E(PTR,tag) \
 243         (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
 244          ((varattrib_1b_e *) (PTR))->va_tag = (tag))
 245
 246 #else                                                   /* !WORDS_BIGENDIAN */
 247
 248 #define VARATT_IS_4B(PTR) \
 249         ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
 250 #define VARATT_IS_4B_U(PTR) \
 251         ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
 252 #define VARATT_IS_4B_C(PTR) \
 253         ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
 254 #define VARATT_IS_1B(PTR) \
 255         ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
 256 #define VARATT_IS_1B_E(PTR) \
 257         ((((varattrib_1b *) (PTR))->va_header) == 0x01)
 258 #define VARATT_NOT_PAD_BYTE(PTR) \
 259         (*((uint8 *) (PTR)) != 0)
 260
 261 /* VARSIZE_4B() should only be used on known-aligned data */
 262 #define VARSIZE_4B(PTR) \
 263         ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
 264 #define VARSIZE_1B(PTR) \
 265         ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
 266 #define VARTAG_1B_E(PTR) \
 267         (((varattrib_1b_e *) (PTR))->va_tag)
 268
 269 #define SET_VARSIZE_4B(PTR,len) \
 270         (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
 271 #define SET_VARSIZE_4B_C(PTR,len) \
 272         (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
 273 #define SET_VARSIZE_1B(PTR,len) \
 274         (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
 275 #define SET_VARTAG_1B_E(PTR,tag) \
 276         (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
 277          ((varattrib_1b_e *) (PTR))->va_tag = (tag))
 278
 279 #endif                                                  /* WORDS_BIGENDIAN */
 280
 281 #define VARDATA_4B(PTR)         (((varattrib_4b *) (PTR))->va_4byte.va_data)
 282 #define VARDATA_4B_C(PTR)       (((varattrib_4b *) (PTR))->va_compressed.va_data)
 283 #define VARDATA_1B(PTR)         (((varattrib_1b *) (PTR))->va_data)
 284 #define VARDATA_1B_E(PTR)       (((varattrib_1b_e *) (PTR))->va_data)
 285
 286 /*
 287  * Externally visible TOAST macros begin here.
 288  */
 289
 290 #define VARHDRSZ_EXTERNAL               offsetof(varattrib_1b_e, va_data)
 291 #define VARHDRSZ_COMPRESSED             offsetof(varattrib_4b, va_compressed.va_data)
 292 #define VARHDRSZ_SHORT                  offsetof(varattrib_1b, va_data)
 293
 294 #define VARATT_SHORT_MAX                0x7F
 295 #define VARATT_CAN_MAKE_SHORT(PTR) \
 296         (VARATT_IS_4B_U(PTR) && \
 297          (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
 298 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
 299         (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
 300
 301 /*
 302  * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
 303  * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR().  Elsewhere, call
 304  * PG_DETOAST_DATUM(), VARDATA() and VARSIZE().  Directly fetching an int16,
 305  * int32 or wider field in the struct representing the datum layout requires
 306  * aligned data.  memcpy() is alignment-oblivious, as are most operations on
 307  * datatypes, such as text, whose layout struct contains only char fields.
 308  *
 309  * Code assembling a new datum should call VARDATA() and SET_VARSIZE().
 310  * (Datums begin life untoasted.)
 311  *
 312  * Other macros here should usually be used only by tuple assembly/disassembly
 313  * code and code that specifically wants to work with still-toasted Datums.
 314  */
 315 #define VARDATA(PTR)                                            VARDATA_4B(PTR)
 316 #define VARSIZE(PTR)                                            VARSIZE_4B(PTR)
 317
 318 #define VARSIZE_SHORT(PTR)                                      VARSIZE_1B(PTR)
 319 #define VARDATA_SHORT(PTR)                                      VARDATA_1B(PTR)
 320
 321 #define VARTAG_EXTERNAL(PTR)                            VARTAG_1B_E(PTR)
 322 #define VARSIZE_EXTERNAL(PTR)                           (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
 323 #define VARDATA_EXTERNAL(PTR)                           VARDATA_1B_E(PTR)
 324
 325 #define VARATT_IS_COMPRESSED(PTR)                       VARATT_IS_4B_C(PTR)
 326 #define VARATT_IS_EXTERNAL(PTR)                         VARATT_IS_1B_E(PTR)
 327 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
 328         (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
 329 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
 330         (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
 331 #define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \
 332         (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
 333 #define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
 334         (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
 335 #define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
 336         (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
 337 #define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \
 338         (VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
 339 #define VARATT_IS_SHORT(PTR)                            VARATT_IS_1B(PTR)
 340 #define VARATT_IS_EXTENDED(PTR)                         (!VARATT_IS_4B_U(PTR))
 341
 342 #define SET_VARSIZE(PTR, len)                           SET_VARSIZE_4B(PTR, len)
 343 #define SET_VARSIZE_SHORT(PTR, len)                     SET_VARSIZE_1B(PTR, len)
 344 #define SET_VARSIZE_COMPRESSED(PTR, len)        SET_VARSIZE_4B_C(PTR, len)
 345
 346 #define SET_VARTAG_EXTERNAL(PTR, tag)           SET_VARTAG_1B_E(PTR, tag)
 347
 348 #define VARSIZE_ANY(PTR) \
 349         (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
 350          (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
 351           VARSIZE_4B(PTR)))
 352
 353 /* Size of a varlena data, excluding header */
 354 #define VARSIZE_ANY_EXHDR(PTR) \
 355         (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
 356          (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
 357           VARSIZE_4B(PTR)-VARHDRSZ))
 358
 359 /* caution: this will not work on an external or compressed-in-line Datum */
 360 /* caution: this will return a possibly unaligned pointer */
 361 #define VARDATA_ANY(PTR) \
 362          (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
 363
 364 /* Decompressed size and compression method of an external compressed Datum */
 365 #define VARDATA_COMPRESSED_GET_EXTSIZE(PTR) \
 366         (((varattrib_4b *) (PTR))->va_compressed.va_tcinfo & VARLENA_EXTSIZE_MASK)
 367 #define VARDATA_COMPRESSED_GET_COMPRESS_METHOD(PTR) \
 368         (((varattrib_4b *) (PTR))->va_compressed.va_tcinfo >> VARLENA_EXTSIZE_BITS)
 369
 370 /* Same, when working directly with a struct varatt_external */
 371 #define VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) \
 372         ((toast_pointer).va_extinfo & VARLENA_EXTSIZE_MASK)
 373 #define VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer) \
 374         ((toast_pointer).va_extinfo >> VARLENA_EXTSIZE_BITS)
 375
 376 #define VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer, len, cm) \
 377         do { \
 378                 Assert((cm) == TOAST_PGLZ_COMPRESSION_ID || \
 379                            (cm) == TOAST_LZ4_COMPRESSION_ID); \
 380                 ((toast_pointer).va_extinfo = \
 381                         (len) | ((uint32) (cm) << VARLENA_EXTSIZE_BITS)); \
 382         } while (0)
 383
 384 /*
 385  * Testing whether an externally-stored value is compressed now requires
 386  * comparing size stored in va_extinfo (the actual length of the external data)
 387  * to rawsize (the original uncompressed datum's size).  The latter includes
 388  * VARHDRSZ overhead, the former doesn't.  We never use compression unless it
 389  * actually saves space, so we expect either equality or less-than.
 390  */
 391 #define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
 392         (VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) < \
 393          (toast_pointer).va_rawsize - VARHDRSZ)
 394
 395
 396 /* ----------------------------------------------------------------
 397  *                              Section 2:      Datum type + support macros
 398  * ----------------------------------------------------------------
 399  */
 400
 401 /*
 402  * A Datum contains either a value of a pass-by-value type or a pointer to a
 403  * value of a pass-by-reference type.  Therefore, we require:
 404  *
 405  * sizeof(Datum) == sizeof(void *) == 4 or 8
 406  *
 407  * The macros below and the analogous macros for other types should be used to
 408  * convert between a Datum and the appropriate C type.
 409  */
 410
 411 typedef uintptr_t Datum;
 412
 413 /*
 414  * A NullableDatum is used in places where both a Datum and its nullness needs
 415  * to be stored. This can be more efficient than storing datums and nullness
 416  * in separate arrays, due to better spatial locality, even if more space may
 417  * be wasted due to padding.
 418  */
 419 typedef struct NullableDatum
 420 {
 421 #define FIELDNO_NULLABLE_DATUM_DATUM 0
 422         Datum           value;
 423 #define FIELDNO_NULLABLE_DATUM_ISNULL 1
 424         bool            isnull;
 425         /* due to alignment padding this could be used for flags for free */
 426 } NullableDatum;
 427
 428 #define SIZEOF_DATUM SIZEOF_VOID_P
 429
 430 /*
 431  * DatumGetBool
 432  *              Returns boolean value of a datum.
 433  *
 434  * Note: any nonzero value will be considered true.
 435  */
 436
 437 #define DatumGetBool(X) ((bool) ((X) != 0))
 438
 439 /*
 440  * BoolGetDatum
 441  *              Returns datum representation for a boolean.
 442  *
 443  * Note: any nonzero value will be considered true.
 444  */
 445
 446 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
 447
 448 /*
 449  * DatumGetChar
 450  *              Returns character value of a datum.
 451  */
 452
 453 #define DatumGetChar(X) ((char) (X))
 454
 455 /*
 456  * CharGetDatum
 457  *              Returns datum representation for a character.
 458  */
 459
 460 #define CharGetDatum(X) ((Datum) (X))
 461
 462 /*
 463  * Int8GetDatum
 464  *              Returns datum representation for an 8-bit integer.
 465  */
 466
 467 #define Int8GetDatum(X) ((Datum) (X))
 468
 469 /*
 470  * DatumGetUInt8
 471  *              Returns 8-bit unsigned integer value of a datum.
 472  */
 473
 474 #define DatumGetUInt8(X) ((uint8) (X))
 475
 476 /*
 477  * UInt8GetDatum
 478  *              Returns datum representation for an 8-bit unsigned integer.
 479  */
 480
 481 #define UInt8GetDatum(X) ((Datum) (X))
 482
 483 /*
 484  * DatumGetInt16
 485  *              Returns 16-bit integer value of a datum.
 486  */
 487
 488 #define DatumGetInt16(X) ((int16) (X))
 489
 490 /*
 491  * Int16GetDatum
 492  *              Returns datum representation for a 16-bit integer.
 493  */
 494
 495 #define Int16GetDatum(X) ((Datum) (X))
 496
 497 /*
 498  * DatumGetUInt16
 499  *              Returns 16-bit unsigned integer value of a datum.
 500  */
 501
 502 #define DatumGetUInt16(X) ((uint16) (X))
 503
 504 /*
 505  * UInt16GetDatum
 506  *              Returns datum representation for a 16-bit unsigned integer.
 507  */
 508
 509 #define UInt16GetDatum(X) ((Datum) (X))
 510
 511 /*
 512  * DatumGetInt32
 513  *              Returns 32-bit integer value of a datum.
 514  */
 515
 516 #define DatumGetInt32(X) ((int32) (X))
 517
 518 /*
 519  * Int32GetDatum
 520  *              Returns datum representation for a 32-bit integer.
 521  */
 522
 523 #define Int32GetDatum(X) ((Datum) (X))
 524
 525 /*
 526  * DatumGetUInt32
 527  *              Returns 32-bit unsigned integer value of a datum.
 528  */
 529
 530 #define DatumGetUInt32(X) ((uint32) (X))
 531
 532 /*
 533  * UInt32GetDatum
 534  *              Returns datum representation for a 32-bit unsigned integer.
 535  */
 536
 537 #define UInt32GetDatum(X) ((Datum) (X))
 538
 539 /*
 540  * DatumGetObjectId
 541  *              Returns object identifier value of a datum.
 542  */
 543
 544 #define DatumGetObjectId(X) ((Oid) (X))
 545
 546 /*
 547  * ObjectIdGetDatum
 548  *              Returns datum representation for an object identifier.
 549  */
 550
 551 #define ObjectIdGetDatum(X) ((Datum) (X))
 552
 553 /*
 554  * DatumGetTransactionId
 555  *              Returns transaction identifier value of a datum.
 556  */
 557
 558 #define DatumGetTransactionId(X) ((TransactionId) (X))
 559
 560 /*
 561  * TransactionIdGetDatum
 562  *              Returns datum representation for a transaction identifier.
 563  */
 564
 565 #define TransactionIdGetDatum(X) ((Datum) (X))
 566
 567 /*
 568  * MultiXactIdGetDatum
 569  *              Returns datum representation for a multixact identifier.
 570  */
 571
 572 #define MultiXactIdGetDatum(X) ((Datum) (X))
 573
 574 /*
 575  * DatumGetCommandId
 576  *              Returns command identifier value of a datum.
 577  */
 578
 579 #define DatumGetCommandId(X) ((CommandId) (X))
 580
 581 /*
 582  * CommandIdGetDatum
 583  *              Returns datum representation for a command identifier.
 584  */
 585
 586 #define CommandIdGetDatum(X) ((Datum) (X))
 587
 588 /*
 589  * DatumGetPointer
 590  *              Returns pointer value of a datum.
 591  */
 592
 593 #define DatumGetPointer(X) ((Pointer) (X))
 594
 595 /*
 596  * PointerGetDatum
 597  *              Returns datum representation for a pointer.
 598  */
 599
 600 #define PointerGetDatum(X) ((Datum) (X))
 601
 602 /*
 603  * DatumGetCString
 604  *              Returns C string (null-terminated string) value of a datum.
 605  *
 606  * Note: C string is not a full-fledged Postgres type at present,
 607  * but type input functions use this conversion for their inputs.
 608  */
 609
 610 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
 611
 612 /*
 613  * CStringGetDatum
 614  *              Returns datum representation for a C string (null-terminated string).
 615  *
 616  * Note: C string is not a full-fledged Postgres type at present,
 617  * but type output functions use this conversion for their outputs.
 618  * Note: CString is pass-by-reference; caller must ensure the pointed-to
 619  * value has adequate lifetime.
 620  */
 621
 622 #define CStringGetDatum(X) PointerGetDatum(X)
 623
 624 /*
 625  * DatumGetName
 626  *              Returns name value of a datum.
 627  */
 628
 629 #define DatumGetName(X) ((Name) DatumGetPointer(X))
 630
 631 /*
 632  * NameGetDatum
 633  *              Returns datum representation for a name.
 634  *
 635  * Note: Name is pass-by-reference; caller must ensure the pointed-to
 636  * value has adequate lifetime.
 637  */
 638
 639 #define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
 640
 641 /*
 642  * DatumGetInt64
 643  *              Returns 64-bit integer value of a datum.
 644  *
 645  * Note: this macro hides whether int64 is pass by value or by reference.
 646  */
 647
 648 #ifdef USE_FLOAT8_BYVAL
 649 #define DatumGetInt64(X) ((int64) (X))
 650 #else
 651 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
 652 #endif
 653
 654 /*
 655  * Int64GetDatum
 656  *              Returns datum representation for a 64-bit integer.
 657  *
 658  * Note: if int64 is pass by reference, this function returns a reference
 659  * to palloc'd space.
 660  */
 661
 662 #ifdef USE_FLOAT8_BYVAL
 663 #define Int64GetDatum(X) ((Datum) (X))
 664 #else
 665 extern Datum Int64GetDatum(int64 X);
 666 #endif
 667
 668 /*
 669  * DatumGetUInt64
 670  *              Returns 64-bit unsigned integer value of a datum.
 671  *
 672  * Note: this macro hides whether int64 is pass by value or by reference.
 673  */
 674
 675 #ifdef USE_FLOAT8_BYVAL
 676 #define DatumGetUInt64(X) ((uint64) (X))
 677 #else
 678 #define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
 679 #endif
 680
 681 /*
 682  * UInt64GetDatum
 683  *              Returns datum representation for a 64-bit unsigned integer.
 684  *
 685  * Note: if int64 is pass by reference, this function returns a reference
 686  * to palloc'd space.
 687  */
 688
 689 #ifdef USE_FLOAT8_BYVAL
 690 #define UInt64GetDatum(X) ((Datum) (X))
 691 #else
 692 #define UInt64GetDatum(X) Int64GetDatum((int64) (X))
 693 #endif
 694
 695 /*
 696  * Float <-> Datum conversions
 697  *
 698  * These have to be implemented as inline functions rather than macros, when
 699  * passing by value, because many machines pass int and float function
 700  * parameters/results differently; so we need to play weird games with unions.
 701  */
 702
 703 /*
 704  * DatumGetFloat4
 705  *              Returns 4-byte floating point value of a datum.
 706  */
 707 static inline float4
 708 DatumGetFloat4(Datum X)
 709 {
 710         union
 711         {
 712                 int32           value;
 713                 float4          retval;
 714         }                       myunion;
 715
 716         myunion.value = DatumGetInt32(X);
 717         return myunion.retval;
 718 }
 719
 720 /*
 721  * Float4GetDatum
 722  *              Returns datum representation for a 4-byte floating point number.
 723  */
 724 static inline Datum
 725 Float4GetDatum(float4 X)
 726 {
 727         union
 728         {
 729                 float4          value;
 730                 int32           retval;
 731         }                       myunion;
 732
 733         myunion.value = X;
 734         return Int32GetDatum(myunion.retval);
 735 }
 736
 737 /*
 738  * DatumGetFloat8
 739  *              Returns 8-byte floating point value of a datum.
 740  *
 741  * Note: this macro hides whether float8 is pass by value or by reference.
 742  */
 743
 744 #ifdef USE_FLOAT8_BYVAL
 745 static inline float8
 746 DatumGetFloat8(Datum X)
 747 {
 748         union
 749         {
 750                 int64           value;
 751                 float8          retval;
 752         }                       myunion;
 753
 754         myunion.value = DatumGetInt64(X);
 755         return myunion.retval;
 756 }
 757 #else
 758 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
 759 #endif
 760
 761 /*
 762  * Float8GetDatum
 763  *              Returns datum representation for an 8-byte floating point number.
 764  *
 765  * Note: if float8 is pass by reference, this function returns a reference
 766  * to palloc'd space.
 767  */
 768
 769 #ifdef USE_FLOAT8_BYVAL
 770 static inline Datum
 771 Float8GetDatum(float8 X)
 772 {
 773         union
 774         {
 775                 float8          value;
 776                 int64           retval;
 777         }                       myunion;
 778
 779         myunion.value = X;
 780         return Int64GetDatum(myunion.retval);
 781 }
 782 #else
 783 extern Datum Float8GetDatum(float8 X);
 784 #endif
 785
 786
 787 /*
 788  * Int64GetDatumFast
 789  * Float8GetDatumFast
 790  *
 791  * These macros are intended to allow writing code that does not depend on
 792  * whether int64 and float8 are pass-by-reference types, while not
 793  * sacrificing performance when they are.  The argument must be a variable
 794  * that will exist and have the same value for as long as the Datum is needed.
 795  * In the pass-by-ref case, the address of the variable is taken to use as
 796  * the Datum.  In the pass-by-val case, these will be the same as the non-Fast
 797  * macros.
 798  */
 799
 800 #ifdef USE_FLOAT8_BYVAL
 801 #define Int64GetDatumFast(X)  Int64GetDatum(X)
 802 #define Float8GetDatumFast(X) Float8GetDatum(X)
 803 #else
 804 #define Int64GetDatumFast(X)  PointerGetDatum(&(X))
 805 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
 806 #endif
 807
 808 #endif                                                  /* POSTGRES_H */