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postgres.h
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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) 1996-2018, 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 va_extsize < va_rawsize - VARHDRSZ.
59  * This struct must not contain any padding, because we sometimes compare
60  * these pointers using memcmp.
61  *
62  * Note that this information is stored unaligned within actual tuples, so
63  * you need to memcpy from the tuple into a local struct variable before
64  * you can look at these fields! (The reason we use memcmp is to avoid
65  * having to do that just to detect equality of two TOAST pointers...)
66  */
67 typedef struct varatt_external
68 {
69  int32 va_rawsize; /* Original data size (includes header) */
70  int32 va_extsize; /* External saved size (doesn't) */
71  Oid va_valueid; /* Unique ID of value within TOAST table */
72  Oid va_toastrelid; /* RelID of TOAST table containing it */
74 
75 /*
76  * struct varatt_indirect is a "TOAST pointer" representing an out-of-line
77  * Datum that's stored in memory, not in an external toast relation.
78  * The creator of such a Datum is entirely responsible that the referenced
79  * storage survives for as long as referencing pointer Datums can exist.
80  *
81  * Note that just as for struct varatt_external, this struct is stored
82  * unaligned within any containing tuple.
83  */
84 typedef struct varatt_indirect
85 {
86  struct varlena *pointer; /* Pointer to in-memory varlena */
88 
89 /*
90  * struct varatt_expanded is a "TOAST pointer" representing an out-of-line
91  * Datum that is stored in memory, in some type-specific, not necessarily
92  * physically contiguous format that is convenient for computation not
93  * storage. APIs for this, in particular the definition of struct
94  * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
95  *
96  * Note that just as for struct varatt_external, this struct is stored
97  * unaligned within any containing tuple.
98  */
100 
101 typedef struct varatt_expanded
102 {
105 
106 /*
107  * Type tag for the various sorts of "TOAST pointer" datums. The peculiar
108  * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
109  * with a previous notion that the tag field was the pointer datum's length.
110  */
111 typedef enum vartag_external
112 {
118 
119 /* this test relies on the specific tag values above */
120 #define VARTAG_IS_EXPANDED(tag) \
121  (((tag) & ~1) == VARTAG_EXPANDED_RO)
122 
123 #define VARTAG_SIZE(tag) \
124  ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
125  VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
126  (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
127  TrapMacro(true, "unrecognized TOAST vartag"))
128 
129 /*
130  * These structs describe the header of a varlena object that may have been
131  * TOASTed. Generally, don't reference these structs directly, but use the
132  * macros below.
133  *
134  * We use separate structs for the aligned and unaligned cases because the
135  * compiler might otherwise think it could generate code that assumes
136  * alignment while touching fields of a 1-byte-header varlena.
137  */
138 typedef union
139 {
140  struct /* Normal varlena (4-byte length) */
141  {
143  char va_data[FLEXIBLE_ARRAY_MEMBER];
144  } va_4byte;
145  struct /* Compressed-in-line format */
146  {
147  uint32 va_header;
148  uint32 va_rawsize; /* Original data size (excludes header) */
149  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
150  } va_compressed;
151 } varattrib_4b;
152 
153 typedef struct
154 {
156  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
157 } varattrib_1b;
158 
159 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
160 typedef struct
161 {
162  uint8 va_header; /* Always 0x80 or 0x01 */
163  uint8 va_tag; /* Type of datum */
164  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
166 
167 /*
168  * Bit layouts for varlena headers on big-endian machines:
169  *
170  * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
171  * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
172  * 10000000 1-byte length word, unaligned, TOAST pointer
173  * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
174  *
175  * Bit layouts for varlena headers on little-endian machines:
176  *
177  * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
178  * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
179  * 00000001 1-byte length word, unaligned, TOAST pointer
180  * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
181  *
182  * The "xxx" bits are the length field (which includes itself in all cases).
183  * In the big-endian case we mask to extract the length, in the little-endian
184  * case we shift. Note that in both cases the flag bits are in the physically
185  * first byte. Also, it is not possible for a 1-byte length word to be zero;
186  * this lets us disambiguate alignment padding bytes from the start of an
187  * unaligned datum. (We now *require* pad bytes to be filled with zero!)
188  *
189  * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
190  * the specific type and length of the pointer datum.
191  */
192 
193 /*
194  * Endian-dependent macros. These are considered internal --- use the
195  * external macros below instead of using these directly.
196  *
197  * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
198  * for such records. Hence you should usually check for IS_EXTERNAL before
199  * checking for IS_1B.
200  */
201 
202 #ifdef WORDS_BIGENDIAN
203 
204 #define VARATT_IS_4B(PTR) \
205  ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
206 #define VARATT_IS_4B_U(PTR) \
207  ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
208 #define VARATT_IS_4B_C(PTR) \
209  ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
210 #define VARATT_IS_1B(PTR) \
211  ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
212 #define VARATT_IS_1B_E(PTR) \
213  ((((varattrib_1b *) (PTR))->va_header) == 0x80)
214 #define VARATT_NOT_PAD_BYTE(PTR) \
215  (*((uint8 *) (PTR)) != 0)
216 
217 /* VARSIZE_4B() should only be used on known-aligned data */
218 #define VARSIZE_4B(PTR) \
219  (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
220 #define VARSIZE_1B(PTR) \
221  (((varattrib_1b *) (PTR))->va_header & 0x7F)
222 #define VARTAG_1B_E(PTR) \
223  (((varattrib_1b_e *) (PTR))->va_tag)
224 
225 #define SET_VARSIZE_4B(PTR,len) \
226  (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
227 #define SET_VARSIZE_4B_C(PTR,len) \
228  (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
229 #define SET_VARSIZE_1B(PTR,len) \
230  (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
231 #define SET_VARTAG_1B_E(PTR,tag) \
232  (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
233  ((varattrib_1b_e *) (PTR))->va_tag = (tag))
234 #else /* !WORDS_BIGENDIAN */
235 
236 #define VARATT_IS_4B(PTR) \
237  ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
238 #define VARATT_IS_4B_U(PTR) \
239  ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
240 #define VARATT_IS_4B_C(PTR) \
241  ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
242 #define VARATT_IS_1B(PTR) \
243  ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
244 #define VARATT_IS_1B_E(PTR) \
245  ((((varattrib_1b *) (PTR))->va_header) == 0x01)
246 #define VARATT_NOT_PAD_BYTE(PTR) \
247  (*((uint8 *) (PTR)) != 0)
248 
249 /* VARSIZE_4B() should only be used on known-aligned data */
250 #define VARSIZE_4B(PTR) \
251  ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
252 #define VARSIZE_1B(PTR) \
253  ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
254 #define VARTAG_1B_E(PTR) \
255  (((varattrib_1b_e *) (PTR))->va_tag)
256 
257 #define SET_VARSIZE_4B(PTR,len) \
258  (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
259 #define SET_VARSIZE_4B_C(PTR,len) \
260  (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
261 #define SET_VARSIZE_1B(PTR,len) \
262  (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
263 #define SET_VARTAG_1B_E(PTR,tag) \
264  (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
265  ((varattrib_1b_e *) (PTR))->va_tag = (tag))
266 #endif /* WORDS_BIGENDIAN */
267 
268 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
269 #define VARATT_SHORT_MAX 0x7F
270 #define VARATT_CAN_MAKE_SHORT(PTR) \
271  (VARATT_IS_4B_U(PTR) && \
272  (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
273 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
274  (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
275 
276 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
277 
278 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
279 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
280 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
281 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
282 
283 #define VARRAWSIZE_4B_C(PTR) \
284  (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
285 
286 /* Externally visible macros */
287 
288 /*
289  * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
290  * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR(). Elsewhere, call
291  * PG_DETOAST_DATUM(), VARDATA() and VARSIZE(). Directly fetching an int16,
292  * int32 or wider field in the struct representing the datum layout requires
293  * aligned data. memcpy() is alignment-oblivious, as are most operations on
294  * datatypes, such as text, whose layout struct contains only char fields.
295  *
296  * Code assembling a new datum should call VARDATA() and SET_VARSIZE().
297  * (Datums begin life untoasted.)
298  *
299  * Other macros here should usually be used only by tuple assembly/disassembly
300  * code and code that specifically wants to work with still-toasted Datums.
301  */
302 #define VARDATA(PTR) VARDATA_4B(PTR)
303 #define VARSIZE(PTR) VARSIZE_4B(PTR)
304 
305 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
306 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
307 
308 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
309 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
310 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
311 
312 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
313 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
314 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
315  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
316 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
317  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
318 #define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \
319  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
320 #define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
321  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
322 #define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
323  (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
324 #define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \
325  (VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
326 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
327 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
328 
329 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
330 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
331 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
332 
333 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
334 
335 #define VARSIZE_ANY(PTR) \
336  (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
337  (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
338  VARSIZE_4B(PTR)))
339 
340 /* Size of a varlena data, excluding header */
341 #define VARSIZE_ANY_EXHDR(PTR) \
342  (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
343  (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
344  VARSIZE_4B(PTR)-VARHDRSZ))
345 
346 /* caution: this will not work on an external or compressed-in-line Datum */
347 /* caution: this will return a possibly unaligned pointer */
348 #define VARDATA_ANY(PTR) \
349  (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
350 
351 
352 /* ----------------------------------------------------------------
353  * Section 2: Datum type + support macros
354  * ----------------------------------------------------------------
355  */
356 
357 /*
358  * A Datum contains either a value of a pass-by-value type or a pointer to a
359  * value of a pass-by-reference type. Therefore, we require:
360  *
361  * sizeof(Datum) == sizeof(void *) == 4 or 8
362  *
363  * The macros below and the analogous macros for other types should be used to
364  * convert between a Datum and the appropriate C type.
365  */
366 
367 typedef uintptr_t Datum;
368 
369 #define SIZEOF_DATUM SIZEOF_VOID_P
370 
371 /*
372  * DatumGetBool
373  * Returns boolean value of a datum.
374  *
375  * Note: any nonzero value will be considered true.
376  */
377 
378 #define DatumGetBool(X) ((bool) ((X) != 0))
379 
380 /*
381  * BoolGetDatum
382  * Returns datum representation for a boolean.
383  *
384  * Note: any nonzero value will be considered true.
385  */
386 
387 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
388 
389 /*
390  * DatumGetChar
391  * Returns character value of a datum.
392  */
393 
394 #define DatumGetChar(X) ((char) (X))
395 
396 /*
397  * CharGetDatum
398  * Returns datum representation for a character.
399  */
400 
401 #define CharGetDatum(X) ((Datum) (X))
402 
403 /*
404  * Int8GetDatum
405  * Returns datum representation for an 8-bit integer.
406  */
407 
408 #define Int8GetDatum(X) ((Datum) (X))
409 
410 /*
411  * DatumGetUInt8
412  * Returns 8-bit unsigned integer value of a datum.
413  */
414 
415 #define DatumGetUInt8(X) ((uint8) (X))
416 
417 /*
418  * UInt8GetDatum
419  * Returns datum representation for an 8-bit unsigned integer.
420  */
421 
422 #define UInt8GetDatum(X) ((Datum) (X))
423 
424 /*
425  * DatumGetInt16
426  * Returns 16-bit integer value of a datum.
427  */
428 
429 #define DatumGetInt16(X) ((int16) (X))
430 
431 /*
432  * Int16GetDatum
433  * Returns datum representation for a 16-bit integer.
434  */
435 
436 #define Int16GetDatum(X) ((Datum) (X))
437 
438 /*
439  * DatumGetUInt16
440  * Returns 16-bit unsigned integer value of a datum.
441  */
442 
443 #define DatumGetUInt16(X) ((uint16) (X))
444 
445 /*
446  * UInt16GetDatum
447  * Returns datum representation for a 16-bit unsigned integer.
448  */
449 
450 #define UInt16GetDatum(X) ((Datum) (X))
451 
452 /*
453  * DatumGetInt32
454  * Returns 32-bit integer value of a datum.
455  */
456 
457 #define DatumGetInt32(X) ((int32) (X))
458 
459 /*
460  * Int32GetDatum
461  * Returns datum representation for a 32-bit integer.
462  */
463 
464 #define Int32GetDatum(X) ((Datum) (X))
465 
466 /*
467  * DatumGetUInt32
468  * Returns 32-bit unsigned integer value of a datum.
469  */
470 
471 #define DatumGetUInt32(X) ((uint32) (X))
472 
473 /*
474  * UInt32GetDatum
475  * Returns datum representation for a 32-bit unsigned integer.
476  */
477 
478 #define UInt32GetDatum(X) ((Datum) (X))
479 
480 /*
481  * DatumGetObjectId
482  * Returns object identifier value of a datum.
483  */
484 
485 #define DatumGetObjectId(X) ((Oid) (X))
486 
487 /*
488  * ObjectIdGetDatum
489  * Returns datum representation for an object identifier.
490  */
491 
492 #define ObjectIdGetDatum(X) ((Datum) (X))
493 
494 /*
495  * DatumGetTransactionId
496  * Returns transaction identifier value of a datum.
497  */
498 
499 #define DatumGetTransactionId(X) ((TransactionId) (X))
500 
501 /*
502  * TransactionIdGetDatum
503  * Returns datum representation for a transaction identifier.
504  */
505 
506 #define TransactionIdGetDatum(X) ((Datum) (X))
507 
508 /*
509  * MultiXactIdGetDatum
510  * Returns datum representation for a multixact identifier.
511  */
512 
513 #define MultiXactIdGetDatum(X) ((Datum) (X))
514 
515 /*
516  * DatumGetCommandId
517  * Returns command identifier value of a datum.
518  */
519 
520 #define DatumGetCommandId(X) ((CommandId) (X))
521 
522 /*
523  * CommandIdGetDatum
524  * Returns datum representation for a command identifier.
525  */
526 
527 #define CommandIdGetDatum(X) ((Datum) (X))
528 
529 /*
530  * DatumGetPointer
531  * Returns pointer value of a datum.
532  */
533 
534 #define DatumGetPointer(X) ((Pointer) (X))
535 
536 /*
537  * PointerGetDatum
538  * Returns datum representation for a pointer.
539  */
540 
541 #define PointerGetDatum(X) ((Datum) (X))
542 
543 /*
544  * DatumGetCString
545  * Returns C string (null-terminated string) value of a datum.
546  *
547  * Note: C string is not a full-fledged Postgres type at present,
548  * but type input functions use this conversion for their inputs.
549  */
550 
551 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
552 
553 /*
554  * CStringGetDatum
555  * Returns datum representation for a C string (null-terminated string).
556  *
557  * Note: C string is not a full-fledged Postgres type at present,
558  * but type output functions use this conversion for their outputs.
559  * Note: CString is pass-by-reference; caller must ensure the pointed-to
560  * value has adequate lifetime.
561  */
562 
563 #define CStringGetDatum(X) PointerGetDatum(X)
564 
565 /*
566  * DatumGetName
567  * Returns name value of a datum.
568  */
569 
570 #define DatumGetName(X) ((Name) DatumGetPointer(X))
571 
572 /*
573  * NameGetDatum
574  * Returns datum representation for a name.
575  *
576  * Note: Name is pass-by-reference; caller must ensure the pointed-to
577  * value has adequate lifetime.
578  */
579 
580 #define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
581 
582 /*
583  * DatumGetInt64
584  * Returns 64-bit integer value of a datum.
585  *
586  * Note: this macro hides whether int64 is pass by value or by reference.
587  */
588 
589 #ifdef USE_FLOAT8_BYVAL
590 #define DatumGetInt64(X) ((int64) (X))
591 #else
592 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
593 #endif
594 
595 /*
596  * Int64GetDatum
597  * Returns datum representation for a 64-bit integer.
598  *
599  * Note: if int64 is pass by reference, this function returns a reference
600  * to palloc'd space.
601  */
602 
603 #ifdef USE_FLOAT8_BYVAL
604 #define Int64GetDatum(X) ((Datum) (X))
605 #else
606 extern Datum Int64GetDatum(int64 X);
607 #endif
608 
609 /*
610  * DatumGetUInt64
611  * Returns 64-bit unsigned integer value of a datum.
612  *
613  * Note: this macro hides whether int64 is pass by value or by reference.
614  */
615 
616 #ifdef USE_FLOAT8_BYVAL
617 #define DatumGetUInt64(X) ((uint64) (X))
618 #else
619 #define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
620 #endif
621 
622 /*
623  * UInt64GetDatum
624  * Returns datum representation for a 64-bit unsigned integer.
625  *
626  * Note: if int64 is pass by reference, this function returns a reference
627  * to palloc'd space.
628  */
629 
630 #ifdef USE_FLOAT8_BYVAL
631 #define UInt64GetDatum(X) ((Datum) (X))
632 #else
633 #define UInt64GetDatum(X) Int64GetDatum((int64) (X))
634 #endif
635 
636 /*
637  * Float <-> Datum conversions
638  *
639  * These have to be implemented as inline functions rather than macros, when
640  * passing by value, because many machines pass int and float function
641  * parameters/results differently; so we need to play weird games with unions.
642  */
643 
644 /*
645  * DatumGetFloat4
646  * Returns 4-byte floating point value of a datum.
647  *
648  * Note: this macro hides whether float4 is pass by value or by reference.
649  */
650 
651 #ifdef USE_FLOAT4_BYVAL
652 static inline float4
654 {
655  union
656  {
657  int32 value;
658  float4 retval;
659  } myunion;
660 
661  myunion.value = DatumGetInt32(X);
662  return myunion.retval;
663 }
664 #else
665 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
666 #endif
667 
668 /*
669  * Float4GetDatum
670  * Returns datum representation for a 4-byte floating point number.
671  *
672  * Note: if float4 is pass by reference, this function returns a reference
673  * to palloc'd space.
674  */
675 #ifdef USE_FLOAT4_BYVAL
676 static inline Datum
678 {
679  union
680  {
681  float4 value;
682  int32 retval;
683  } myunion;
684 
685  myunion.value = X;
686  return Int32GetDatum(myunion.retval);
687 }
688 #else
689 extern Datum Float4GetDatum(float4 X);
690 #endif
691 
692 /*
693  * DatumGetFloat8
694  * Returns 8-byte floating point value of a datum.
695  *
696  * Note: this macro hides whether float8 is pass by value or by reference.
697  */
698 
699 #ifdef USE_FLOAT8_BYVAL
700 static inline float8
702 {
703  union
704  {
705  int64 value;
706  float8 retval;
707  } myunion;
708 
709  myunion.value = DatumGetInt64(X);
710  return myunion.retval;
711 }
712 #else
713 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
714 #endif
715 
716 /*
717  * Float8GetDatum
718  * Returns datum representation for an 8-byte floating point number.
719  *
720  * Note: if float8 is pass by reference, this function returns a reference
721  * to palloc'd space.
722  */
723 
724 #ifdef USE_FLOAT8_BYVAL
725 static inline Datum
727 {
728  union
729  {
730  float8 value;
731  int64 retval;
732  } myunion;
733 
734  myunion.value = X;
735  return Int64GetDatum(myunion.retval);
736 }
737 #else
738 extern Datum Float8GetDatum(float8 X);
739 #endif
740 
741 
742 /*
743  * Int64GetDatumFast
744  * Float8GetDatumFast
745  * Float4GetDatumFast
746  *
747  * These macros are intended to allow writing code that does not depend on
748  * whether int64, float8, float4 are pass-by-reference types, while not
749  * sacrificing performance when they are. The argument must be a variable
750  * that will exist and have the same value for as long as the Datum is needed.
751  * In the pass-by-ref case, the address of the variable is taken to use as
752  * the Datum. In the pass-by-val case, these will be the same as the non-Fast
753  * macros.
754  */
755 
756 #ifdef USE_FLOAT8_BYVAL
757 #define Int64GetDatumFast(X) Int64GetDatum(X)
758 #define Float8GetDatumFast(X) Float8GetDatum(X)
759 #else
760 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
761 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
762 #endif
763 
764 #ifdef USE_FLOAT4_BYVAL
765 #define Float4GetDatumFast(X) Float4GetDatum(X)
766 #else
767 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
768 #endif
769 
770 #endif /* POSTGRES_H */
vartag_external
Definition: postgres.h:111
ExpandedObjectHeader * eohptr
Definition: postgres.h:103
Datum Float4GetDatum(float4 X)
Definition: fmgr.c:1889
struct varatt_expanded varatt_expanded
#define DatumGetInt32(X)
Definition: postgres.h:457
uint8 va_tag
Definition: postgres.h:163
unsigned char uint8
Definition: c.h:323
Oid va_toastrelid
Definition: postgres.h:72
int32 va_rawsize
Definition: postgres.h:69
unsigned int Oid
Definition: postgres_ext.h:31
signed int int32
Definition: c.h:313
struct varatt_external varatt_external
double float8
Definition: c.h:458
Datum Float8GetDatum(float8 X)
Definition: fmgr.c:1901
#define DatumGetInt64(X)
Definition: postgres.h:592
unsigned int uint32
Definition: c.h:325
uint8 va_header
Definition: postgres.h:155
float float4
Definition: c.h:457
uint8 va_header
Definition: postgres.h:162
#define DatumGetFloat8(X)
Definition: postgres.h:713
uintptr_t Datum
Definition: postgres.h:367
static struct @131 value
int32 va_extsize
Definition: postgres.h:70
#define DatumGetFloat4(X)
Definition: postgres.h:665
uint32 va_header
Definition: postgres.h:142
struct varlena * pointer
Definition: postgres.h:86
#define Int32GetDatum(X)
Definition: postgres.h:464
uint32 va_rawsize
Definition: postgres.h:148
Datum Int64GetDatum(int64 X)
Definition: fmgr.c:1877
Definition: c.h:516
struct varatt_indirect varatt_indirect