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) 1996-2019, 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 */
67typedef 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 */
73} varatt_external;
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 */
84typedef struct varatt_indirect
85{
86 struct varlena *pointer; /* Pointer to in-memory varlena */
87} varatt_indirect;
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 */
99typedef struct ExpandedObjectHeader ExpandedObjectHeader;
100
101typedef struct varatt_expanded
102{
103 ExpandedObjectHeader *eohptr;
104} varatt_expanded;
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 */
111typedef enum vartag_external
112{
113 VARTAG_INDIRECT = 1,
114 VARTAG_EXPANDED_RO = 2,
115 VARTAG_EXPANDED_RW = 3,
116 VARTAG_ONDISK = 18
117} vartag_external;
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 */
138typedef union
139{
140 struct /* Normal varlena (4-byte length) */
141 {
142 uint32 va_header;
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
153typedef struct
154{
155 uint8 va_header;
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 */
160typedef 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 */
165} varattrib_1b_e;
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
367typedef uintptr_t Datum;
368
369/*
370 * A NullableDatum is used in places where both a Datum and its nullness needs
371 * to be stored. This can be more efficient than storing datums and nullness
372 * in separate arrays, due to better spatial locality, even if more space may
373 * be wasted due to padding.
374 */
375typedef struct NullableDatum
376{
377#define FIELDNO_NULLABLE_DATUM_DATUM 0
378 Datum value;
379#define FIELDNO_NULLABLE_DATUM_ISNULL 1
380 bool isnull;
381 /* due to alignment padding this could be used for flags for free */
382} NullableDatum;
383
384#define SIZEOF_DATUM SIZEOF_VOID_P
385
386/*
387 * DatumGetBool
388 * Returns boolean value of a datum.
389 *
390 * Note: any nonzero value will be considered true.
391 */
392
393#define DatumGetBool(X) ((bool) ((X) != 0))
394
395/*
396 * BoolGetDatum
397 * Returns datum representation for a boolean.
398 *
399 * Note: any nonzero value will be considered true.
400 */
401
402#define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
403
404/*
405 * DatumGetChar
406 * Returns character value of a datum.
407 */
408
409#define DatumGetChar(X) ((char) (X))
410
411/*
412 * CharGetDatum
413 * Returns datum representation for a character.
414 */
415
416#define CharGetDatum(X) ((Datum) (X))
417
418/*
419 * Int8GetDatum
420 * Returns datum representation for an 8-bit integer.
421 */
422
423#define Int8GetDatum(X) ((Datum) (X))
424
425/*
426 * DatumGetUInt8
427 * Returns 8-bit unsigned integer value of a datum.
428 */
429
430#define DatumGetUInt8(X) ((uint8) (X))
431
432/*
433 * UInt8GetDatum
434 * Returns datum representation for an 8-bit unsigned integer.
435 */
436
437#define UInt8GetDatum(X) ((Datum) (X))
438
439/*
440 * DatumGetInt16
441 * Returns 16-bit integer value of a datum.
442 */
443
444#define DatumGetInt16(X) ((int16) (X))
445
446/*
447 * Int16GetDatum
448 * Returns datum representation for a 16-bit integer.
449 */
450
451#define Int16GetDatum(X) ((Datum) (X))
452
453/*
454 * DatumGetUInt16
455 * Returns 16-bit unsigned integer value of a datum.
456 */
457
458#define DatumGetUInt16(X) ((uint16) (X))
459
460/*
461 * UInt16GetDatum
462 * Returns datum representation for a 16-bit unsigned integer.
463 */
464
465#define UInt16GetDatum(X) ((Datum) (X))
466
467/*
468 * DatumGetInt32
469 * Returns 32-bit integer value of a datum.
470 */
471
472#define DatumGetInt32(X) ((int32) (X))
473
474/*
475 * Int32GetDatum
476 * Returns datum representation for a 32-bit integer.
477 */
478
479#define Int32GetDatum(X) ((Datum) (X))
480
481/*
482 * DatumGetUInt32
483 * Returns 32-bit unsigned integer value of a datum.
484 */
485
486#define DatumGetUInt32(X) ((uint32) (X))
487
488/*
489 * UInt32GetDatum
490 * Returns datum representation for a 32-bit unsigned integer.
491 */
492
493#define UInt32GetDatum(X) ((Datum) (X))
494
495/*
496 * DatumGetObjectId
497 * Returns object identifier value of a datum.
498 */
499
500#define DatumGetObjectId(X) ((Oid) (X))
501
502/*
503 * ObjectIdGetDatum
504 * Returns datum representation for an object identifier.
505 */
506
507#define ObjectIdGetDatum(X) ((Datum) (X))
508
509/*
510 * DatumGetTransactionId
511 * Returns transaction identifier value of a datum.
512 */
513
514#define DatumGetTransactionId(X) ((TransactionId) (X))
515
516/*
517 * TransactionIdGetDatum
518 * Returns datum representation for a transaction identifier.
519 */
520
521#define TransactionIdGetDatum(X) ((Datum) (X))
522
523/*
524 * MultiXactIdGetDatum
525 * Returns datum representation for a multixact identifier.
526 */
527
528#define MultiXactIdGetDatum(X) ((Datum) (X))
529
530/*
531 * DatumGetCommandId
532 * Returns command identifier value of a datum.
533 */
534
535#define DatumGetCommandId(X) ((CommandId) (X))
536
537/*
538 * CommandIdGetDatum
539 * Returns datum representation for a command identifier.
540 */
541
542#define CommandIdGetDatum(X) ((Datum) (X))
543
544/*
545 * DatumGetPointer
546 * Returns pointer value of a datum.
547 */
548
549#define DatumGetPointer(X) ((Pointer) (X))
550
551/*
552 * PointerGetDatum
553 * Returns datum representation for a pointer.
554 */
555
556#define PointerGetDatum(X) ((Datum) (X))
557
558/*
559 * DatumGetCString
560 * Returns C string (null-terminated string) value of a datum.
561 *
562 * Note: C string is not a full-fledged Postgres type at present,
563 * but type input functions use this conversion for their inputs.
564 */
565
566#define DatumGetCString(X) ((char *) DatumGetPointer(X))
567
568/*
569 * CStringGetDatum
570 * Returns datum representation for a C string (null-terminated string).
571 *
572 * Note: C string is not a full-fledged Postgres type at present,
573 * but type output functions use this conversion for their outputs.
574 * Note: CString is pass-by-reference; caller must ensure the pointed-to
575 * value has adequate lifetime.
576 */
577
578#define CStringGetDatum(X) PointerGetDatum(X)
579
580/*
581 * DatumGetName
582 * Returns name value of a datum.
583 */
584
585#define DatumGetName(X) ((Name) DatumGetPointer(X))
586
587/*
588 * NameGetDatum
589 * Returns datum representation for a name.
590 *
591 * Note: Name is pass-by-reference; caller must ensure the pointed-to
592 * value has adequate lifetime.
593 */
594
595#define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
596
597/*
598 * DatumGetInt64
599 * Returns 64-bit integer value of a datum.
600 *
601 * Note: this macro hides whether int64 is pass by value or by reference.
602 */
603
604#ifdef USE_FLOAT8_BYVAL
605#define DatumGetInt64(X) ((int64) (X))
606#else
607#define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
608#endif
609
610/*
611 * Int64GetDatum
612 * Returns datum representation for a 64-bit integer.
613 *
614 * Note: if int64 is pass by reference, this function returns a reference
615 * to palloc'd space.
616 */
617
618#ifdef USE_FLOAT8_BYVAL
619#define Int64GetDatum(X) ((Datum) (X))
620#else
621extern Datum Int64GetDatum(int64 X);
622#endif
623
624/*
625 * DatumGetUInt64
626 * Returns 64-bit unsigned integer value of a datum.
627 *
628 * Note: this macro hides whether int64 is pass by value or by reference.
629 */
630
631#ifdef USE_FLOAT8_BYVAL
632#define DatumGetUInt64(X) ((uint64) (X))
633#else
634#define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
635#endif
636
637/*
638 * UInt64GetDatum
639 * Returns datum representation for a 64-bit unsigned integer.
640 *
641 * Note: if int64 is pass by reference, this function returns a reference
642 * to palloc'd space.
643 */
644
645#ifdef USE_FLOAT8_BYVAL
646#define UInt64GetDatum(X) ((Datum) (X))
647#else
648#define UInt64GetDatum(X) Int64GetDatum((int64) (X))
649#endif
650
651/*
652 * Float <-> Datum conversions
653 *
654 * These have to be implemented as inline functions rather than macros, when
655 * passing by value, because many machines pass int and float function
656 * parameters/results differently; so we need to play weird games with unions.
657 */
658
659/*
660 * DatumGetFloat4
661 * Returns 4-byte floating point value of a datum.
662 *
663 * Note: this macro hides whether float4 is pass by value or by reference.
664 */
665
666#ifdef USE_FLOAT4_BYVAL
667static inline float4
668DatumGetFloat4(Datum X)
669{
670 union
671 {
672 int32 value;
673 float4 retval;
674 } myunion;
675
676 myunion.value = DatumGetInt32(X);
677 return myunion.retval;
678}
679#else
680#define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
681#endif
682
683/*
684 * Float4GetDatum
685 * Returns datum representation for a 4-byte floating point number.
686 *
687 * Note: if float4 is pass by reference, this function returns a reference
688 * to palloc'd space.
689 */
690#ifdef USE_FLOAT4_BYVAL
691static inline Datum
692Float4GetDatum(float4 X)
693{
694 union
695 {
696 float4 value;
697 int32 retval;
698 } myunion;
699
700 myunion.value = X;
701 return Int32GetDatum(myunion.retval);
702}
703#else
704extern Datum Float4GetDatum(float4 X);
705#endif
706
707/*
708 * DatumGetFloat8
709 * Returns 8-byte floating point value of a datum.
710 *
711 * Note: this macro hides whether float8 is pass by value or by reference.
712 */
713
714#ifdef USE_FLOAT8_BYVAL
715static inline float8
716DatumGetFloat8(Datum X)
717{
718 union
719 {
720 int64 value;
721 float8 retval;
722 } myunion;
723
724 myunion.value = DatumGetInt64(X);
725 return myunion.retval;
726}
727#else
728#define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
729#endif
730
731/*
732 * Float8GetDatum
733 * Returns datum representation for an 8-byte floating point number.
734 *
735 * Note: if float8 is pass by reference, this function returns a reference
736 * to palloc'd space.
737 */
738
739#ifdef USE_FLOAT8_BYVAL
740static inline Datum
741Float8GetDatum(float8 X)
742{
743 union
744 {
745 float8 value;
746 int64 retval;
747 } myunion;
748
749 myunion.value = X;
750 return Int64GetDatum(myunion.retval);
751}
752#else
753extern Datum Float8GetDatum(float8 X);
754#endif
755
756
757/*
758 * Int64GetDatumFast
759 * Float8GetDatumFast
760 * Float4GetDatumFast
761 *
762 * These macros are intended to allow writing code that does not depend on
763 * whether int64, float8, float4 are pass-by-reference types, while not
764 * sacrificing performance when they are. The argument must be a variable
765 * that will exist and have the same value for as long as the Datum is needed.
766 * In the pass-by-ref case, the address of the variable is taken to use as
767 * the Datum. In the pass-by-val case, these will be the same as the non-Fast
768 * macros.
769 */
770
771#ifdef USE_FLOAT8_BYVAL
772#define Int64GetDatumFast(X) Int64GetDatum(X)
773#define Float8GetDatumFast(X) Float8GetDatum(X)
774#else
775#define Int64GetDatumFast(X) PointerGetDatum(&(X))
776#define Float8GetDatumFast(X) PointerGetDatum(&(X))
777#endif
778
779#ifdef USE_FLOAT4_BYVAL
780#define Float4GetDatumFast(X) Float4GetDatum(X)
781#else
782#define Float4GetDatumFast(X) PointerGetDatum(&(X))
783#endif
784
785#endif /* POSTGRES_H */
786