PostgreSQL Source Code  git master
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros
postgres.h
Go to the documentation of this file.
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) 1996-2017, 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  * 3) exception handling backend support
29  *
30  * NOTES
31  *
32  * In general, this file should contain declarations that are widely needed
33  * in the backend environment, but are of no interest outside the backend.
34  *
35  * Simple type definitions live in c.h, where they are shared with
36  * postgres_fe.h. We do that since those type definitions are needed by
37  * frontend modules that want to deal with binary data transmission to or
38  * from the backend. Type definitions in this file should be for
39  * representations that never escape the backend, such as Datum or
40  * TOASTed varlena objects.
41  *
42  *----------------------------------------------------------------
43  */
44 #ifndef POSTGRES_H
45 #define POSTGRES_H
46 
47 #include "c.h"
48 #include "utils/elog.h"
49 #include "utils/palloc.h"
50 
51 /* ----------------------------------------------------------------
52  * Section 1: variable-length datatypes (TOAST support)
53  * ----------------------------------------------------------------
54  */
55 
56 /*
57  * struct varatt_external is a traditional "TOAST pointer", that is, the
58  * information needed to fetch a Datum stored out-of-line in a TOAST table.
59  * The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ.
60  * This struct must not contain any padding, because we sometimes compare
61  * these pointers using memcmp.
62  *
63  * Note that this information is stored unaligned within actual tuples, so
64  * you need to memcpy from the tuple into a local struct variable before
65  * you can look at these fields! (The reason we use memcmp is to avoid
66  * having to do that just to detect equality of two TOAST pointers...)
67  */
68 typedef struct varatt_external
69 {
70  int32 va_rawsize; /* Original data size (includes header) */
71  int32 va_extsize; /* External saved size (doesn't) */
72  Oid va_valueid; /* Unique ID of value within TOAST table */
73  Oid va_toastrelid; /* RelID of TOAST table containing it */
75 
76 /*
77  * struct varatt_indirect is a "TOAST pointer" representing an out-of-line
78  * Datum that's stored in memory, not in an external toast relation.
79  * The creator of such a Datum is entirely responsible that the referenced
80  * storage survives for as long as referencing pointer Datums can exist.
81  *
82  * Note that just as for struct varatt_external, this struct is stored
83  * unaligned within any containing tuple.
84  */
85 typedef struct varatt_indirect
86 {
87  struct varlena *pointer; /* Pointer to in-memory varlena */
89 
90 /*
91  * struct varatt_expanded is a "TOAST pointer" representing an out-of-line
92  * Datum that is stored in memory, in some type-specific, not necessarily
93  * physically contiguous format that is convenient for computation not
94  * storage. APIs for this, in particular the definition of struct
95  * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.
96  *
97  * Note that just as for struct varatt_external, this struct is stored
98  * unaligned within any containing tuple.
99  */
101 
102 typedef struct varatt_expanded
103 {
106 
107 /*
108  * Type tag for the various sorts of "TOAST pointer" datums. The peculiar
109  * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
110  * with a previous notion that the tag field was the pointer datum's length.
111  */
112 typedef enum vartag_external
113 {
119 
120 /* this test relies on the specific tag values above */
121 #define VARTAG_IS_EXPANDED(tag) \
122  (((tag) & ~1) == VARTAG_EXPANDED_RO)
123 
124 #define VARTAG_SIZE(tag) \
125  ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
126  VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \
127  (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
128  TrapMacro(true, "unrecognized TOAST vartag"))
129 
130 /*
131  * These structs describe the header of a varlena object that may have been
132  * TOASTed. Generally, don't reference these structs directly, but use the
133  * macros below.
134  *
135  * We use separate structs for the aligned and unaligned cases because the
136  * compiler might otherwise think it could generate code that assumes
137  * alignment while touching fields of a 1-byte-header varlena.
138  */
139 typedef union
140 {
141  struct /* Normal varlena (4-byte length) */
142  {
144  char va_data[FLEXIBLE_ARRAY_MEMBER];
145  } va_4byte;
146  struct /* Compressed-in-line format */
147  {
148  uint32 va_header;
149  uint32 va_rawsize; /* Original data size (excludes header) */
150  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
151  } va_compressed;
152 } varattrib_4b;
153 
154 typedef struct
155 {
157  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
158 } varattrib_1b;
159 
160 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
161 typedef struct
162 {
163  uint8 va_header; /* Always 0x80 or 0x01 */
164  uint8 va_tag; /* Type of datum */
165  char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
167 
168 /*
169  * Bit layouts for varlena headers on big-endian machines:
170  *
171  * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
172  * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
173  * 10000000 1-byte length word, unaligned, TOAST pointer
174  * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
175  *
176  * Bit layouts for varlena headers on little-endian machines:
177  *
178  * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
179  * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
180  * 00000001 1-byte length word, unaligned, TOAST pointer
181  * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
182  *
183  * The "xxx" bits are the length field (which includes itself in all cases).
184  * In the big-endian case we mask to extract the length, in the little-endian
185  * case we shift. Note that in both cases the flag bits are in the physically
186  * first byte. Also, it is not possible for a 1-byte length word to be zero;
187  * this lets us disambiguate alignment padding bytes from the start of an
188  * unaligned datum. (We now *require* pad bytes to be filled with zero!)
189  *
190  * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
191  * the specific type and length of the pointer datum.
192  */
193 
194 /*
195  * Endian-dependent macros. These are considered internal --- use the
196  * external macros below instead of using these directly.
197  *
198  * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
199  * for such records. Hence you should usually check for IS_EXTERNAL before
200  * checking for IS_1B.
201  */
202 
203 #ifdef WORDS_BIGENDIAN
204 
205 #define VARATT_IS_4B(PTR) \
206  ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
207 #define VARATT_IS_4B_U(PTR) \
208  ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
209 #define VARATT_IS_4B_C(PTR) \
210  ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
211 #define VARATT_IS_1B(PTR) \
212  ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
213 #define VARATT_IS_1B_E(PTR) \
214  ((((varattrib_1b *) (PTR))->va_header) == 0x80)
215 #define VARATT_NOT_PAD_BYTE(PTR) \
216  (*((uint8 *) (PTR)) != 0)
217 
218 /* VARSIZE_4B() should only be used on known-aligned data */
219 #define VARSIZE_4B(PTR) \
220  (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
221 #define VARSIZE_1B(PTR) \
222  (((varattrib_1b *) (PTR))->va_header & 0x7F)
223 #define VARTAG_1B_E(PTR) \
224  (((varattrib_1b_e *) (PTR))->va_tag)
225 
226 #define SET_VARSIZE_4B(PTR,len) \
227  (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
228 #define SET_VARSIZE_4B_C(PTR,len) \
229  (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
230 #define SET_VARSIZE_1B(PTR,len) \
231  (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
232 #define SET_VARTAG_1B_E(PTR,tag) \
233  (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
234  ((varattrib_1b_e *) (PTR))->va_tag = (tag))
235 #else /* !WORDS_BIGENDIAN */
236 
237 #define VARATT_IS_4B(PTR) \
238  ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
239 #define VARATT_IS_4B_U(PTR) \
240  ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
241 #define VARATT_IS_4B_C(PTR) \
242  ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
243 #define VARATT_IS_1B(PTR) \
244  ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
245 #define VARATT_IS_1B_E(PTR) \
246  ((((varattrib_1b *) (PTR))->va_header) == 0x01)
247 #define VARATT_NOT_PAD_BYTE(PTR) \
248  (*((uint8 *) (PTR)) != 0)
249 
250 /* VARSIZE_4B() should only be used on known-aligned data */
251 #define VARSIZE_4B(PTR) \
252  ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
253 #define VARSIZE_1B(PTR) \
254  ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
255 #define VARTAG_1B_E(PTR) \
256  (((varattrib_1b_e *) (PTR))->va_tag)
257 
258 #define SET_VARSIZE_4B(PTR,len) \
259  (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
260 #define SET_VARSIZE_4B_C(PTR,len) \
261  (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
262 #define SET_VARSIZE_1B(PTR,len) \
263  (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
264 #define SET_VARTAG_1B_E(PTR,tag) \
265  (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
266  ((varattrib_1b_e *) (PTR))->va_tag = (tag))
267 #endif /* WORDS_BIGENDIAN */
268 
269 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
270 #define VARATT_SHORT_MAX 0x7F
271 #define VARATT_CAN_MAKE_SHORT(PTR) \
272  (VARATT_IS_4B_U(PTR) && \
273  (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
274 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
275  (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
276 
277 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
278 
279 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
280 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
281 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
282 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
283 
284 #define VARRAWSIZE_4B_C(PTR) \
285  (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
286 
287 /* Externally visible macros */
288 
289 /*
290  * VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
291  * for varlena datatypes. Note that they only work on untoasted,
292  * 4-byte-header Datums!
293  *
294  * Code that wants to use 1-byte-header values without detoasting should
295  * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY. The other macros here
296  * should usually be used only by tuple assembly/disassembly code and
297  * code that specifically wants to work with still-toasted Datums.
298  *
299  * WARNING: It is only safe to use VARDATA_ANY() -- typically with
300  * PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
301  * Either because you're working with something like text where the alignment
302  * doesn't matter or because you're not going to access its constituent parts
303  * and just use things like memcpy on it anyways.
304  */
305 #define VARDATA(PTR) VARDATA_4B(PTR)
306 #define VARSIZE(PTR) VARSIZE_4B(PTR)
307 
308 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
309 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
310 
311 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
312 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
313 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
314 
315 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
316 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
317 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
318  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
319 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
320  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
321 #define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \
322  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)
323 #define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \
324  (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)
325 #define VARATT_IS_EXTERNAL_EXPANDED(PTR) \
326  (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
327 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
328 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
329 
330 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
331 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
332 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
333 
334 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
335 
336 #define VARSIZE_ANY(PTR) \
337  (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
338  (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
339  VARSIZE_4B(PTR)))
340 
341 /* Size of a varlena data, excluding header */
342 #define VARSIZE_ANY_EXHDR(PTR) \
343  (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
344  (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
345  VARSIZE_4B(PTR)-VARHDRSZ))
346 
347 /* caution: this will not work on an external or compressed-in-line Datum */
348 /* caution: this will return a possibly unaligned pointer */
349 #define VARDATA_ANY(PTR) \
350  (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
351 
352 
353 /* ----------------------------------------------------------------
354  * Section 2: datum type + support macros
355  * ----------------------------------------------------------------
356  */
357 
358 /*
359  * Port Notes:
360  * Postgres makes the following assumptions about datatype sizes:
361  *
362  * sizeof(Datum) == sizeof(void *) == 4 or 8
363  * sizeof(char) == 1
364  * sizeof(short) == 2
365  *
366  * When a type narrower than Datum is stored in a Datum, we place it in the
367  * low-order bits and are careful that the DatumGetXXX macro for it discards
368  * the unused high-order bits (as opposed to, say, assuming they are zero).
369  * This is needed to support old-style user-defined functions, since depending
370  * on architecture and compiler, the return value of a function returning char
371  * or short may contain garbage when called as if it returned Datum.
372  */
373 
374 typedef uintptr_t Datum;
375 
376 #define SIZEOF_DATUM SIZEOF_VOID_P
377 
378 typedef Datum *DatumPtr;
379 
380 #define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
381 #define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
382 #define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
383 #if SIZEOF_DATUM == 8
384 #define GET_8_BYTES(datum) ((Datum) (datum))
385 #endif
386 #define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
387 #define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
388 #define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)
389 #if SIZEOF_DATUM == 8
390 #define SET_8_BYTES(value) ((Datum) (value))
391 #endif
392 
393 /*
394  * DatumGetBool
395  * Returns boolean value of a datum.
396  *
397  * Note: any nonzero value will be considered TRUE, but we ignore bits to
398  * the left of the width of bool, per comment above.
399  */
400 
401 #define DatumGetBool(X) ((bool) (GET_1_BYTE(X) != 0))
402 
403 /*
404  * BoolGetDatum
405  * Returns datum representation for a boolean.
406  *
407  * Note: any nonzero value will be considered TRUE.
408  */
409 
410 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
411 
412 /*
413  * DatumGetChar
414  * Returns character value of a datum.
415  */
416 
417 #define DatumGetChar(X) ((char) GET_1_BYTE(X))
418 
419 /*
420  * CharGetDatum
421  * Returns datum representation for a character.
422  */
423 
424 #define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
425 
426 /*
427  * Int8GetDatum
428  * Returns datum representation for an 8-bit integer.
429  */
430 
431 #define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
432 
433 /*
434  * DatumGetUInt8
435  * Returns 8-bit unsigned integer value of a datum.
436  */
437 
438 #define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
439 
440 /*
441  * UInt8GetDatum
442  * Returns datum representation for an 8-bit unsigned integer.
443  */
444 
445 #define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
446 
447 /*
448  * DatumGetInt16
449  * Returns 16-bit integer value of a datum.
450  */
451 
452 #define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
453 
454 /*
455  * Int16GetDatum
456  * Returns datum representation for a 16-bit integer.
457  */
458 
459 #define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
460 
461 /*
462  * DatumGetUInt16
463  * Returns 16-bit unsigned integer value of a datum.
464  */
465 
466 #define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
467 
468 /*
469  * UInt16GetDatum
470  * Returns datum representation for a 16-bit unsigned integer.
471  */
472 
473 #define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
474 
475 /*
476  * DatumGetInt32
477  * Returns 32-bit integer value of a datum.
478  */
479 
480 #define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
481 
482 /*
483  * Int32GetDatum
484  * Returns datum representation for a 32-bit integer.
485  */
486 
487 #define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
488 
489 /*
490  * DatumGetUInt32
491  * Returns 32-bit unsigned integer value of a datum.
492  */
493 
494 #define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
495 
496 /*
497  * UInt32GetDatum
498  * Returns datum representation for a 32-bit unsigned integer.
499  */
500 
501 #define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
502 
503 /*
504  * DatumGetObjectId
505  * Returns object identifier value of a datum.
506  */
507 
508 #define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
509 
510 /*
511  * ObjectIdGetDatum
512  * Returns datum representation for an object identifier.
513  */
514 
515 #define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
516 
517 /*
518  * DatumGetTransactionId
519  * Returns transaction identifier value of a datum.
520  */
521 
522 #define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
523 
524 /*
525  * TransactionIdGetDatum
526  * Returns datum representation for a transaction identifier.
527  */
528 
529 #define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
530 
531 /*
532  * MultiXactIdGetDatum
533  * Returns datum representation for a multixact identifier.
534  */
535 
536 #define MultiXactIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
537 
538 /*
539  * DatumGetCommandId
540  * Returns command identifier value of a datum.
541  */
542 
543 #define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
544 
545 /*
546  * CommandIdGetDatum
547  * Returns datum representation for a command identifier.
548  */
549 
550 #define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
551 
552 /*
553  * DatumGetPointer
554  * Returns pointer value of a datum.
555  */
556 
557 #define DatumGetPointer(X) ((Pointer) (X))
558 
559 /*
560  * PointerGetDatum
561  * Returns datum representation for a pointer.
562  */
563 
564 #define PointerGetDatum(X) ((Datum) (X))
565 
566 /*
567  * DatumGetCString
568  * Returns C string (null-terminated string) value of a datum.
569  *
570  * Note: C string is not a full-fledged Postgres type at present,
571  * but type input functions use this conversion for their inputs.
572  */
573 
574 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
575 
576 /*
577  * CStringGetDatum
578  * Returns datum representation for a C string (null-terminated string).
579  *
580  * Note: C string is not a full-fledged Postgres type at present,
581  * but type output functions use this conversion for their outputs.
582  * Note: CString is pass-by-reference; caller must ensure the pointed-to
583  * value has adequate lifetime.
584  */
585 
586 #define CStringGetDatum(X) PointerGetDatum(X)
587 
588 /*
589  * DatumGetName
590  * Returns name value of a datum.
591  */
592 
593 #define DatumGetName(X) ((Name) DatumGetPointer(X))
594 
595 /*
596  * NameGetDatum
597  * Returns datum representation for a name.
598  *
599  * Note: Name is pass-by-reference; caller must ensure the pointed-to
600  * value has adequate lifetime.
601  */
602 
603 #define NameGetDatum(X) CStringGetDatum(NameStr(*(X)))
604 
605 /*
606  * DatumGetInt64
607  * Returns 64-bit integer value of a datum.
608  *
609  * Note: this macro hides whether int64 is pass by value or by reference.
610  */
611 
612 #ifdef USE_FLOAT8_BYVAL
613 #define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
614 #else
615 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
616 #endif
617 
618 /*
619  * Int64GetDatum
620  * Returns datum representation for a 64-bit integer.
621  *
622  * Note: if int64 is pass by reference, this function returns a reference
623  * to palloc'd space.
624  */
625 
626 #ifdef USE_FLOAT8_BYVAL
627 #define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
628 #else
629 extern Datum Int64GetDatum(int64 X);
630 #endif
631 
632 /*
633  * DatumGetUInt64
634  * Returns 64-bit unsigned integer value of a datum.
635  *
636  * Note: this macro hides whether int64 is pass by value or by reference.
637  */
638 
639 #ifdef USE_FLOAT8_BYVAL
640 #define DatumGetUInt64(X) ((uint64) GET_8_BYTES(X))
641 #else
642 #define DatumGetUInt64(X) (* ((uint64 *) DatumGetPointer(X)))
643 #endif
644 
645 /*
646  * UInt64GetDatum
647  * Returns datum representation for a 64-bit unsigned integer.
648  *
649  * Note: if int64 is pass by reference, this function returns a reference
650  * to palloc'd space.
651  */
652 
653 #ifdef USE_FLOAT8_BYVAL
654 #define UInt64GetDatum(X) ((Datum) SET_8_BYTES(X))
655 #else
656 #define UInt64GetDatum(X) Int64GetDatum((int64) (X))
657 #endif
658 
659 /*
660  * Float <-> Datum conversions
661  *
662  * These have to be implemented as inline functions rather than macros, when
663  * passing by value, because many machines pass int and float function
664  * parameters/results differently; so we need to play weird games with unions.
665  */
666 
667 /*
668  * DatumGetFloat4
669  * Returns 4-byte floating point value of a datum.
670  *
671  * Note: this macro hides whether float4 is pass by value or by reference.
672  */
673 
674 #ifdef USE_FLOAT4_BYVAL
675 static inline float4
677 {
678  union
679  {
680  int32 value;
681  float4 retval;
682  } myunion;
683 
684  myunion.value = GET_4_BYTES(X);
685  return myunion.retval;
686 }
687 #else
688 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
689 #endif
690 
691 /*
692  * Float4GetDatum
693  * Returns datum representation for a 4-byte floating point number.
694  *
695  * Note: if float4 is pass by reference, this function returns a reference
696  * to palloc'd space.
697  */
698 #ifdef USE_FLOAT4_BYVAL
699 static inline Datum
701 {
702  union
703  {
704  float4 value;
705  int32 retval;
706  } myunion;
707 
708  myunion.value = X;
709  return SET_4_BYTES(myunion.retval);
710 }
711 #else
712 extern Datum Float4GetDatum(float4 X);
713 #endif
714 
715 /*
716  * DatumGetFloat8
717  * Returns 8-byte floating point value of a datum.
718  *
719  * Note: this macro hides whether float8 is pass by value or by reference.
720  */
721 
722 #ifdef USE_FLOAT8_BYVAL
723 static inline float8
725 {
726  union
727  {
728  int64 value;
729  float8 retval;
730  } myunion;
731 
732  myunion.value = GET_8_BYTES(X);
733  return myunion.retval;
734 }
735 #else
736 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
737 #endif
738 
739 /*
740  * Float8GetDatum
741  * Returns datum representation for an 8-byte floating point number.
742  *
743  * Note: if float8 is pass by reference, this function returns a reference
744  * to palloc'd space.
745  */
746 
747 #ifdef USE_FLOAT8_BYVAL
748 static inline Datum
750 {
751  union
752  {
753  float8 value;
754  int64 retval;
755  } myunion;
756 
757  myunion.value = X;
758  return SET_8_BYTES(myunion.retval);
759 }
760 #else
761 extern Datum Float8GetDatum(float8 X);
762 #endif
763 
764 
765 /*
766  * Int64GetDatumFast
767  * Float8GetDatumFast
768  * Float4GetDatumFast
769  *
770  * These macros are intended to allow writing code that does not depend on
771  * whether int64, float8, float4 are pass-by-reference types, while not
772  * sacrificing performance when they are. The argument must be a variable
773  * that will exist and have the same value for as long as the Datum is needed.
774  * In the pass-by-ref case, the address of the variable is taken to use as
775  * the Datum. In the pass-by-val case, these will be the same as the non-Fast
776  * macros.
777  */
778 
779 #ifdef USE_FLOAT8_BYVAL
780 #define Int64GetDatumFast(X) Int64GetDatum(X)
781 #define Float8GetDatumFast(X) Float8GetDatum(X)
782 #else
783 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
784 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
785 #endif
786 
787 #ifdef USE_FLOAT4_BYVAL
788 #define Float4GetDatumFast(X) Float4GetDatum(X)
789 #else
790 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
791 #endif
792 
793 
794 /* ----------------------------------------------------------------
795  * Section 3: exception handling backend support
796  * ----------------------------------------------------------------
797  */
798 
799 /*
800  * Backend only infrastructure for the assertion-related macros in c.h.
801  *
802  * ExceptionalCondition must be present even when assertions are not enabled.
803  */
804 extern void ExceptionalCondition(const char *conditionName,
805  const char *errorType,
806  const char *fileName, int lineNumber) pg_attribute_noreturn();
807 
808 #endif /* POSTGRES_H */
vartag_external
Definition: postgres.h:112
ExpandedObjectHeader * eohptr
Definition: postgres.h:104
static struct @76 value
Datum Float4GetDatum(float4 X)
Definition: fmgr.c:2114
struct varatt_expanded varatt_expanded
uint8 va_tag
Definition: postgres.h:164
unsigned char uint8
Definition: c.h:263
Oid va_toastrelid
Definition: postgres.h:73
int32 va_rawsize
Definition: postgres.h:70
#define pg_attribute_noreturn()
Definition: c.h:649
unsigned int Oid
Definition: postgres_ext.h:31
signed int int32
Definition: c.h:253
#define GET_4_BYTES(datum)
Definition: postgres.h:382
double float8
Definition: c.h:378
Datum Float8GetDatum(float8 X)
Definition: fmgr.c:2126
unsigned int uint32
Definition: c.h:265
uint8 va_header
Definition: postgres.h:156
Datum * DatumPtr
Definition: postgres.h:378
float float4
Definition: c.h:377
uint8 va_header
Definition: postgres.h:163
#define DatumGetFloat8(X)
Definition: postgres.h:736
uintptr_t Datum
Definition: postgres.h:374
void ExceptionalCondition(const char *conditionName, const char *errorType, const char *fileName, int lineNumber) pg_attribute_noreturn()
Definition: assert.c:26
int32 va_extsize
Definition: postgres.h:71
#define DatumGetFloat4(X)
Definition: postgres.h:688
uint32 va_header
Definition: postgres.h:143
struct varlena * pointer
Definition: postgres.h:87
struct varatt_external varatt_external
#define SET_4_BYTES(value)
Definition: postgres.h:388
uint32 va_rawsize
Definition: postgres.h:149
Datum Int64GetDatum(int64 X)
Definition: fmgr.c:2102
Definition: c.h:435
struct varatt_indirect varatt_indirect