1 /*-------------------------------------------------------------------------
4 * Primary include file for PostgreSQL server .c files
6 * This should be the first file included by PostgreSQL backend modules.
7 * Client-side code should include postgres_fe.h instead.
10 * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1995, Regents of the University of California
13 * src/include/postgres.h
15 *-------------------------------------------------------------------------
18 *----------------------------------------------------------------
21 * When adding stuff to this file, please try to put stuff
22 * into the relevant section, or add new sections as appropriate.
25 * ------- ------------------------------------------------
26 * 1) variable-length datatypes (TOAST support)
27 * 2) datum type + support macros
28 * 3) exception handling backend support
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.
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.
42 *----------------------------------------------------------------
48 #include "utils/elog.h"
49 #include "utils/palloc.h"
51 /* ----------------------------------------------------------------
52 * Section 1: variable-length datatypes (TOAST support)
53 * ----------------------------------------------------------------
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.
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...)
68 typedef struct varatt_external
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 */
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.
82 * Note that just as for struct varatt_external, this struct is stored
83 * unaligned within any containing tuple.
85 typedef struct varatt_indirect
87 struct varlena *pointer; /* Pointer to in-memory varlena */
91 * Type tag for the various sorts of "TOAST pointer" datums. The peculiar
92 * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility
93 * with a previous notion that the tag field was the pointer datum's length.
95 typedef enum vartag_external
101 #define VARTAG_SIZE(tag) \
102 ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
103 (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
104 TrapMacro(true, "unrecognized TOAST vartag"))
107 * These structs describe the header of a varlena object that may have been
108 * TOASTed. Generally, don't reference these structs directly, but use the
111 * We use separate structs for the aligned and unaligned cases because the
112 * compiler might otherwise think it could generate code that assumes
113 * alignment while touching fields of a 1-byte-header varlena.
117 struct /* Normal varlena (4-byte length) */
120 char va_data[FLEXIBLE_ARRAY_MEMBER];
122 struct /* Compressed-in-line format */
125 uint32 va_rawsize; /* Original data size (excludes header) */
126 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
133 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */
136 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
139 uint8 va_header; /* Always 0x80 or 0x01 */
140 uint8 va_tag; /* Type of datum */
141 char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */
145 * Bit layouts for varlena headers on big-endian machines:
147 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
148 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
149 * 10000000 1-byte length word, unaligned, TOAST pointer
150 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
152 * Bit layouts for varlena headers on little-endian machines:
154 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
155 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
156 * 00000001 1-byte length word, unaligned, TOAST pointer
157 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
159 * The "xxx" bits are the length field (which includes itself in all cases).
160 * In the big-endian case we mask to extract the length, in the little-endian
161 * case we shift. Note that in both cases the flag bits are in the physically
162 * first byte. Also, it is not possible for a 1-byte length word to be zero;
163 * this lets us disambiguate alignment padding bytes from the start of an
164 * unaligned datum. (We now *require* pad bytes to be filled with zero!)
166 * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern
167 * the specific type and length of the pointer datum.
171 * Endian-dependent macros. These are considered internal --- use the
172 * external macros below instead of using these directly.
174 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
175 * for such records. Hence you should usually check for IS_EXTERNAL before
176 * checking for IS_1B.
179 #ifdef WORDS_BIGENDIAN
181 #define VARATT_IS_4B(PTR) \
182 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
183 #define VARATT_IS_4B_U(PTR) \
184 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
185 #define VARATT_IS_4B_C(PTR) \
186 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
187 #define VARATT_IS_1B(PTR) \
188 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
189 #define VARATT_IS_1B_E(PTR) \
190 ((((varattrib_1b *) (PTR))->va_header) == 0x80)
191 #define VARATT_NOT_PAD_BYTE(PTR) \
192 (*((uint8 *) (PTR)) != 0)
194 /* VARSIZE_4B() should only be used on known-aligned data */
195 #define VARSIZE_4B(PTR) \
196 (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
197 #define VARSIZE_1B(PTR) \
198 (((varattrib_1b *) (PTR))->va_header & 0x7F)
199 #define VARTAG_1B_E(PTR) \
200 (((varattrib_1b_e *) (PTR))->va_tag)
202 #define SET_VARSIZE_4B(PTR,len) \
203 (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
204 #define SET_VARSIZE_4B_C(PTR,len) \
205 (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
206 #define SET_VARSIZE_1B(PTR,len) \
207 (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
208 #define SET_VARTAG_1B_E(PTR,tag) \
209 (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
210 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
211 #else /* !WORDS_BIGENDIAN */
213 #define VARATT_IS_4B(PTR) \
214 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
215 #define VARATT_IS_4B_U(PTR) \
216 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
217 #define VARATT_IS_4B_C(PTR) \
218 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
219 #define VARATT_IS_1B(PTR) \
220 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
221 #define VARATT_IS_1B_E(PTR) \
222 ((((varattrib_1b *) (PTR))->va_header) == 0x01)
223 #define VARATT_NOT_PAD_BYTE(PTR) \
224 (*((uint8 *) (PTR)) != 0)
226 /* VARSIZE_4B() should only be used on known-aligned data */
227 #define VARSIZE_4B(PTR) \
228 ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
229 #define VARSIZE_1B(PTR) \
230 ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
231 #define VARTAG_1B_E(PTR) \
232 (((varattrib_1b_e *) (PTR))->va_tag)
234 #define SET_VARSIZE_4B(PTR,len) \
235 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
236 #define SET_VARSIZE_4B_C(PTR,len) \
237 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
238 #define SET_VARSIZE_1B(PTR,len) \
239 (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
240 #define SET_VARTAG_1B_E(PTR,tag) \
241 (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
242 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
243 #endif /* WORDS_BIGENDIAN */
245 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
246 #define VARATT_SHORT_MAX 0x7F
247 #define VARATT_CAN_MAKE_SHORT(PTR) \
248 (VARATT_IS_4B_U(PTR) && \
249 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
250 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
251 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
253 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
255 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
256 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
257 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
258 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
260 #define VARRAWSIZE_4B_C(PTR) \
261 (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
263 /* Externally visible macros */
266 * VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
267 * for varlena datatypes. Note that they only work on untoasted,
268 * 4-byte-header Datums!
270 * Code that wants to use 1-byte-header values without detoasting should
271 * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY. The other macros here
272 * should usually be used only by tuple assembly/disassembly code and
273 * code that specifically wants to work with still-toasted Datums.
275 * WARNING: It is only safe to use VARDATA_ANY() -- typically with
276 * PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
277 * Either because you're working with something like text where the alignment
278 * doesn't matter or because you're not going to access its constituent parts
279 * and just use things like memcpy on it anyways.
281 #define VARDATA(PTR) VARDATA_4B(PTR)
282 #define VARSIZE(PTR) VARSIZE_4B(PTR)
284 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
285 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
287 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
288 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
289 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
291 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
292 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
293 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
294 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
295 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
296 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
297 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
298 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
300 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
301 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
302 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
304 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
306 #define VARSIZE_ANY(PTR) \
307 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
308 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
311 /* Size of a varlena data, excluding header */
312 #define VARSIZE_ANY_EXHDR(PTR) \
313 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
314 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
315 VARSIZE_4B(PTR)-VARHDRSZ))
317 /* caution: this will not work on an external or compressed-in-line Datum */
318 /* caution: this will return a possibly unaligned pointer */
319 #define VARDATA_ANY(PTR) \
320 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
323 /* ----------------------------------------------------------------
324 * Section 2: datum type + support macros
325 * ----------------------------------------------------------------
330 * Postgres makes the following assumptions about datatype sizes:
332 * sizeof(Datum) == sizeof(void *) == 4 or 8
336 * When a type narrower than Datum is stored in a Datum, we place it in the
337 * low-order bits and are careful that the DatumGetXXX macro for it discards
338 * the unused high-order bits (as opposed to, say, assuming they are zero).
339 * This is needed to support old-style user-defined functions, since depending
340 * on architecture and compiler, the return value of a function returning char
341 * or short may contain garbage when called as if it returned Datum.
344 typedef uintptr_t Datum;
346 #define SIZEOF_DATUM SIZEOF_VOID_P
348 typedef Datum *DatumPtr;
350 #define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
351 #define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
352 #define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
353 #if SIZEOF_DATUM == 8
354 #define GET_8_BYTES(datum) ((Datum) (datum))
356 #define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
357 #define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
358 #define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)
359 #if SIZEOF_DATUM == 8
360 #define SET_8_BYTES(value) ((Datum) (value))
365 * Returns boolean value of a datum.
367 * Note: any nonzero value will be considered TRUE, but we ignore bits to
368 * the left of the width of bool, per comment above.
371 #define DatumGetBool(X) ((bool) (((bool) (X)) != 0))
375 * Returns datum representation for a boolean.
377 * Note: any nonzero value will be considered TRUE.
380 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
384 * Returns character value of a datum.
387 #define DatumGetChar(X) ((char) GET_1_BYTE(X))
391 * Returns datum representation for a character.
394 #define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
398 * Returns datum representation for an 8-bit integer.
401 #define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
405 * Returns 8-bit unsigned integer value of a datum.
408 #define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
412 * Returns datum representation for an 8-bit unsigned integer.
415 #define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
419 * Returns 16-bit integer value of a datum.
422 #define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
426 * Returns datum representation for a 16-bit integer.
429 #define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
433 * Returns 16-bit unsigned integer value of a datum.
436 #define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
440 * Returns datum representation for a 16-bit unsigned integer.
443 #define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
447 * Returns 32-bit integer value of a datum.
450 #define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
454 * Returns datum representation for a 32-bit integer.
457 #define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
461 * Returns 32-bit unsigned integer value of a datum.
464 #define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
468 * Returns datum representation for a 32-bit unsigned integer.
471 #define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
475 * Returns object identifier value of a datum.
478 #define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
482 * Returns datum representation for an object identifier.
485 #define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
488 * DatumGetTransactionId
489 * Returns transaction identifier value of a datum.
492 #define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
495 * TransactionIdGetDatum
496 * Returns datum representation for a transaction identifier.
499 #define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
502 * MultiXactIdGetDatum
503 * Returns datum representation for a multixact identifier.
506 #define MultiXactIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
510 * Returns command identifier value of a datum.
513 #define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
517 * Returns datum representation for a command identifier.
520 #define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
524 * Returns pointer value of a datum.
527 #define DatumGetPointer(X) ((Pointer) (X))
531 * Returns datum representation for a pointer.
534 #define PointerGetDatum(X) ((Datum) (X))
538 * Returns C string (null-terminated string) value of a datum.
540 * Note: C string is not a full-fledged Postgres type at present,
541 * but type input functions use this conversion for their inputs.
544 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
548 * Returns datum representation for a C string (null-terminated string).
550 * Note: C string is not a full-fledged Postgres type at present,
551 * but type output functions use this conversion for their outputs.
552 * Note: CString is pass-by-reference; caller must ensure the pointed-to
553 * value has adequate lifetime.
556 #define CStringGetDatum(X) PointerGetDatum(X)
560 * Returns name value of a datum.
563 #define DatumGetName(X) ((Name) DatumGetPointer(X))
567 * Returns datum representation for a name.
569 * Note: Name is pass-by-reference; caller must ensure the pointed-to
570 * value has adequate lifetime.
573 #define NameGetDatum(X) PointerGetDatum(X)
577 * Returns 64-bit integer value of a datum.
579 * Note: this macro hides whether int64 is pass by value or by reference.
582 #ifdef USE_FLOAT8_BYVAL
583 #define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
585 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
590 * Returns datum representation for a 64-bit integer.
592 * Note: if int64 is pass by reference, this function returns a reference
596 #ifdef USE_FLOAT8_BYVAL
597 #define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
599 extern Datum Int64GetDatum(int64 X);
604 * Returns 4-byte floating point value of a datum.
606 * Note: this macro hides whether float4 is pass by value or by reference.
609 #ifdef USE_FLOAT4_BYVAL
610 extern float4 DatumGetFloat4(Datum X);
612 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
617 * Returns datum representation for a 4-byte floating point number.
619 * Note: if float4 is pass by reference, this function returns a reference
623 extern Datum Float4GetDatum(float4 X);
627 * Returns 8-byte floating point value of a datum.
629 * Note: this macro hides whether float8 is pass by value or by reference.
632 #ifdef USE_FLOAT8_BYVAL
633 extern float8 DatumGetFloat8(Datum X);
635 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
640 * Returns datum representation for an 8-byte floating point number.
642 * Note: if float8 is pass by reference, this function returns a reference
646 extern Datum Float8GetDatum(float8 X);
654 * These macros are intended to allow writing code that does not depend on
655 * whether int64, float8, float4 are pass-by-reference types, while not
656 * sacrificing performance when they are. The argument must be a variable
657 * that will exist and have the same value for as long as the Datum is needed.
658 * In the pass-by-ref case, the address of the variable is taken to use as
659 * the Datum. In the pass-by-val case, these will be the same as the non-Fast
663 #ifdef USE_FLOAT8_BYVAL
664 #define Int64GetDatumFast(X) Int64GetDatum(X)
665 #define Float8GetDatumFast(X) Float8GetDatum(X)
667 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
668 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
671 #ifdef USE_FLOAT4_BYVAL
672 #define Float4GetDatumFast(X) Float4GetDatum(X)
674 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
678 /* ----------------------------------------------------------------
679 * Section 3: exception handling backend support
680 * ----------------------------------------------------------------
684 * Backend only infrastructure for the assertion-related macros in c.h.
686 * ExceptionalCondition must be present even when assertions are not enabled.
688 extern void ExceptionalCondition(const char *conditionName,
689 const char *errorType,
690 const char *fileName, int lineNumber) pg_attribute_noreturn();
692 #endif /* POSTGRES_H */