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) 1996-2014, 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 "TOAST pointer", that is, the information needed
58 * to fetch a Datum stored in an out-of-line on-disk Datum. The data is
59 * compressed if and only if va_extsize < va_rawsize - VARHDRSZ. This struct
60 * must not contain any padding, because we sometimes compare pointers using
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 * Out-of-line Datum thats stored in memory in contrast to varatt_external
78 * pointers which points to data in an external toast relation.
80 * Note that just as varatt_external's this is stored unaligned within the
83 typedef struct varatt_indirect
85 struct varlena *pointer; /* Pointer to in-memory varlena */
90 * Type of external toast datum stored. The peculiar value for VARTAG_ONDISK
91 * comes from the requirement for on-disk compatibility with the older
92 * definitions of varattrib_1b_e where v_tag was named va_len_1be...
94 typedef enum vartag_external
100 #define VARTAG_SIZE(tag) \
101 ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
102 (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
103 TrapMacro(true, "unknown vartag"))
106 * These structs describe the header of a varlena object that may have been
107 * TOASTed. Generally, don't reference these structs directly, but use the
110 * We use separate structs for the aligned and unaligned cases because the
111 * compiler might otherwise think it could generate code that assumes
112 * alignment while touching fields of a 1-byte-header varlena.
116 struct /* Normal varlena (4-byte length) */
121 struct /* Compressed-in-line format */
124 uint32 va_rawsize; /* Original data size (excludes header) */
125 char va_data[1]; /* Compressed data */
132 char va_data[1]; /* Data begins here */
135 /* inline portion of a short varlena pointing to an external resource */
138 uint8 va_header; /* Always 0x80 or 0x01 */
139 uint8 va_tag; /* Type of datum */
140 char va_data[1]; /* Data (of the type indicated by va_tag) */
144 * Bit layouts for varlena headers on big-endian machines:
146 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
147 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
148 * 10000000 1-byte length word, unaligned, TOAST pointer
149 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
151 * Bit layouts for varlena headers on little-endian machines:
153 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
154 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
155 * 00000001 1-byte length word, unaligned, TOAST pointer
156 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
158 * The "xxx" bits are the length field (which includes itself in all cases).
159 * In the big-endian case we mask to extract the length, in the little-endian
160 * case we shift. Note that in both cases the flag bits are in the physically
161 * first byte. Also, it is not possible for a 1-byte length word to be zero;
162 * this lets us disambiguate alignment padding bytes from the start of an
163 * unaligned datum. (We now *require* pad bytes to be filled with zero!)
165 * In TOAST datums the tag field in varattrib_1b_e is used to discern whether
166 * its an indirection pointer or more commonly an on-disk tuple.
170 * Endian-dependent macros. These are considered internal --- use the
171 * external macros below instead of using these directly.
173 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
174 * for such records. Hence you should usually check for IS_EXTERNAL before
175 * checking for IS_1B.
178 #ifdef WORDS_BIGENDIAN
180 #define VARATT_IS_4B(PTR) \
181 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
182 #define VARATT_IS_4B_U(PTR) \
183 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
184 #define VARATT_IS_4B_C(PTR) \
185 ((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
186 #define VARATT_IS_1B(PTR) \
187 ((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
188 #define VARATT_IS_1B_E(PTR) \
189 ((((varattrib_1b *) (PTR))->va_header) == 0x80)
190 #define VARATT_NOT_PAD_BYTE(PTR) \
191 (*((uint8 *) (PTR)) != 0)
193 /* VARSIZE_4B() should only be used on known-aligned data */
194 #define VARSIZE_4B(PTR) \
195 (((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
196 #define VARSIZE_1B(PTR) \
197 (((varattrib_1b *) (PTR))->va_header & 0x7F)
198 #define VARTAG_1B_E(PTR) \
199 (((varattrib_1b_e *) (PTR))->va_tag)
201 #define SET_VARSIZE_4B(PTR,len) \
202 (((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
203 #define SET_VARSIZE_4B_C(PTR,len) \
204 (((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
205 #define SET_VARSIZE_1B(PTR,len) \
206 (((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
207 #define SET_VARTAG_1B_E(PTR,tag) \
208 (((varattrib_1b_e *) (PTR))->va_header = 0x80, \
209 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
210 #else /* !WORDS_BIGENDIAN */
212 #define VARATT_IS_4B(PTR) \
213 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
214 #define VARATT_IS_4B_U(PTR) \
215 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
216 #define VARATT_IS_4B_C(PTR) \
217 ((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
218 #define VARATT_IS_1B(PTR) \
219 ((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
220 #define VARATT_IS_1B_E(PTR) \
221 ((((varattrib_1b *) (PTR))->va_header) == 0x01)
222 #define VARATT_NOT_PAD_BYTE(PTR) \
223 (*((uint8 *) (PTR)) != 0)
225 /* VARSIZE_4B() should only be used on known-aligned data */
226 #define VARSIZE_4B(PTR) \
227 ((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
228 #define VARSIZE_1B(PTR) \
229 ((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
230 #define VARTAG_1B_E(PTR) \
231 (((varattrib_1b_e *) (PTR))->va_tag)
233 #define SET_VARSIZE_4B(PTR,len) \
234 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
235 #define SET_VARSIZE_4B_C(PTR,len) \
236 (((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
237 #define SET_VARSIZE_1B(PTR,len) \
238 (((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
239 #define SET_VARTAG_1B_E(PTR,tag) \
240 (((varattrib_1b_e *) (PTR))->va_header = 0x01, \
241 ((varattrib_1b_e *) (PTR))->va_tag = (tag))
242 #endif /* WORDS_BIGENDIAN */
244 #define VARHDRSZ_SHORT offsetof(varattrib_1b, va_data)
245 #define VARATT_SHORT_MAX 0x7F
246 #define VARATT_CAN_MAKE_SHORT(PTR) \
247 (VARATT_IS_4B_U(PTR) && \
248 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
249 #define VARATT_CONVERTED_SHORT_SIZE(PTR) \
250 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
252 #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data)
254 #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data)
255 #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data)
256 #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data)
257 #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data)
259 #define VARRAWSIZE_4B_C(PTR) \
260 (((varattrib_4b *) (PTR))->va_compressed.va_rawsize)
262 /* Externally visible macros */
265 * VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
266 * for varlena datatypes. Note that they only work on untoasted,
267 * 4-byte-header Datums!
269 * Code that wants to use 1-byte-header values without detoasting should
270 * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY. The other macros here
271 * should usually be used only by tuple assembly/disassembly code and
272 * code that specifically wants to work with still-toasted Datums.
274 * WARNING: It is only safe to use VARDATA_ANY() -- typically with
275 * PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
276 * Either because you're working with something like text where the alignment
277 * doesn't matter or because you're not going to access its constituent parts
278 * and just use things like memcpy on it anyways.
280 #define VARDATA(PTR) VARDATA_4B(PTR)
281 #define VARSIZE(PTR) VARSIZE_4B(PTR)
283 #define VARSIZE_SHORT(PTR) VARSIZE_1B(PTR)
284 #define VARDATA_SHORT(PTR) VARDATA_1B(PTR)
286 #define VARTAG_EXTERNAL(PTR) VARTAG_1B_E(PTR)
287 #define VARSIZE_EXTERNAL(PTR) (VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))
288 #define VARDATA_EXTERNAL(PTR) VARDATA_1B_E(PTR)
290 #define VARATT_IS_COMPRESSED(PTR) VARATT_IS_4B_C(PTR)
291 #define VARATT_IS_EXTERNAL(PTR) VARATT_IS_1B_E(PTR)
292 #define VARATT_IS_EXTERNAL_ONDISK(PTR) \
293 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)
294 #define VARATT_IS_EXTERNAL_INDIRECT(PTR) \
295 (VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)
296 #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR)
297 #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR))
299 #define SET_VARSIZE(PTR, len) SET_VARSIZE_4B(PTR, len)
300 #define SET_VARSIZE_SHORT(PTR, len) SET_VARSIZE_1B(PTR, len)
301 #define SET_VARSIZE_COMPRESSED(PTR, len) SET_VARSIZE_4B_C(PTR, len)
303 #define SET_VARTAG_EXTERNAL(PTR, tag) SET_VARTAG_1B_E(PTR, tag)
305 #define VARSIZE_ANY(PTR) \
306 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \
307 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
310 /* Size of a varlena data, excluding header */
311 #define VARSIZE_ANY_EXHDR(PTR) \
312 (VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \
313 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
314 VARSIZE_4B(PTR)-VARHDRSZ))
316 /* caution: this will not work on an external or compressed-in-line Datum */
317 /* caution: this will return a possibly unaligned pointer */
318 #define VARDATA_ANY(PTR) \
319 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
322 /* ----------------------------------------------------------------
323 * Section 2: datum type + support macros
324 * ----------------------------------------------------------------
329 * Postgres makes the following assumptions about datatype sizes:
331 * sizeof(Datum) == sizeof(void *) == 4 or 8
335 * When a type narrower than Datum is stored in a Datum, we place it in the
336 * low-order bits and are careful that the DatumGetXXX macro for it discards
337 * the unused high-order bits (as opposed to, say, assuming they are zero).
338 * This is needed to support old-style user-defined functions, since depending
339 * on architecture and compiler, the return value of a function returning char
340 * or short may contain garbage when called as if it returned Datum.
343 typedef uintptr_t Datum;
345 #define SIZEOF_DATUM SIZEOF_VOID_P
347 typedef Datum *DatumPtr;
349 #define GET_1_BYTE(datum) (((Datum) (datum)) & 0x000000ff)
350 #define GET_2_BYTES(datum) (((Datum) (datum)) & 0x0000ffff)
351 #define GET_4_BYTES(datum) (((Datum) (datum)) & 0xffffffff)
352 #if SIZEOF_DATUM == 8
353 #define GET_8_BYTES(datum) ((Datum) (datum))
355 #define SET_1_BYTE(value) (((Datum) (value)) & 0x000000ff)
356 #define SET_2_BYTES(value) (((Datum) (value)) & 0x0000ffff)
357 #define SET_4_BYTES(value) (((Datum) (value)) & 0xffffffff)
358 #if SIZEOF_DATUM == 8
359 #define SET_8_BYTES(value) ((Datum) (value))
364 * Returns boolean value of a datum.
366 * Note: any nonzero value will be considered TRUE, but we ignore bits to
367 * the left of the width of bool, per comment above.
370 #define DatumGetBool(X) ((bool) (((bool) (X)) != 0))
374 * Returns datum representation for a boolean.
376 * Note: any nonzero value will be considered TRUE.
379 #define BoolGetDatum(X) ((Datum) ((X) ? 1 : 0))
383 * Returns character value of a datum.
386 #define DatumGetChar(X) ((char) GET_1_BYTE(X))
390 * Returns datum representation for a character.
393 #define CharGetDatum(X) ((Datum) SET_1_BYTE(X))
397 * Returns datum representation for an 8-bit integer.
400 #define Int8GetDatum(X) ((Datum) SET_1_BYTE(X))
404 * Returns 8-bit unsigned integer value of a datum.
407 #define DatumGetUInt8(X) ((uint8) GET_1_BYTE(X))
411 * Returns datum representation for an 8-bit unsigned integer.
414 #define UInt8GetDatum(X) ((Datum) SET_1_BYTE(X))
418 * Returns 16-bit integer value of a datum.
421 #define DatumGetInt16(X) ((int16) GET_2_BYTES(X))
425 * Returns datum representation for a 16-bit integer.
428 #define Int16GetDatum(X) ((Datum) SET_2_BYTES(X))
432 * Returns 16-bit unsigned integer value of a datum.
435 #define DatumGetUInt16(X) ((uint16) GET_2_BYTES(X))
439 * Returns datum representation for a 16-bit unsigned integer.
442 #define UInt16GetDatum(X) ((Datum) SET_2_BYTES(X))
446 * Returns 32-bit integer value of a datum.
449 #define DatumGetInt32(X) ((int32) GET_4_BYTES(X))
453 * Returns datum representation for a 32-bit integer.
456 #define Int32GetDatum(X) ((Datum) SET_4_BYTES(X))
460 * Returns 32-bit unsigned integer value of a datum.
463 #define DatumGetUInt32(X) ((uint32) GET_4_BYTES(X))
467 * Returns datum representation for a 32-bit unsigned integer.
470 #define UInt32GetDatum(X) ((Datum) SET_4_BYTES(X))
474 * Returns object identifier value of a datum.
477 #define DatumGetObjectId(X) ((Oid) GET_4_BYTES(X))
481 * Returns datum representation for an object identifier.
484 #define ObjectIdGetDatum(X) ((Datum) SET_4_BYTES(X))
487 * DatumGetTransactionId
488 * Returns transaction identifier value of a datum.
491 #define DatumGetTransactionId(X) ((TransactionId) GET_4_BYTES(X))
494 * TransactionIdGetDatum
495 * Returns datum representation for a transaction identifier.
498 #define TransactionIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
501 * MultiXactIdGetDatum
502 * Returns datum representation for a multixact identifier.
505 #define MultiXactIdGetDatum(X) ((Datum) SET_4_BYTES((X)))
509 * Returns command identifier value of a datum.
512 #define DatumGetCommandId(X) ((CommandId) GET_4_BYTES(X))
516 * Returns datum representation for a command identifier.
519 #define CommandIdGetDatum(X) ((Datum) SET_4_BYTES(X))
523 * Returns pointer value of a datum.
526 #define DatumGetPointer(X) ((Pointer) (X))
530 * Returns datum representation for a pointer.
533 #define PointerGetDatum(X) ((Datum) (X))
537 * Returns C string (null-terminated string) value of a datum.
539 * Note: C string is not a full-fledged Postgres type at present,
540 * but type input functions use this conversion for their inputs.
543 #define DatumGetCString(X) ((char *) DatumGetPointer(X))
547 * Returns datum representation for a C string (null-terminated string).
549 * Note: C string is not a full-fledged Postgres type at present,
550 * but type output functions use this conversion for their outputs.
551 * Note: CString is pass-by-reference; caller must ensure the pointed-to
552 * value has adequate lifetime.
555 #define CStringGetDatum(X) PointerGetDatum(X)
559 * Returns name value of a datum.
562 #define DatumGetName(X) ((Name) DatumGetPointer(X))
566 * Returns datum representation for a name.
568 * Note: Name is pass-by-reference; caller must ensure the pointed-to
569 * value has adequate lifetime.
572 #define NameGetDatum(X) PointerGetDatum(X)
576 * Returns 64-bit integer value of a datum.
578 * Note: this macro hides whether int64 is pass by value or by reference.
581 #ifdef USE_FLOAT8_BYVAL
582 #define DatumGetInt64(X) ((int64) GET_8_BYTES(X))
584 #define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))
589 * Returns datum representation for a 64-bit integer.
591 * Note: if int64 is pass by reference, this function returns a reference
595 #ifdef USE_FLOAT8_BYVAL
596 #define Int64GetDatum(X) ((Datum) SET_8_BYTES(X))
598 extern Datum Int64GetDatum(int64 X);
603 * Returns 4-byte floating point value of a datum.
605 * Note: this macro hides whether float4 is pass by value or by reference.
608 #ifdef USE_FLOAT4_BYVAL
609 extern float4 DatumGetFloat4(Datum X);
611 #define DatumGetFloat4(X) (* ((float4 *) DatumGetPointer(X)))
616 * Returns datum representation for a 4-byte floating point number.
618 * Note: if float4 is pass by reference, this function returns a reference
622 extern Datum Float4GetDatum(float4 X);
626 * Returns 8-byte floating point value of a datum.
628 * Note: this macro hides whether float8 is pass by value or by reference.
631 #ifdef USE_FLOAT8_BYVAL
632 extern float8 DatumGetFloat8(Datum X);
634 #define DatumGetFloat8(X) (* ((float8 *) DatumGetPointer(X)))
639 * Returns datum representation for an 8-byte floating point number.
641 * Note: if float8 is pass by reference, this function returns a reference
645 extern Datum Float8GetDatum(float8 X);
653 * These macros are intended to allow writing code that does not depend on
654 * whether int64, float8, float4 are pass-by-reference types, while not
655 * sacrificing performance when they are. The argument must be a variable
656 * that will exist and have the same value for as long as the Datum is needed.
657 * In the pass-by-ref case, the address of the variable is taken to use as
658 * the Datum. In the pass-by-val case, these will be the same as the non-Fast
662 #ifdef USE_FLOAT8_BYVAL
663 #define Int64GetDatumFast(X) Int64GetDatum(X)
664 #define Float8GetDatumFast(X) Float8GetDatum(X)
666 #define Int64GetDatumFast(X) PointerGetDatum(&(X))
667 #define Float8GetDatumFast(X) PointerGetDatum(&(X))
670 #ifdef USE_FLOAT4_BYVAL
671 #define Float4GetDatumFast(X) Float4GetDatum(X)
673 #define Float4GetDatumFast(X) PointerGetDatum(&(X))
677 /* ----------------------------------------------------------------
678 * Section 3: exception handling backend support
679 * ----------------------------------------------------------------
683 * Backend only infrastructure for the the assertion-related macros in c.h.
685 * ExceptionalCondition must be present even when assertions are not enabled.
687 extern void ExceptionalCondition(const char *conditionName,
688 const char *errorType,
689 const char *fileName, int lineNumber) __attribute__((noreturn));
691 #endif /* POSTGRES_H */