codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * varatt.h4 *	  variable-length datatypes (TOAST support)5 *6 *7 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group8 * Portions Copyright (c) 1995, Regents of the University of California9 *10 * src/include/varatt.h11 *12 *-------------------------------------------------------------------------13 */14 15#ifndef VARATT_H16#define VARATT_H17 18/*19 * struct varatt_external is a traditional "TOAST pointer", that is, the20 * information needed to fetch a Datum stored out-of-line in a TOAST table.21 * The data is compressed if and only if the external size stored in22 * va_extinfo is less than va_rawsize - VARHDRSZ.23 *24 * This struct must not contain any padding, because we sometimes compare25 * these pointers using memcmp.26 *27 * Note that this information is stored unaligned within actual tuples, so28 * you need to memcpy from the tuple into a local struct variable before29 * you can look at these fields!  (The reason we use memcmp is to avoid30 * having to do that just to detect equality of two TOAST pointers...)31 */32typedef struct varatt_external33{34	int32		va_rawsize;		/* Original data size (includes header) */35	uint32		va_extinfo;		/* External saved size (without header) and36								 * compression method */37	Oid			va_valueid;		/* Unique ID of value within TOAST table */38	Oid			va_toastrelid;	/* RelID of TOAST table containing it */39}			varatt_external;40 41/*42 * These macros define the "saved size" portion of va_extinfo.  Its remaining43 * two high-order bits identify the compression method.44 */45#define VARLENA_EXTSIZE_BITS	3046#define VARLENA_EXTSIZE_MASK	((1U << VARLENA_EXTSIZE_BITS) - 1)47 48/*49 * struct varatt_indirect is a "TOAST pointer" representing an out-of-line50 * Datum that's stored in memory, not in an external toast relation.51 * The creator of such a Datum is entirely responsible that the referenced52 * storage survives for as long as referencing pointer Datums can exist.53 *54 * Note that just as for struct varatt_external, this struct is stored55 * unaligned within any containing tuple.56 */57typedef struct varatt_indirect58{59	struct varlena *pointer;	/* Pointer to in-memory varlena */60}			varatt_indirect;61 62/*63 * struct varatt_expanded is a "TOAST pointer" representing an out-of-line64 * Datum that is stored in memory, in some type-specific, not necessarily65 * physically contiguous format that is convenient for computation not66 * storage.  APIs for this, in particular the definition of struct67 * ExpandedObjectHeader, are in src/include/utils/expandeddatum.h.68 *69 * Note that just as for struct varatt_external, this struct is stored70 * unaligned within any containing tuple.71 */72typedef struct ExpandedObjectHeader ExpandedObjectHeader;73 74typedef struct varatt_expanded75{76	ExpandedObjectHeader *eohptr;77} varatt_expanded;78 79/*80 * Type tag for the various sorts of "TOAST pointer" datums.  The peculiar81 * value for VARTAG_ONDISK comes from a requirement for on-disk compatibility82 * with a previous notion that the tag field was the pointer datum's length.83 */84typedef enum vartag_external85{86	VARTAG_INDIRECT = 1,87	VARTAG_EXPANDED_RO = 2,88	VARTAG_EXPANDED_RW = 3,89	VARTAG_ONDISK = 1890} vartag_external;91 92/* this test relies on the specific tag values above */93#define VARTAG_IS_EXPANDED(tag) \94	(((tag) & ~1) == VARTAG_EXPANDED_RO)95 96#define VARTAG_SIZE(tag) \97	((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \98	 VARTAG_IS_EXPANDED(tag) ? sizeof(varatt_expanded) : \99	 (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \100	 (AssertMacro(false), 0))101 102/*103 * These structs describe the header of a varlena object that may have been104 * TOASTed.  Generally, don't reference these structs directly, but use the105 * macros below.106 *107 * We use separate structs for the aligned and unaligned cases because the108 * compiler might otherwise think it could generate code that assumes109 * alignment while touching fields of a 1-byte-header varlena.110 */111typedef union112{113	struct						/* Normal varlena (4-byte length) */114	{115		uint32		va_header;116		char		va_data[FLEXIBLE_ARRAY_MEMBER];117	}			va_4byte;118	struct						/* Compressed-in-line format */119	{120		uint32		va_header;121		uint32		va_tcinfo;	/* Original data size (excludes header) and122								 * compression method; see va_extinfo */123		char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */124	}			va_compressed;125} varattrib_4b;126 127typedef struct128{129	uint8		va_header;130	char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Data begins here */131} varattrib_1b;132 133/* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */134typedef struct135{136	uint8		va_header;		/* Always 0x80 or 0x01 */137	uint8		va_tag;			/* Type of datum */138	char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Type-specific data */139} varattrib_1b_e;140 141/*142 * Bit layouts for varlena headers on big-endian machines:143 *144 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)145 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)146 * 10000000 1-byte length word, unaligned, TOAST pointer147 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)148 *149 * Bit layouts for varlena headers on little-endian machines:150 *151 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)152 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)153 * 00000001 1-byte length word, unaligned, TOAST pointer154 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)155 *156 * The "xxx" bits are the length field (which includes itself in all cases).157 * In the big-endian case we mask to extract the length, in the little-endian158 * case we shift.  Note that in both cases the flag bits are in the physically159 * first byte.  Also, it is not possible for a 1-byte length word to be zero;160 * this lets us disambiguate alignment padding bytes from the start of an161 * unaligned datum.  (We now *require* pad bytes to be filled with zero!)162 *163 * In TOAST pointers the va_tag field (see varattrib_1b_e) is used to discern164 * the specific type and length of the pointer datum.165 */166 167/*168 * Endian-dependent macros.  These are considered internal --- use the169 * external macros below instead of using these directly.170 *171 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0172 * for such records. Hence you should usually check for IS_EXTERNAL before173 * checking for IS_1B.174 */175 176#ifdef WORDS_BIGENDIAN177 178#define VARATT_IS_4B(PTR) \179	((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)180#define VARATT_IS_4B_U(PTR) \181	((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)182#define VARATT_IS_4B_C(PTR) \183	((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)184#define VARATT_IS_1B(PTR) \185	((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)186#define VARATT_IS_1B_E(PTR) \187	((((varattrib_1b *) (PTR))->va_header) == 0x80)188#define VARATT_NOT_PAD_BYTE(PTR) \189	(*((uint8 *) (PTR)) != 0)190 191/* VARSIZE_4B() should only be used on known-aligned data */192#define VARSIZE_4B(PTR) \193	(((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)194#define VARSIZE_1B(PTR) \195	(((varattrib_1b *) (PTR))->va_header & 0x7F)196#define VARTAG_1B_E(PTR) \197	(((varattrib_1b_e *) (PTR))->va_tag)198 199#define SET_VARSIZE_4B(PTR,len) \200	(((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)201#define SET_VARSIZE_4B_C(PTR,len) \202	(((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)203#define SET_VARSIZE_1B(PTR,len) \204	(((varattrib_1b *) (PTR))->va_header = (len) | 0x80)205#define SET_VARTAG_1B_E(PTR,tag) \206	(((varattrib_1b_e *) (PTR))->va_header = 0x80, \207	 ((varattrib_1b_e *) (PTR))->va_tag = (tag))208 209#else							/* !WORDS_BIGENDIAN */210 211#define VARATT_IS_4B(PTR) \212	((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)213#define VARATT_IS_4B_U(PTR) \214	((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)215#define VARATT_IS_4B_C(PTR) \216	((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)217#define VARATT_IS_1B(PTR) \218	((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)219#define VARATT_IS_1B_E(PTR) \220	((((varattrib_1b *) (PTR))->va_header) == 0x01)221#define VARATT_NOT_PAD_BYTE(PTR) \222	(*((uint8 *) (PTR)) != 0)223 224/* VARSIZE_4B() should only be used on known-aligned data */225#define VARSIZE_4B(PTR) \226	((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)227#define VARSIZE_1B(PTR) \228	((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)229#define VARTAG_1B_E(PTR) \230	(((varattrib_1b_e *) (PTR))->va_tag)231 232#define SET_VARSIZE_4B(PTR,len) \233	(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))234#define SET_VARSIZE_4B_C(PTR,len) \235	(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)236#define SET_VARSIZE_1B(PTR,len) \237	(((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)238#define SET_VARTAG_1B_E(PTR,tag) \239	(((varattrib_1b_e *) (PTR))->va_header = 0x01, \240	 ((varattrib_1b_e *) (PTR))->va_tag = (tag))241 242#endif							/* WORDS_BIGENDIAN */243 244#define VARDATA_4B(PTR)		(((varattrib_4b *) (PTR))->va_4byte.va_data)245#define VARDATA_4B_C(PTR)	(((varattrib_4b *) (PTR))->va_compressed.va_data)246#define VARDATA_1B(PTR)		(((varattrib_1b *) (PTR))->va_data)247#define VARDATA_1B_E(PTR)	(((varattrib_1b_e *) (PTR))->va_data)248 249/*250 * Externally visible TOAST macros begin here.251 */252 253#define VARHDRSZ_EXTERNAL		offsetof(varattrib_1b_e, va_data)254#define VARHDRSZ_COMPRESSED		offsetof(varattrib_4b, va_compressed.va_data)255#define VARHDRSZ_SHORT			offsetof(varattrib_1b, va_data)256 257#define VARATT_SHORT_MAX		0x7F258#define VARATT_CAN_MAKE_SHORT(PTR) \259	(VARATT_IS_4B_U(PTR) && \260	 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)261#define VARATT_CONVERTED_SHORT_SIZE(PTR) \262	(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)263 264/*265 * In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),266 * VARDATA_ANY(), VARSIZE_ANY() and VARSIZE_ANY_EXHDR().  Elsewhere, call267 * PG_DETOAST_DATUM(), VARDATA() and VARSIZE().  Directly fetching an int16,268 * int32 or wider field in the struct representing the datum layout requires269 * aligned data.  memcpy() is alignment-oblivious, as are most operations on270 * datatypes, such as text, whose layout struct contains only char fields.271 *272 * Code assembling a new datum should call VARDATA() and SET_VARSIZE().273 * (Datums begin life untoasted.)274 *275 * Other macros here should usually be used only by tuple assembly/disassembly276 * code and code that specifically wants to work with still-toasted Datums.277 */278#define VARDATA(PTR)						VARDATA_4B(PTR)279#define VARSIZE(PTR)						VARSIZE_4B(PTR)280 281#define VARSIZE_SHORT(PTR)					VARSIZE_1B(PTR)282#define VARDATA_SHORT(PTR)					VARDATA_1B(PTR)283 284#define VARTAG_EXTERNAL(PTR)				VARTAG_1B_E(PTR)285#define VARSIZE_EXTERNAL(PTR)				(VARHDRSZ_EXTERNAL + VARTAG_SIZE(VARTAG_EXTERNAL(PTR)))286#define VARDATA_EXTERNAL(PTR)				VARDATA_1B_E(PTR)287 288#define VARATT_IS_COMPRESSED(PTR)			VARATT_IS_4B_C(PTR)289#define VARATT_IS_EXTERNAL(PTR)				VARATT_IS_1B_E(PTR)290#define VARATT_IS_EXTERNAL_ONDISK(PTR) \291	(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_ONDISK)292#define VARATT_IS_EXTERNAL_INDIRECT(PTR) \293	(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_INDIRECT)294#define VARATT_IS_EXTERNAL_EXPANDED_RO(PTR) \295	(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RO)296#define VARATT_IS_EXTERNAL_EXPANDED_RW(PTR) \297	(VARATT_IS_EXTERNAL(PTR) && VARTAG_EXTERNAL(PTR) == VARTAG_EXPANDED_RW)298#define VARATT_IS_EXTERNAL_EXPANDED(PTR) \299	(VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))300#define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \301	(VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))302#define VARATT_IS_SHORT(PTR)				VARATT_IS_1B(PTR)303#define VARATT_IS_EXTENDED(PTR)				(!VARATT_IS_4B_U(PTR))304 305#define SET_VARSIZE(PTR, len)				SET_VARSIZE_4B(PTR, len)306#define SET_VARSIZE_SHORT(PTR, len)			SET_VARSIZE_1B(PTR, len)307#define SET_VARSIZE_COMPRESSED(PTR, len)	SET_VARSIZE_4B_C(PTR, len)308 309#define SET_VARTAG_EXTERNAL(PTR, tag)		SET_VARTAG_1B_E(PTR, tag)310 311#define VARSIZE_ANY(PTR) \312	(VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR) : \313	 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \314	  VARSIZE_4B(PTR)))315 316/* Size of a varlena data, excluding header */317#define VARSIZE_ANY_EXHDR(PTR) \318	(VARATT_IS_1B_E(PTR) ? VARSIZE_EXTERNAL(PTR)-VARHDRSZ_EXTERNAL : \319	 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \320	  VARSIZE_4B(PTR)-VARHDRSZ))321 322/* caution: this will not work on an external or compressed-in-line Datum */323/* caution: this will return a possibly unaligned pointer */324#define VARDATA_ANY(PTR) \325	 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))326 327/* Decompressed size and compression method of a compressed-in-line Datum */328#define VARDATA_COMPRESSED_GET_EXTSIZE(PTR) \329	(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo & VARLENA_EXTSIZE_MASK)330#define VARDATA_COMPRESSED_GET_COMPRESS_METHOD(PTR) \331	(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo >> VARLENA_EXTSIZE_BITS)332 333/* Same for external Datums; but note argument is a struct varatt_external */334#define VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) \335	((toast_pointer).va_extinfo & VARLENA_EXTSIZE_MASK)336#define VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer) \337	((toast_pointer).va_extinfo >> VARLENA_EXTSIZE_BITS)338 339#define VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer, len, cm) \340	do { \341		Assert((cm) == TOAST_PGLZ_COMPRESSION_ID || \342			   (cm) == TOAST_LZ4_COMPRESSION_ID); \343		((toast_pointer).va_extinfo = \344			(len) | ((uint32) (cm) << VARLENA_EXTSIZE_BITS)); \345	} while (0)346 347/*348 * Testing whether an externally-stored value is compressed now requires349 * comparing size stored in va_extinfo (the actual length of the external data)350 * to rawsize (the original uncompressed datum's size).  The latter includes351 * VARHDRSZ overhead, the former doesn't.  We never use compression unless it352 * actually saves space, so we expect either equality or less-than.353 */354#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \355	(VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) < \356	 (toast_pointer).va_rawsize - VARHDRSZ)357 358#endif359