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Diffstat (limited to 'src/include/access/tupmacs.h')
| -rw-r--r-- | src/include/access/tupmacs.h | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/src/include/access/tupmacs.h b/src/include/access/tupmacs.h new file mode 100644 index 0000000..70157cf --- /dev/null +++ b/src/include/access/tupmacs.h @@ -0,0 +1,247 @@ +/*------------------------------------------------------------------------- + * + * tupmacs.h + * Tuple macros used by both index tuples and heap tuples. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/access/tupmacs.h + * + *------------------------------------------------------------------------- + */ +#ifndef TUPMACS_H +#define TUPMACS_H + +#include "catalog/pg_type_d.h" /* for TYPALIGN macros */ + + +/* + * Check a tuple's null bitmap to determine whether the attribute is null. + * Note that a 0 in the null bitmap indicates a null, while 1 indicates + * non-null. + */ +#define att_isnull(ATT, BITS) (!((BITS)[(ATT) >> 3] & (1 << ((ATT) & 0x07)))) + +/* + * Given a Form_pg_attribute and a pointer into a tuple's data area, + * return the correct value or pointer. + * + * We return a Datum value in all cases. If the attribute has "byval" false, + * we return the same pointer into the tuple data area that we're passed. + * Otherwise, we return the correct number of bytes fetched from the data + * area and extended to Datum form. + * + * On machines where Datum is 8 bytes, we support fetching 8-byte byval + * attributes; otherwise, only 1, 2, and 4-byte values are supported. + * + * Note that T must already be properly aligned for this to work correctly. + */ +#define fetchatt(A,T) fetch_att(T, (A)->attbyval, (A)->attlen) + +/* + * Same, but work from byval/len parameters rather than Form_pg_attribute. + */ +#if SIZEOF_DATUM == 8 + +#define fetch_att(T,attbyval,attlen) \ +( \ + (attbyval) ? \ + ( \ + (attlen) == (int) sizeof(Datum) ? \ + *((Datum *)(T)) \ + : \ + ( \ + (attlen) == (int) sizeof(int32) ? \ + Int32GetDatum(*((int32 *)(T))) \ + : \ + ( \ + (attlen) == (int) sizeof(int16) ? \ + Int16GetDatum(*((int16 *)(T))) \ + : \ + ( \ + AssertMacro((attlen) == 1), \ + CharGetDatum(*((char *)(T))) \ + ) \ + ) \ + ) \ + ) \ + : \ + PointerGetDatum((char *) (T)) \ +) +#else /* SIZEOF_DATUM != 8 */ + +#define fetch_att(T,attbyval,attlen) \ +( \ + (attbyval) ? \ + ( \ + (attlen) == (int) sizeof(int32) ? \ + Int32GetDatum(*((int32 *)(T))) \ + : \ + ( \ + (attlen) == (int) sizeof(int16) ? \ + Int16GetDatum(*((int16 *)(T))) \ + : \ + ( \ + AssertMacro((attlen) == 1), \ + CharGetDatum(*((char *)(T))) \ + ) \ + ) \ + ) \ + : \ + PointerGetDatum((char *) (T)) \ +) +#endif /* SIZEOF_DATUM == 8 */ + +/* + * att_align_datum aligns the given offset as needed for a datum of alignment + * requirement attalign and typlen attlen. attdatum is the Datum variable + * we intend to pack into a tuple (it's only accessed if we are dealing with + * a varlena type). Note that this assumes the Datum will be stored as-is; + * callers that are intending to convert non-short varlena datums to short + * format have to account for that themselves. + */ +#define att_align_datum(cur_offset, attalign, attlen, attdatum) \ +( \ + ((attlen) == -1 && VARATT_IS_SHORT(DatumGetPointer(attdatum))) ? \ + (uintptr_t) (cur_offset) : \ + att_align_nominal(cur_offset, attalign) \ +) + +/* + * att_align_pointer performs the same calculation as att_align_datum, + * but is used when walking a tuple. attptr is the current actual data + * pointer; when accessing a varlena field we have to "peek" to see if we + * are looking at a pad byte or the first byte of a 1-byte-header datum. + * (A zero byte must be either a pad byte, or the first byte of a correctly + * aligned 4-byte length word; in either case we can align safely. A non-zero + * byte must be either a 1-byte length word, or the first byte of a correctly + * aligned 4-byte length word; in either case we need not align.) + * + * Note: some callers pass a "char *" pointer for cur_offset. This is + * a bit of a hack but should work all right as long as uintptr_t is the + * correct width. + */ +#define att_align_pointer(cur_offset, attalign, attlen, attptr) \ +( \ + ((attlen) == -1 && VARATT_NOT_PAD_BYTE(attptr)) ? \ + (uintptr_t) (cur_offset) : \ + att_align_nominal(cur_offset, attalign) \ +) + +/* + * att_align_nominal aligns the given offset as needed for a datum of alignment + * requirement attalign, ignoring any consideration of packed varlena datums. + * There are three main use cases for using this macro directly: + * * we know that the att in question is not varlena (attlen != -1); + * in this case it is cheaper than the above macros and just as good. + * * we need to estimate alignment padding cost abstractly, ie without + * reference to a real tuple. We must assume the worst case that + * all varlenas are aligned. + * * within arrays, we unconditionally align varlenas (XXX this should be + * revisited, probably). + * + * The attalign cases are tested in what is hopefully something like their + * frequency of occurrence. + */ +#define att_align_nominal(cur_offset, attalign) \ +( \ + ((attalign) == TYPALIGN_INT) ? INTALIGN(cur_offset) : \ + (((attalign) == TYPALIGN_CHAR) ? (uintptr_t) (cur_offset) : \ + (((attalign) == TYPALIGN_DOUBLE) ? DOUBLEALIGN(cur_offset) : \ + ( \ + AssertMacro((attalign) == TYPALIGN_SHORT), \ + SHORTALIGN(cur_offset) \ + ))) \ +) + +/* + * att_addlength_datum increments the given offset by the space needed for + * the given Datum variable. attdatum is only accessed if we are dealing + * with a variable-length attribute. + */ +#define att_addlength_datum(cur_offset, attlen, attdatum) \ + att_addlength_pointer(cur_offset, attlen, DatumGetPointer(attdatum)) + +/* + * att_addlength_pointer performs the same calculation as att_addlength_datum, + * but is used when walking a tuple --- attptr is the pointer to the field + * within the tuple. + * + * Note: some callers pass a "char *" pointer for cur_offset. This is + * actually perfectly OK, but probably should be cleaned up along with + * the same practice for att_align_pointer. + */ +#define att_addlength_pointer(cur_offset, attlen, attptr) \ +( \ + ((attlen) > 0) ? \ + ( \ + (cur_offset) + (attlen) \ + ) \ + : (((attlen) == -1) ? \ + ( \ + (cur_offset) + VARSIZE_ANY(attptr) \ + ) \ + : \ + ( \ + AssertMacro((attlen) == -2), \ + (cur_offset) + (strlen((char *) (attptr)) + 1) \ + )) \ +) + +/* + * store_att_byval is a partial inverse of fetch_att: store a given Datum + * value into a tuple data area at the specified address. However, it only + * handles the byval case, because in typical usage the caller needs to + * distinguish by-val and by-ref cases anyway, and so a do-it-all macro + * wouldn't be convenient. + */ +#if SIZEOF_DATUM == 8 + +#define store_att_byval(T,newdatum,attlen) \ + do { \ + switch (attlen) \ + { \ + case sizeof(char): \ + *(char *) (T) = DatumGetChar(newdatum); \ + break; \ + case sizeof(int16): \ + *(int16 *) (T) = DatumGetInt16(newdatum); \ + break; \ + case sizeof(int32): \ + *(int32 *) (T) = DatumGetInt32(newdatum); \ + break; \ + case sizeof(Datum): \ + *(Datum *) (T) = (newdatum); \ + break; \ + default: \ + elog(ERROR, "unsupported byval length: %d", \ + (int) (attlen)); \ + break; \ + } \ + } while (0) +#else /* SIZEOF_DATUM != 8 */ + +#define store_att_byval(T,newdatum,attlen) \ + do { \ + switch (attlen) \ + { \ + case sizeof(char): \ + *(char *) (T) = DatumGetChar(newdatum); \ + break; \ + case sizeof(int16): \ + *(int16 *) (T) = DatumGetInt16(newdatum); \ + break; \ + case sizeof(int32): \ + *(int32 *) (T) = DatumGetInt32(newdatum); \ + break; \ + default: \ + elog(ERROR, "unsupported byval length: %d", \ + (int) (attlen)); \ + break; \ + } \ + } while (0) +#endif /* SIZEOF_DATUM == 8 */ + +#endif |