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Diffstat (limited to 'src/backend/access/hash/hashfunc.c')
| -rw-r--r-- | src/backend/access/hash/hashfunc.c | 207 |
1 files changed, 0 insertions, 207 deletions
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c deleted file mode 100644 index fb58bccf00b..00000000000 --- a/src/backend/access/hash/hashfunc.c +++ /dev/null @@ -1,207 +0,0 @@ -/*------------------------------------------------------------------------- - * - * hashfunc.c - * Comparison functions for hash access method. - * - * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/hash/hashfunc.c,v 1.34 2002/06/20 20:29:24 momjian Exp $ - * - * NOTES - * These functions are stored in pg_amproc. For each operator class - * defined on hash tables, they compute the hash value of the argument. - * - *------------------------------------------------------------------------- - */ - -#include "postgres.h" - -#include "access/hash.h" - - -Datum -hashchar(PG_FUNCTION_ARGS) -{ - PG_RETURN_UINT32(~((uint32) PG_GETARG_CHAR(0))); -} - -Datum -hashint2(PG_FUNCTION_ARGS) -{ - PG_RETURN_UINT32(~((uint32) PG_GETARG_INT16(0))); -} - -Datum -hashint4(PG_FUNCTION_ARGS) -{ - PG_RETURN_UINT32(~PG_GETARG_UINT32(0)); -} - -Datum -hashint8(PG_FUNCTION_ARGS) -{ - /* we just use the low 32 bits... */ - PG_RETURN_UINT32(~((uint32) PG_GETARG_INT64(0))); -} - -Datum -hashoid(PG_FUNCTION_ARGS) -{ - PG_RETURN_UINT32(~((uint32) PG_GETARG_OID(0))); -} - -Datum -hashfloat4(PG_FUNCTION_ARGS) -{ - float4 key = PG_GETARG_FLOAT4(0); - - return hash_any((unsigned char *) &key, sizeof(key)); -} - -Datum -hashfloat8(PG_FUNCTION_ARGS) -{ - float8 key = PG_GETARG_FLOAT8(0); - - return hash_any((unsigned char *) &key, sizeof(key)); -} - -Datum -hashoidvector(PG_FUNCTION_ARGS) -{ - Oid *key = (Oid *) PG_GETARG_POINTER(0); - - return hash_any((unsigned char *) key, INDEX_MAX_KEYS * sizeof(Oid)); -} - -/* - * Note: hashint2vector currently can't be used as a user hash table - * hash function, because it has no pg_proc entry. We only need it - * for catcache indexing. - */ -Datum -hashint2vector(PG_FUNCTION_ARGS) -{ - int16 *key = (int16 *) PG_GETARG_POINTER(0); - - return hash_any((unsigned char *) key, INDEX_MAX_KEYS * sizeof(int16)); -} - -Datum -hashname(PG_FUNCTION_ARGS) -{ - char *key = NameStr(*PG_GETARG_NAME(0)); - int keylen = strlen(key); - - Assert(keylen < NAMEDATALEN); /* else it's not truncated correctly */ - - return hash_any((unsigned char *) key, keylen); -} - -/* - * hashvarlena() can be used for any varlena datatype in which there are - * no non-significant bits, ie, distinct bitpatterns never compare as equal. - */ -Datum -hashvarlena(PG_FUNCTION_ARGS) -{ - struct varlena *key = PG_GETARG_VARLENA_P(0); - Datum result; - - result = hash_any((unsigned char *) VARDATA(key), - VARSIZE(key) - VARHDRSZ); - - /* Avoid leaking memory for toasted inputs */ - PG_FREE_IF_COPY(key, 0); - - return result; -} - -/* - * This hash function was written by Bob Jenkins - * (bob_jenkins@burtleburtle.net), and superficially adapted - * for PostgreSQL by Neil Conway. For more information on this - * hash function, see http://burtleburtle.net/bob/hash/doobs.html, - * or Bob's article in Dr. Dobb's Journal, Sept. 1997. - */ - -/*---------- - * mix -- mix 3 32-bit values reversibly. - * For every delta with one or two bits set, and the deltas of all three - * high bits or all three low bits, whether the original value of a,b,c - * is almost all zero or is uniformly distributed, - * - If mix() is run forward or backward, at least 32 bits in a,b,c - * have at least 1/4 probability of changing. - * - If mix() is run forward, every bit of c will change between 1/3 and - * 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.) - *---------- - */ -#define mix(a,b,c) \ -{ \ - a -= b; a -= c; a ^= (c>>13); \ - b -= c; b -= a; b ^= (a<<8); \ - c -= a; c -= b; c ^= (b>>13); \ - a -= b; a -= c; a ^= (c>>12); \ - b -= c; b -= a; b ^= (a<<16); \ - c -= a; c -= b; c ^= (b>>5); \ - a -= b; a -= c; a ^= (c>>3); \ - b -= c; b -= a; b ^= (a<<10); \ - c -= a; c -= b; c ^= (b>>15); \ -} - -/* - * hash_any() -- hash a variable-length key into a 32-bit value - * k : the key (the unaligned variable-length array of bytes) - * len : the length of the key, counting by bytes - * - * Returns a uint32 value. Every bit of the key affects every bit of - * the return value. Every 1-bit and 2-bit delta achieves avalanche. - * About 6*len+35 instructions. The best hash table sizes are powers - * of 2. There is no need to do mod a prime (mod is sooo slow!). - * If you need less than 32 bits, use a bitmask. - */ -Datum -hash_any(register const unsigned char *k, register int keylen) -{ - register uint32 a,b,c,len; - - /* Set up the internal state */ - len = keylen; - a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */ - c = 3923095; /* initialize with an arbitrary value */ - - /* handle most of the key */ - while (len >= 12) - { - a += (k[0] +((uint32)k[1]<<8) +((uint32)k[2]<<16) +((uint32)k[3]<<24)); - b += (k[4] +((uint32)k[5]<<8) +((uint32)k[6]<<16) +((uint32)k[7]<<24)); - c += (k[8] +((uint32)k[9]<<8) +((uint32)k[10]<<16)+((uint32)k[11]<<24)); - mix(a,b,c); - k += 12; len -= 12; - } - - /* handle the last 11 bytes */ - c += keylen; - switch (len) /* all the case statements fall through */ - { - case 11: c+=((uint32)k[10]<<24); - case 10: c+=((uint32)k[9]<<16); - case 9 : c+=((uint32)k[8]<<8); - /* the first byte of c is reserved for the length */ - case 8 : b+=((uint32)k[7]<<24); - case 7 : b+=((uint32)k[6]<<16); - case 6 : b+=((uint32)k[5]<<8); - case 5 : b+=k[4]; - case 4 : a+=((uint32)k[3]<<24); - case 3 : a+=((uint32)k[2]<<16); - case 2 : a+=((uint32)k[1]<<8); - case 1 : a+=k[0]; - /* case 0: nothing left to add */ - } - mix(a,b,c); - /* report the result */ - return UInt32GetDatum(c); -} |