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Code review for improved-hashing patch. Fix some portability issues
(char != unsigned char, Datum != uint32); make use of new hash code in dynahash hash tables and hash joins.
1 parent 1eb31d1 commit c422b5c

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11 files changed

+114
-190
lines changed

11 files changed

+114
-190
lines changed

‎src/backend/access/hash/hash.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/hash/hash.c,v 1.55 2002/03/06 20:49:37 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/hash/hash.c,v 1.56 2002/03/09 17:35:35 tgl Exp $
1212
*
1313
* NOTES
1414
* This file contains only the public interface routines.
@@ -164,6 +164,9 @@ hashinsert(PG_FUNCTION_ARGS)
164164
Datum *datum = (Datum *) PG_GETARG_POINTER(1);
165165
char *nulls = (char *) PG_GETARG_POINTER(2);
166166
ItemPointer ht_ctid = (ItemPointer) PG_GETARG_POINTER(3);
167+
#ifdef NOT_USED
168+
Relation heapRel = (Relation) PG_GETARG_POINTER(4);
169+
#endif
167170

168171
InsertIndexResult res;
169172
HashItem hitem;

‎src/backend/access/hash/hashfunc.c

Lines changed: 57 additions & 56 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/hash/hashfunc.c,v 1.32 2002/03/06 20:49:38 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/hash/hashfunc.c,v 1.33 2002/03/09 17:35:35 tgl Exp $
1212
*
1313
* NOTES
1414
* These functions are stored in pg_amproc. For each operator class
@@ -58,23 +58,23 @@ hashfloat4(PG_FUNCTION_ARGS)
5858
{
5959
float4 key = PG_GETARG_FLOAT4(0);
6060

61-
return hash_any((char *) &key, sizeof(key));
61+
return hash_any((unsigned char *) &key, sizeof(key));
6262
}
6363

6464
Datum
6565
hashfloat8(PG_FUNCTION_ARGS)
6666
{
6767
float8 key = PG_GETARG_FLOAT8(0);
6868

69-
return hash_any((char *) &key, sizeof(key));
69+
return hash_any((unsigned char *) &key, sizeof(key));
7070
}
7171

7272
Datum
7373
hashoidvector(PG_FUNCTION_ARGS)
7474
{
7575
Oid *key = (Oid *) PG_GETARG_POINTER(0);
7676

77-
return hash_any((char *) key, INDEX_MAX_KEYS * sizeof(Oid));
77+
return hash_any((unsigned char *) key, INDEX_MAX_KEYS * sizeof(Oid));
7878
}
7979

8080
/*
@@ -87,17 +87,18 @@ hashint2vector(PG_FUNCTION_ARGS)
8787
{
8888
int16 *key = (int16 *) PG_GETARG_POINTER(0);
8989

90-
return hash_any((char *) key, INDEX_MAX_KEYS * sizeof(int16));
90+
return hash_any((unsigned char *) key, INDEX_MAX_KEYS * sizeof(int16));
9191
}
9292

9393
Datum
9494
hashname(PG_FUNCTION_ARGS)
9595
{
9696
char *key = NameStr(*PG_GETARG_NAME(0));
97+
int keylen = strlen(key);
9798

98-
Assert(strlen(key) <= NAMEDATALEN);
99+
Assert(keylen < NAMEDATALEN); /* else it's not truncated correctly */
99100

100-
return hash_any(key, strlen(key));
101+
return hash_any((unsigned char *) key, keylen);
101102
}
102103

103104
/*
@@ -110,21 +111,24 @@ hashvarlena(PG_FUNCTION_ARGS)
110111
struct varlena *key = PG_GETARG_VARLENA_P(0);
111112
Datum result;
112113

113-
result = hash_any(VARDATA(key), VARSIZE(key) - VARHDRSZ);
114+
result = hash_any((unsigned char *) VARDATA(key),
115+
VARSIZE(key) - VARHDRSZ);
114116

115117
/* Avoid leaking memory for toasted inputs */
116118
PG_FREE_IF_COPY(key, 0);
117119

118120
return result;
119121
}
120122

121-
/* This hash function was written by Bob Jenkins
123+
/*
124+
* This hash function was written by Bob Jenkins
122125
* (bob_jenkins@burtleburtle.net), and superficially adapted
123126
* for PostgreSQL by Neil Conway. For more information on this
124-
* hash function, see http://burtleburtle.net/bob/hash/doobs.html
127+
* hash function, see http://burtleburtle.net/bob/hash/doobs.html,
128+
* or Bob's article in Dr. Dobb's Journal, Sept. 1997.
125129
*/
126130

127-
/*
131+
/*----------
128132
* mix -- mix 3 32-bit values reversibly.
129133
* For every delta with one or two bits set, and the deltas of all three
130134
* high bits or all three low bits, whether the original value of a,b,c
@@ -133,6 +137,7 @@ hashvarlena(PG_FUNCTION_ARGS)
133137
* have at least 1/4 probability of changing.
134138
* - If mix() is run forward, every bit of c will change between 1/3 and
135139
* 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
140+
*----------
136141
*/
137142
#define mix(a,b,c) \
138143
{ \
@@ -151,56 +156,52 @@ hashvarlena(PG_FUNCTION_ARGS)
151156
* hash_any() -- hash a variable-length key into a 32-bit value
152157
* k : the key (the unaligned variable-length array of bytes)
153158
* len : the length of the key, counting by bytes
154-
* Returns a 32-bit value. Every bit of the key affects every bit of
159+
*
160+
* Returns a uint32 value. Every bit of the key affects every bit of
155161
* the return value. Every 1-bit and 2-bit delta achieves avalanche.
156162
* About 6*len+35 instructions. The best hash table sizes are powers
157163
* of 2. There is no need to do mod a prime (mod is sooo slow!).
158164
* If you need less than 32 bits, use a bitmask.
159165
*/
160166
Datum
161-
hash_any(register const char *k, register int keylen)
167+
hash_any(register const unsigned char *k, register int keylen)
162168
{
163-
register Datum a,b,c,len;
164-
165-
/* Set up the internal state */
166-
len = keylen;
167-
a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
168-
/* Another arbitrary value. If the hash function is called
169-
* multiple times, this could be the previously generated
170-
* hash value; however, the interface currently doesn't allow
171-
* this. AFAIK this isn't a big deal.
172-
*/
173-
c = 3923095;
174-
175-
/* handle most of the key */
176-
while (len >= 12)
177-
{
178-
a += (k[0] +((Datum)k[1]<<8) +((Datum)k[2]<<16) +((Datum)k[3]<<24));
179-
b += (k[4] +((Datum)k[5]<<8) +((Datum)k[6]<<16) +((Datum)k[7]<<24));
180-
c += (k[8] +((Datum)k[9]<<8) +((Datum)k[10]<<16)+((Datum)k[11]<<24));
181-
mix(a,b,c);
182-
k += 12; len -= 12;
183-
}
184-
185-
/* handle the last 11 bytes */
186-
c += keylen;
187-
switch(len) /* all the case statements fall through */
188-
{
189-
case 11: c+=((Datum)k[10]<<24);
190-
case 10: c+=((Datum)k[9]<<16);
191-
case 9 : c+=((Datum)k[8]<<8);
192-
/* the first byte of c is reserved for the length */
193-
case 8 : b+=((Datum)k[7]<<24);
194-
case 7 : b+=((Datum)k[6]<<16);
195-
case 6 : b+=((Datum)k[5]<<8);
196-
case 5 : b+=k[4];
197-
case 4 : a+=((Datum)k[3]<<24);
198-
case 3 : a+=((Datum)k[2]<<16);
199-
case 2 : a+=((Datum)k[1]<<8);
200-
case 1 : a+=k[0];
201-
/* case 0: nothing left to add */
202-
}
203-
mix(a,b,c);
204-
/* report the result */
205-
return c;
169+
register uint32 a,b,c,len;
170+
171+
/* Set up the internal state */
172+
len = keylen;
173+
a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
174+
c = 3923095; /* initialize with an arbitrary value */
175+
176+
/* handle most of the key */
177+
while (len >= 12)
178+
{
179+
a += (k[0] +((uint32)k[1]<<8) +((uint32)k[2]<<16) +((uint32)k[3]<<24));
180+
b += (k[4] +((uint32)k[5]<<8) +((uint32)k[6]<<16) +((uint32)k[7]<<24));
181+
c += (k[8] +((uint32)k[9]<<8) +((uint32)k[10]<<16)+((uint32)k[11]<<24));
182+
mix(a,b,c);
183+
k += 12; len -= 12;
184+
}
185+
186+
/* handle the last 11 bytes */
187+
c += keylen;
188+
switch (len) /* all the case statements fall through */
189+
{
190+
case 11: c+=((uint32)k[10]<<24);
191+
case 10: c+=((uint32)k[9]<<16);
192+
case 9 : c+=((uint32)k[8]<<8);
193+
/* the first byte of c is reserved for the length */
194+
case 8 : b+=((uint32)k[7]<<24);
195+
case 7 : b+=((uint32)k[6]<<16);
196+
case 6 : b+=((uint32)k[5]<<8);
197+
case 5 : b+=k[4];
198+
case 4 : a+=((uint32)k[3]<<24);
199+
case 3 : a+=((uint32)k[2]<<16);
200+
case 2 : a+=((uint32)k[1]<<8);
201+
case 1 : a+=k[0];
202+
/* case 0: nothing left to add */
203+
}
204+
mix(a,b,c);
205+
/* report the result */
206+
return UInt32GetDatum(c);
206207
}

‎src/backend/executor/nodeHash.c

Lines changed: 16 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
*
10-
* $Id: nodeHash.c,v 1.61 2002/03/06 20:49:44 momjian Exp $
10+
* $Id: nodeHash.c,v 1.62 2002/03/09 17:35:35 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -22,6 +22,7 @@
2222
#include <sys/types.h>
2323
#include <math.h>
2424

25+
#include "access/hash.h"
2526
#include "executor/execdebug.h"
2627
#include "executor/nodeHash.h"
2728
#include "executor/nodeHashjoin.h"
@@ -31,7 +32,7 @@
3132
#include "utils/lsyscache.h"
3233

3334

34-
static int hashFunc(Datum key, int len, bool byVal);
35+
static uint32 hashFunc(Datum key, int len, bool byVal);
3536

3637
/* ----------------------------------------------------------------
3738
* ExecHash
@@ -553,7 +554,7 @@ ExecHashGetBucket(HashJoinTable hashtable,
553554
bucketno = hashFunc(keyval,
554555
(int) hashtable->typLen,
555556
hashtable->typByVal)
556-
% hashtable->totalbuckets;
557+
% (uint32) hashtable->totalbuckets;
557558
}
558559

559560
#ifdef HJDEBUG
@@ -624,30 +625,29 @@ ExecScanHashBucket(HashJoinState *hjstate,
624625
/* ----------------------------------------------------------------
625626
* hashFunc
626627
*
627-
* the hash function, copied from Margo
628+
* the hash function for hash joins
628629
*
629630
* XXX this probably ought to be replaced with datatype-specific
630631
* hash functions, such as those already implemented for hash indexes.
631632
* ----------------------------------------------------------------
632633
*/
633-
static int
634+
static uint32
634635
hashFunc(Datum key, int len, bool byVal)
635636
{
636-
unsigned int h = 0;
637+
unsigned char *k;
637638

638639
if (byVal)
639640
{
640641
/*
641-
* If it's a by-value data type, use the 'len' least significant
642-
* bytes of the Datum value. This should do the right thing on
643-
* either bigendian or littleendian hardware --- see the Datum
644-
* access macros in c.h.
642+
* If it's a by-value data type, just hash the whole Datum value.
643+
* This assumes that datatypes narrower than Datum are consistently
644+
* padded (either zero-extended or sign-extended, but not random
645+
* bits) to fill Datum; see the XXXGetDatum macros in postgres.h.
646+
* NOTE: it would not work to do hash_any(&key, len) since this
647+
* would get the wrong bytes on a big-endian machine.
645648
*/
646-
while (len-- > 0)
647-
{
648-
h = (h * PRIME1) ^ (key & 0xFF);
649-
key >>= 8;
650-
}
649+
k = (unsigned char *) &key;
650+
len = sizeof(Datum);
651651
}
652652
else
653653
{
@@ -662,8 +662,6 @@ hashFunc(Datum key, int len, bool byVal)
662662
* freeing the detoasted copy; that happens for free when the
663663
* per-tuple memory context is reset in ExecHashGetBucket.)
664664
*/
665-
unsigned char *k;
666-
667665
if (len < 0)
668666
{
669667
struct varlena *vkey = PG_DETOAST_DATUM(key);
@@ -673,12 +671,9 @@ hashFunc(Datum key, int len, bool byVal)
673671
}
674672
else
675673
k = (unsigned char *) DatumGetPointer(key);
676-
677-
while (len-- > 0)
678-
h = (h * PRIME1) ^ (*k++);
679674
}
680675

681-
return h % PRIME2;
676+
return DatumGetUInt32(hash_any(k, len));
682677
}
683678

684679
/* ----------------------------------------------------------------

‎src/backend/utils/adt/date.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.64 2001/11/21 05:57:33 thomas Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.65 2002/03/09 17:35:35 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1116,7 +1116,7 @@ timetz_hash(PG_FUNCTION_ARGS)
11161116
* sizeof(TimeTzADT), so that any garbage pad bytes in the structure
11171117
* won't be included in the hash!
11181118
*/
1119-
return hash_any((char *) key, sizeof(double) + sizeof(int4));
1119+
return hash_any((unsigned char *) key, sizeof(double) + sizeof(int4));
11201120
}
11211121

11221122
Datum

‎src/backend/utils/adt/mac.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
/*
22
* PostgreSQL type definitions for MAC addresses.
33
*
4-
* $Header: /cvsroot/pgsql/src/backend/utils/adt/mac.c,v 1.21 2001/08/21 21:23:21 tgl Exp $
4+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/mac.c,v 1.22 2002/03/09 17:35:35 tgl Exp $
55
*/
66

77
#include "postgres.h"
@@ -230,7 +230,7 @@ hashmacaddr(PG_FUNCTION_ARGS)
230230
{
231231
macaddr *key = PG_GETARG_MACADDR_P(0);
232232

233-
return hash_any((char *) key, sizeof(macaddr));
233+
return hash_any((unsigned char *) key, sizeof(macaddr));
234234
}
235235

236236
/*

‎src/backend/utils/adt/timestamp.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.64 2002/03/06 06:10:18 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.65 2002/03/09 17:35:36 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1017,7 +1017,7 @@ interval_hash(PG_FUNCTION_ARGS)
10171017
* sizeof(Interval), so that any garbage pad bytes in the structure
10181018
* won't be included in the hash!
10191019
*/
1020-
return hash_any((char *) key, sizeof(double) + sizeof(int4));
1020+
return hash_any((unsigned char *) key, sizeof(double) + sizeof(int4));
10211021
}
10221022

10231023
/* overlaps_timestamp() --- implements the SQL92 OVERLAPS operator.

‎src/backend/utils/adt/varchar.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.87 2001/11/18 12:07:07 ishii Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.88 2002/03/09 17:35:36 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -791,7 +791,7 @@ hashbpchar(PG_FUNCTION_ARGS)
791791
keydata = VARDATA(key);
792792
keylen = bcTruelen(key);
793793

794-
result = hash_any(keydata, keylen);
794+
result = hash_any((unsigned char *) keydata, keylen);
795795

796796
/* Avoid leaking memory for toasted inputs */
797797
PG_FREE_IF_COPY(key, 0);

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