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Commit3350b37

Browse files
author
Neil Conway
committed
This patch optimizes the md5_text() function (which is used to
implement the md5() SQL-level function). The old code did thefollowing:1. de-toast the datum2. convert it to a cstring via textout()3. get the length of the cstring via strlen()Since we are treating the datum context as a blob of binary data,the latter two steps are unnecessary. Once the data has beendetoasted, we can just use it as-is, and derive its length fromthe varlena metadata.This patch improves some run-of-the-mill md5() computations byjust under 10% in my limited tests, and passes the regression tests.I also noticed that md5_text() wasn't checking the return valueof md5_hash(); encountering OOM at precisely the right momentcould result in returning a random md5 hash. This patch correctsthat. A better fix would be to make md5_hash() only return onsuccess (and/or allocate via palloc()), but since it's used inthe frontend as well I don't see an easy way to do that.
1 parentb9a87e5 commit3350b37

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2 files changed

+13
-7
lines changed

2 files changed

+13
-7
lines changed

‎src/backend/libpq/md5.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*Portions Copyright (c) 1994, Regents of the University of California
1515
*
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* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/libpq/md5.c,v 1.27 2004/12/31 21:59:50 pgsql Exp $
17+
* $PostgreSQL: pgsql/src/backend/libpq/md5.c,v 1.28 2005/02/23 22:46:17 neilc Exp $
1818
*/
1919

2020

@@ -289,8 +289,8 @@ bytesToHex(uint8 b[16], char *s)
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* characters. you thus need to provide an array
290290
* of 33 characters, including the trailing '\0'.
291291
*
292-
*RETURNS0 on failure (out of memory for internal buffers) or
293-
*non-zero on success.
292+
*RETURNSfalse on failure (out of memory for internal buffers) or
293+
*true on success.
294294
*
295295
*STANDARDS MD5 is described in RFC 1321.
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*

‎src/backend/utils/adt/varlena.c

Lines changed: 10 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
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*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.118 2004/12/31 22:01:22 pgsql Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.119 2005/02/23 22:46:17 neilc Exp $
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*
1313
*-------------------------------------------------------------------------
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*/
@@ -2310,16 +2310,22 @@ to_hex64(PG_FUNCTION_ARGS)
23102310
Datum
23112311
md5_text(PG_FUNCTION_ARGS)
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{
2313-
char*buff=PG_TEXT_GET_STR(PG_GETARG_TEXT_P(0));
2314-
size_tlen=strlen(buff);
2313+
text*in_text=PG_GETARG_TEXT_P(0);
2314+
size_tlen;
23152315
char*hexsum;
23162316
text*result_text;
23172317

2318+
/* Calculate the length of the buffer using varlena metadata */
2319+
len=VARSIZE(in_text)-VARHDRSZ;
2320+
23182321
/* leave room for the terminating '\0' */
23192322
hexsum= (char*)palloc(MD5_HASH_LEN+1);
23202323

23212324
/* get the hash result */
2322-
md5_hash((void*)buff,len,hexsum);
2325+
if (md5_hash(VARDATA(in_text),len,hexsum)== false)
2326+
ereport(ERROR,
2327+
(errcode(ERRCODE_OUT_OF_MEMORY),
2328+
errmsg("out of memory")));
23232329

23242330
/* convert to text and return it */
23252331
result_text=PG_STR_GET_TEXT(hexsum);

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