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Use elog(DEBUG4) for dynahash.c statistics output

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Previously this was being output to stderr.  This commit adjusts things
to use elog(DEBUG4).  Here we also adjust the format of the message to
add the hash table name and also put the message on a single line.  This
should make grepping the logs for this information easier.

Also get rid of the global hash table statistics.  This seems very dated
and didn't fit very well with trying to put all the statistics for a
specific hash table on a single log line.

The main aim here is to allow it so we can have at least one buildfarm
member build with HASH_STATISTICS to help prevent future changes from
breaking things in that area.  ca3891251 recently fixed some issues
here.

In passing, switch to using uint64 data types rather than longs for the
usage counters.  The long type is 32 bits on some platforms we support.

Author: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAApHDvoccvJ9CG5zx+i-EyCzJbcL5K=CzqrnL_YN59qaL5hiaw@mail.gmail.com
This commit is contained in:
David Rowley
2025-08-19 10:57:44 +12:00
parent 5e8f05cd70
commit 05fcb9667c
2 changed files with 14 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
src/backend/utils/hash/dynahash.c
View File

@@ -205,8 +205,9 @@ struct HASHHDR
* Count statistics here. NB: stats code doesn't bother with mutex, so
* counts could be corrupted a bit in a partitioned table.
*/
long accesses;
long collisions;
uint64 accesses;
uint64 collisions;
uint64 expansions;
#endif
};
@@ -266,12 +267,6 @@ struct HTAB
*/
#define MOD(x,y) ((x) & ((y)-1))
#ifdef HASH_STATISTICS
static long hash_accesses,
hash_collisions,
hash_expansions;
#endif
/*
* Private function prototypes
*/
@@ -661,7 +656,7 @@ hdefault(HTAB *hashp)
hctl->isfixed = false; /* can be enlarged */
#ifdef HASH_STATISTICS
hctl->accesses = hctl->collisions = 0;
hctl->accesses = hctl->collisions = hctl->expansions = 0;
#endif
}
@@ -888,7 +883,7 @@ hash_destroy(HTAB *hashp)
/* so this hashtable must have its own context */
Assert(hashp->hcxt != NULL);
hash_stats("destroy", hashp);
hash_stats(__func__, hashp);
/*
* Free everything by destroying the hash table's memory context.
@@ -898,19 +893,16 @@ hash_destroy(HTAB *hashp)
}
void
hash_stats(const char *where, HTAB *hashp)
hash_stats(const char *caller, HTAB *hashp)
{
#ifdef HASH_STATISTICS
fprintf(stderr, "%s: this HTAB -- accesses %ld collisions %ld\n",
where, hashp->hctl->accesses, hashp->hctl->collisions);
HASHHDR *hctl = hashp->hctl;
fprintf(stderr, "hash_stats: entries %ld keysize %ld maxp %u segmentcount %ld\n",
hash_get_num_entries(hashp), (long) hashp->hctl->keysize,
hashp->hctl->max_bucket, hashp->hctl->nsegs);
fprintf(stderr, "%s: total accesses %ld total collisions %ld\n",
where, hash_accesses, hash_collisions);
fprintf(stderr, "hash_stats: total expansions %ld\n",
hash_expansions);
elog(DEBUG4,
"hash_stats: Caller: %s Table Name: \"%s\" Accesses: " UINT64_FORMAT " Collisions: " UINT64_FORMAT " Expansions: " UINT64_FORMAT " Entries: %ld Key Size: %zu Max Bucket: %u Segment Count: %ld",
caller != NULL ? caller : "(unknown)", hashp->tabname, hctl->accesses,
hctl->collisions, hctl->expansions, hash_get_num_entries(hashp),
hctl->keysize, hctl->max_bucket, hctl->nsegs);
#endif
}
@@ -996,7 +988,6 @@ hash_search_with_hash_value(HTAB *hashp,
HashCompareFunc match;
#ifdef HASH_STATISTICS
hash_accesses++;
hctl->accesses++;
#endif
@@ -1040,7 +1031,6 @@ hash_search_with_hash_value(HTAB *hashp,
prevBucketPtr = &(currBucket->link);
currBucket = *prevBucketPtr;
#ifdef HASH_STATISTICS
hash_collisions++;
hctl->collisions++;
#endif
}
@@ -1176,7 +1166,6 @@ hash_update_hash_key(HTAB *hashp,
#ifdef HASH_STATISTICS
HASHHDR *hctl = hashp->hctl;
hash_accesses++;
hctl->accesses++;
#endif
@@ -1230,7 +1219,6 @@ hash_update_hash_key(HTAB *hashp,
prevBucketPtr = &(currBucket->link);
currBucket = *prevBucketPtr;
#ifdef HASH_STATISTICS
hash_collisions++;
hctl->collisions++;
#endif
}
@@ -1586,7 +1574,7 @@ expand_table(HTAB *hashp)
Assert(!IS_PARTITIONED(hctl));
#ifdef HASH_STATISTICS
hash_expansions++;
hctl->expansions++;
#endif
new_bucket = hctl->max_bucket + 1;

2
src/include/utils/hsearch.h
View File

@@ -132,7 +132,7 @@ typedef struct
extern HTAB *hash_create(const char *tabname, long nelem,
const HASHCTL *info, int flags);
extern void hash_destroy(HTAB *hashp);
extern void hash_stats(const char *where, HTAB *hashp);
extern void hash_stats(const char *caller, HTAB *hashp);
extern void *hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action,
bool *foundPtr);
extern uint32 get_hash_value(HTAB *hashp, const void *keyPtr);