Date: Mon, 18 Apr 2016 18:07:11 +0300
From: Aleksander Alekseev <a.alekseev@postgrespro.ru>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Should we remove unused code?
Message-ID: <20160418180711.55ac82c0@fujitsu>
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Hello

Today I've read this post:

http://blog.2ndquadrant.com/code-coverage/

I think its great and that everyone in this mailing list should
familiarize themselves with it.

Reading the coverage report, I discovered that some code is never
executed. Sometimes its OK (error reporting in out-of-memory cases),
sometimes its not (not enough tests). But there are also cases I'm not
sure about.

For instance there are two flags - HASH_SEGMENT and HASH_FFACTOR that
are in fact never used (see attachment). I wonder whether we should
keep code like this or not. 

What do you think?

-- 
Best regards,
Aleksander Alekseev
http://eax.me/

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diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
index 1a9f70c..9b32ceb 100644
--- a/src/backend/utils/hash/dynahash.c
+++ b/src/backend/utils/hash/dynahash.c
@@ -452,16 +452,6 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
 		hctl->num_partitions = info->num_partitions;
 	}
 
-	if (flags & HASH_SEGMENT)
-	{
-		hctl->ssize = info->ssize;
-		hctl->sshift = my_log2(info->ssize);
-		/* ssize had better be a power of 2 */
-		Assert(hctl->ssize == (1L << hctl->sshift));
-	}
-	if (flags & HASH_FFACTOR)
-		hctl->ffactor = info->ffactor;
-
 	/*
 	 * SHM hash tables have fixed directory size passed by the caller.
 	 */
diff --git a/src/include/utils/hsearch.h b/src/include/utils/hsearch.h
index 007ba2c..0646a72 100644
--- a/src/include/utils/hsearch.h
+++ b/src/include/utils/hsearch.h
@@ -81,9 +81,7 @@ typedef struct HASHCTL
 
 /* Flags to indicate which parameters are supplied */
 #define HASH_PARTITION	0x0001	/* Hashtable is used w/partitioned locking */
-#define HASH_SEGMENT	0x0002	/* Set segment size */
 #define HASH_DIRSIZE	0x0004	/* Set directory size (initial and max) */
-#define HASH_FFACTOR	0x0008	/* Set fill factor */
 #define HASH_ELEM		0x0010	/* Set keysize and entrysize */
 #define HASH_BLOBS		0x0020	/* Select support functions for binary keys */
 #define HASH_FUNCTION	0x0040	/* Set user defined hash function */

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