# name       : innodb_fast_checksum.patch
# introduced : 11 or before
# maintainer : Yasufumi
#
#!!! notice !!!
# Any small change to this file in the main branch
# should be done or reviewed by the maintainer!
--- a/storage/innobase/buf/buf0buf.c
+++ b/storage/innobase/buf/buf0buf.c
@@ -512,6 +512,27 @@
 	return(checksum);
 }
 
+UNIV_INTERN
+ulint
+buf_calc_page_new_checksum_32(
+/*==========================*/
+	const byte*	page)	/*!< in: buffer page */
+{
+	ulint checksum;
+
+	checksum = ut_fold_binary(page + FIL_PAGE_OFFSET,
+				  FIL_PAGE_FILE_FLUSH_LSN - FIL_PAGE_OFFSET)
+		+ ut_fold_binary(page + FIL_PAGE_DATA,
+				 FIL_PAGE_DATA_ALIGN_32 - FIL_PAGE_DATA)
+		+ ut_fold_binary_32(page + FIL_PAGE_DATA_ALIGN_32,
+				    UNIV_PAGE_SIZE - FIL_PAGE_DATA_ALIGN_32
+				    - FIL_PAGE_END_LSN_OLD_CHKSUM);
+
+	checksum = checksum & 0xFFFFFFFFUL;
+
+	return(checksum);
+}
+
 /********************************************************************//**
 In versions < 4.0.14 and < 4.1.1 there was a bug that the checksum only
 looked at the first few bytes of the page. This calculates that old
@@ -628,9 +649,21 @@
 		/* InnoDB versions < 4.0.14 and < 4.1.1 stored the space id
 		(always equal to 0), to FIL_PAGE_SPACE_OR_CHKSUM */
 
-		if (checksum_field != 0
+		if (!srv_fast_checksum
+		    && checksum_field != 0
+		    && checksum_field != BUF_NO_CHECKSUM_MAGIC
+		    && checksum_field
+		    != buf_calc_page_new_checksum(read_buf)) {
+
+			return(TRUE);
+		}
+
+		if (srv_fast_checksum
+		    && checksum_field != 0
 		    && checksum_field != BUF_NO_CHECKSUM_MAGIC
 		    && checksum_field
+		    != buf_calc_page_new_checksum_32(read_buf)
+		    && checksum_field
 		    != buf_calc_page_new_checksum(read_buf)) {
 
 			return(TRUE);
@@ -654,6 +687,7 @@
 	dict_index_t*	index;
 #endif /* !UNIV_HOTBACKUP */
 	ulint		checksum;
+	ulint		checksum_32;
 	ulint		old_checksum;
 	ulint		size	= zip_size;
 
@@ -740,12 +774,14 @@
 
 	checksum = srv_use_checksums
 		? buf_calc_page_new_checksum(read_buf) : BUF_NO_CHECKSUM_MAGIC;
+	checksum_32 = srv_use_checksums
+		? buf_calc_page_new_checksum_32(read_buf) : BUF_NO_CHECKSUM_MAGIC;
 	old_checksum = srv_use_checksums
 		? buf_calc_page_old_checksum(read_buf) : BUF_NO_CHECKSUM_MAGIC;
 
 	ut_print_timestamp(stderr);
 	fprintf(stderr,
-		"  InnoDB: Page checksum %lu, prior-to-4.0.14-form"
+		"  InnoDB: Page checksum %lu (32bit_calc: %lu), prior-to-4.0.14-form"
 		" checksum %lu\n"
 		"InnoDB: stored checksum %lu, prior-to-4.0.14-form"
 		" stored checksum %lu\n"
@@ -754,7 +790,7 @@
 		"InnoDB: Page number (if stored to page already) %lu,\n"
 		"InnoDB: space id (if created with >= MySQL-4.1.1"
 		" and stored already) %lu\n",
-		(ulong) checksum, (ulong) old_checksum,
+		(ulong) checksum, (ulong) checksum_32, (ulong) old_checksum,
 		(ulong) mach_read_from_4(read_buf + FIL_PAGE_SPACE_OR_CHKSUM),
 		(ulong) mach_read_from_4(read_buf + UNIV_PAGE_SIZE
 					 - FIL_PAGE_END_LSN_OLD_CHKSUM),
--- a/storage/innobase/buf/buf0flu.c
+++ b/storage/innobase/buf/buf0flu.c
@@ -1057,7 +1057,9 @@
 
 	mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM,
 			srv_use_checksums
-			? buf_calc_page_new_checksum(page)
+			? (!srv_fast_checksum
+			   ? buf_calc_page_new_checksum(page)
+			   : buf_calc_page_new_checksum_32(page))
 			: BUF_NO_CHECKSUM_MAGIC);
 
 	/* We overwrite the first 4 bytes of the end lsn field to store
--- a/storage/innobase/fil/fil0fil.c
+++ b/storage/innobase/fil/fil0fil.c
@@ -3103,13 +3103,24 @@
 		return(TRUE);
 	}
 
-	if (checksum_field != 0
+	if (!srv_fast_checksum
+	    && checksum_field != 0
 	    && checksum_field != BUF_NO_CHECKSUM_MAGIC
 	    && checksum_field
 	    != buf_calc_page_new_checksum(page)) {
 		return(TRUE);
 	}
 
+	if (srv_fast_checksum
+	    && checksum_field != 0
+	    && checksum_field != BUF_NO_CHECKSUM_MAGIC
+	    && checksum_field
+	    != buf_calc_page_new_checksum_32(page)
+	    && checksum_field
+	    != buf_calc_page_new_checksum(page)) {
+		return(TRUE);
+	}
+
 	return(FALSE);
 }
 
@@ -3125,7 +3136,9 @@
 	if (!zip_size) {
 		mach_write_to_4(page + FIL_PAGE_SPACE_OR_CHKSUM,
 				srv_use_checksums
-				? buf_calc_page_new_checksum(page)
+				? (!srv_fast_checksum
+				   ? buf_calc_page_new_checksum(page)
+				   : buf_calc_page_new_checksum_32(page))
 						: BUF_NO_CHECKSUM_MAGIC);
 		mach_write_to_4(page + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN_OLD_CHKSUM,
 				srv_use_checksums
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -183,6 +183,7 @@
 #endif /* UNIV_LOG_ARCHIVE */
 static my_bool	innobase_use_doublewrite		= TRUE;
 static my_bool	innobase_use_checksums			= TRUE;
+static my_bool	innobase_fast_checksum			= FALSE;
 static my_bool	innobase_recovery_stats			= TRUE;
 static my_bool	innobase_locks_unsafe_for_binlog	= FALSE;
 static my_bool	innobase_overwrite_relay_log_info	= FALSE;
@@ -2656,6 +2657,7 @@
 
 	srv_use_doublewrite_buf = (ibool) innobase_use_doublewrite;
 	srv_use_checksums = (ibool) innobase_use_checksums;
+	srv_fast_checksum = (ibool) innobase_fast_checksum;
 
 	srv_blocking_lru_restore = (ibool) innobase_blocking_lru_restore;
 
@@ -11541,6 +11543,15 @@
   "Disable with --skip-innodb-checksums.",
   NULL, NULL, TRUE);
 
+static MYSQL_SYSVAR_BOOL(fast_checksum, innobase_fast_checksum,
+  PLUGIN_VAR_NOCMDARG | PLUGIN_VAR_READONLY,
+  "Change the algorithm of checksum for the whole of datapage to 4-bytes word based. "
+  "The original checksum is checked after the new one. It may be slow for reading page"
+  " which has orginal checksum. Overwrite the page or recreate the InnoDB database, "
+  "if you want the entire benefit for performance at once. "
+  "#### Attention: The checksum is not compatible for normal or disabled version! ####",
+  NULL, NULL, FALSE);
+
 static MYSQL_SYSVAR_STR(data_home_dir, innobase_data_home_dir,
   PLUGIN_VAR_READONLY,
   "The common part for InnoDB table spaces.",
@@ -12112,6 +12123,7 @@
   MYSQL_SYSVAR(buffer_pool_size),
   MYSQL_SYSVAR(buffer_pool_instances),
   MYSQL_SYSVAR(checksums),
+  MYSQL_SYSVAR(fast_checksum),
   MYSQL_SYSVAR(commit_concurrency),
   MYSQL_SYSVAR(concurrency_tickets),
   MYSQL_SYSVAR(data_file_path),
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -621,6 +621,11 @@
 buf_calc_page_new_checksum(
 /*=======================*/
 	const byte*	page);	/*!< in: buffer page */
+UNIV_INTERN
+ulint
+buf_calc_page_new_checksum_32(
+/*==========================*/
+	const byte*	page);	/*!< in: buffer page */
 /********************************************************************//**
 In versions < 4.0.14 and < 4.1.1 there was a bug that the checksum only
 looked at the first few bytes of the page. This calculates that old
--- a/storage/innobase/include/fil0fil.h
+++ b/storage/innobase/include/fil0fil.h
@@ -119,6 +119,7 @@
 #define FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID  34 /*!< starting from 4.1.x this
 					contains the space id of the page */
 #define FIL_PAGE_DATA		38	/*!< start of the data on the page */
+#define FIL_PAGE_DATA_ALIGN_32	40
 /* @} */
 /** File page trailer @{ */
 #define FIL_PAGE_END_LSN_OLD_CHKSUM 8	/*!< the low 4 bytes of this are used
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -229,6 +229,7 @@
 
 extern ibool	srv_use_doublewrite_buf;
 extern ibool	srv_use_checksums;
+extern ibool	srv_fast_checksum;
 
 extern ulong	srv_max_buf_pool_modified_pct;
 extern ulong	srv_max_purge_lag;
--- a/storage/innobase/include/ut0rnd.h
+++ b/storage/innobase/include/ut0rnd.h
@@ -124,6 +124,13 @@
 	const byte*	str,	/*!< in: string of bytes */
 	ulint		len)	/*!< in: length */
 	__attribute__((pure));
+UNIV_INLINE
+ulint
+ut_fold_binary_32(
+/*==============*/
+	const byte*	str,	/*!< in: string of bytes */
+	ulint		len)	/*!< in: length */
+	__attribute__((pure));
 /***********************************************************//**
 Looks for a prime number slightly greater than the given argument.
 The prime is chosen so that it is not near any power of 2.
--- a/storage/innobase/include/ut0rnd.ic
+++ b/storage/innobase/include/ut0rnd.ic
@@ -226,3 +226,28 @@
 
 	return(fold);
 }
+
+UNIV_INLINE
+ulint
+ut_fold_binary_32(
+/*==============*/
+	const byte*	str,	/*!< in: string of bytes */
+	ulint		len)	/*!< in: length */
+{
+	const ib_uint32_t*	str_end = (const ib_uint32_t*) (str + len);
+	const ib_uint32_t*	str_32 = (const ib_uint32_t*) str;
+	ulint			fold = 0;
+
+	ut_ad(str);
+	/* This function is only for word-aligned data */
+	ut_ad(len % 4 == 0);
+	ut_ad((ulint)str % 4 == 0);
+
+	while (str_32 < str_end) {
+		fold = ut_fold_ulint_pair(fold, (ulint)(*str_32));
+
+		str_32++;
+	}
+
+	return(fold);
+}
--- a/storage/innobase/srv/srv0srv.c
+++ b/storage/innobase/srv/srv0srv.c
@@ -419,6 +419,7 @@
 
 UNIV_INTERN ibool	srv_use_doublewrite_buf	= TRUE;
 UNIV_INTERN ibool	srv_use_checksums = TRUE;
+UNIV_INTERN ibool	srv_fast_checksum = FALSE;
 
 UNIV_INTERN ulong	srv_replication_delay		= 0;
 
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/innodb_fast_checksum_basic.result
@@ -0,0 +1,3 @@
+SELECT @@global.innodb_fast_checksum;
+@@global.innodb_fast_checksum
+0
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/innodb_fast_checksum_basic.test
@@ -0,0 +1 @@
+SELECT @@global.innodb_fast_checksum;