Bug 22988461 - INCORRECT CALCULATION FOR PAGES_HASHED, PAGES_OLD

The views:

   * innodb_buffer_stats_by_schema
   * innodb_buffer_stats_by_table

used COUNT(IF(...), 1, 0) to sum up the number of hashed and old pages.
However COUNT(0) will increment the counter, so the counts have been changed
to COUNT(IF(...), 1, NULL) as NULL will not increment the counter. This solution
is preferred over SUM(IF(...), 1, 0) as SUM returns a decimal instead of an
integer.

Also added test cases to ensure the percentage of old pages found is less
than @@global.innodb_old_blocks_pct as a check that not all pages are included
in the count.

mysql-test/suite/sysschema/r/v_innodb_buffer_stats_by_schema.result

@@ -18,3 +18,11 @@ pages_hashed	bigint(21)	NO		0
 pages_old	bigint(21)	NO		0	
 rows_cached	decimal(44,0)	NO		0	
 SELECT * FROM sys.x$innodb_buffer_stats_by_schema;
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+FROM sys.innodb_buffer_stats_by_schema;
+OldPagesSmallEnough
+1
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+FROM sys.x$innodb_buffer_stats_by_schema;
+OldPagesSmallEnough
+1

mysql-test/suite/sysschema/r/v_innodb_buffer_stats_by_table.result

@@ -20,3 +20,11 @@ pages_hashed	bigint(21)	NO		0
 pages_old	bigint(21)	NO		0	
 rows_cached	decimal(44,0)	NO		0	
 SELECT * FROM sys.x$innodb_buffer_stats_by_table;
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+FROM sys.innodb_buffer_stats_by_table;
+OldPagesSmallEnough
+1
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+FROM sys.x$innodb_buffer_stats_by_table;
+OldPagesSmallEnough
+1

mysql-test/suite/sysschema/t/v_innodb_buffer_stats_by_schema.test

@@ -20,3 +20,11 @@ DESC sys.x$innodb_buffer_stats_by_schema;
 SELECT * FROM sys.x$innodb_buffer_stats_by_schema;
 --enable_result_log
 
+
+# Check that the old pages percentage is smaller than @@global.innodb_old_blocks_pct
+# Add 3 percent to avoid false positives due to rounding errors
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+  FROM sys.innodb_buffer_stats_by_schema;
+
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+  FROM sys.x$innodb_buffer_stats_by_schema;

mysql-test/suite/sysschema/t/v_innodb_buffer_stats_by_table.test

@@ -20,3 +20,11 @@ DESC sys.x$innodb_buffer_stats_by_table;
 SELECT * FROM sys.x$innodb_buffer_stats_by_table;
 --enable_result_log
 
+
+# Check that the old pages percentage is smaller than @@global.innodb_old_blocks_pct
+# Add 3 percent to avoid false positives due to rounding errors
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+  FROM sys.innodb_buffer_stats_by_table;
+
+SELECT (SUM(pages_old)/sum(pages)*100 < (@@global.innodb_old_blocks_pct + 3)) AS OldPagesSmallEnough
+  FROM sys.x$innodb_buffer_stats_by_table;

views/i_s/innodb_buffer_stats_by_schema.sql

@@ -47,8 +47,8 @@ SELECT IF(LOCATE('.', ibp.table_name) = 0, 'InnoDB System', REPLACE(SUBSTRING_IN
        sys.format_bytes(SUM(IF(ibp.compressed_size = 0, 16384, compressed_size))) AS allocated,
        sys.format_bytes(SUM(ibp.data_size)) AS data,
        COUNT(ibp.page_number) AS pages,
-       COUNT(IF(ibp.is_hashed = 'YES', 1, 0)) AS pages_hashed,
-       COUNT(IF(ibp.is_old = 'YES', 1, 0)) AS pages_old,
+       COUNT(IF(ibp.is_hashed = 'YES', 1, NULL)) AS pages_hashed,
+       COUNT(IF(ibp.is_old = 'YES', 1, NULL)) AS pages_old,
        ROUND(SUM(ibp.number_records)/COUNT(DISTINCT ibp.index_name)) AS rows_cached 
   FROM information_schema.innodb_buffer_page ibp 
  WHERE table_name IS NOT NULL

views/i_s/innodb_buffer_stats_by_table.sql

@@ -53,8 +53,8 @@ SELECT IF(LOCATE('.', ibp.table_name) = 0, 'InnoDB System', REPLACE(SUBSTRING_IN
        sys.format_bytes(SUM(IF(ibp.compressed_size = 0, 16384, compressed_size))) AS allocated,
        sys.format_bytes(SUM(ibp.data_size)) AS data,
        COUNT(ibp.page_number) AS pages,
-       COUNT(IF(ibp.is_hashed = 'YES', 1, 0)) AS pages_hashed,
-       COUNT(IF(ibp.is_old = 'YES', 1, 0)) AS pages_old,
+       COUNT(IF(ibp.is_hashed = 'YES', 1, NULL)) AS pages_hashed,
+       COUNT(IF(ibp.is_old = 'YES', 1, NULL)) AS pages_old,
        ROUND(SUM(ibp.number_records)/COUNT(DISTINCT ibp.index_name)) AS rows_cached 
   FROM information_schema.innodb_buffer_page ibp 
  WHERE table_name IS NOT NULL

views/i_s/x_innodb_buffer_stats_by_schema.sql

@@ -46,8 +46,8 @@ SELECT IF(LOCATE('.', ibp.table_name) = 0, 'InnoDB System', REPLACE(SUBSTRING_IN
        SUM(IF(ibp.compressed_size = 0, 16384, compressed_size)) AS allocated,
        SUM(ibp.data_size) AS data,
        COUNT(ibp.page_number) AS pages,
-       COUNT(IF(ibp.is_hashed = 'YES', 1, 0)) AS pages_hashed,
-       COUNT(IF(ibp.is_old = 'YES', 1, 0)) AS pages_old,
+       COUNT(IF(ibp.is_hashed = 'YES', 1, NULL)) AS pages_hashed,
+       COUNT(IF(ibp.is_old = 'YES', 1, NULL)) AS pages_old,
        ROUND(IFNULL(SUM(ibp.number_records)/NULLIF(COUNT(DISTINCT ibp.index_name), 0), 0)) AS rows_cached 
   FROM information_schema.innodb_buffer_page ibp 
  WHERE table_name IS NOT NULL

views/i_s/x_innodb_buffer_stats_by_table.sql

@@ -53,8 +53,8 @@ SELECT IF(LOCATE('.', ibp.table_name) = 0, 'InnoDB System', REPLACE(SUBSTRING_IN
        SUM(IF(ibp.compressed_size = 0, 16384, compressed_size)) AS allocated,
        SUM(ibp.data_size) AS data,
        COUNT(ibp.page_number) AS pages,
-       COUNT(IF(ibp.is_hashed = 'YES', 1, 0)) AS pages_hashed,
-       COUNT(IF(ibp.is_old = 'YES', 1, 0)) AS pages_old,
+       COUNT(IF(ibp.is_hashed = 'YES', 1, NULL)) AS pages_hashed,
+       COUNT(IF(ibp.is_old = 'YES', 1, NULL)) AS pages_old,
        ROUND(IFNULL(SUM(ibp.number_records)/NULLIF(COUNT(DISTINCT ibp.index_name), 0), 0)) AS rows_cached 
   FROM information_schema.innodb_buffer_page ibp 
  WHERE table_name IS NOT NULL