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mariadb/mysql-test/suite/sys_vars/r/sysvars_innodb,32bit.rdiff
Marko Mäkelä bbd70fcc43 MDEV-23379 Deprecate&ignore InnoDB concurrency throttling parameters
The parameters innodb_thread_concurrency and innodb_commit_concurrency
were useful years ago when both computing resources and the implementation
of some shared data structures were limited. MySQL 5.0 or 5.1 had trouble
scaling beyond 8 concurrent connections. Most of the scalability bottlenecks
have been removed since then, and the transactions per second delivered
by MariaDB Server 10.5 should not dramatically drop upon exceeding the
'optimal' number of connections.

Hence, enabling any concurrency throttling for InnoDB actually makes
things worse. We have seen many customers mistakenly setting this to a
small value like 16 or 64 and then complaining the server was slow.

Ignoring the parameters allows us to remove some normally unused code
and data structures, which could slightly improve performance.

innodb_thread_concurrency, innodb_commit_concurrency,
innodb_replication_delay, innodb_concurrency_tickets,
innodb_thread_sleep_delay, innodb_adaptive_max_sleep_delay:
Deprecate and ignore; hard-wire to 0.

The column INFORMATION_SCHEMA.INNODB_TRX.trx_concurrency_tickets
will always report 0.
2020-08-04 06:59:29 +03:00

464 lines
15 KiB
Plaintext

--- sysvars_innodb.result
+++ sysvars_innodb,32bit.result
@@ -49,7 +49,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 8
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of InnoDB Adaptive Hash Index Partitions (default 8)
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 512
@@ -73,7 +73,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 64
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Data file autoextend increment in megabytes
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 1000
@@ -85,7 +85,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT
+VARIABLE_TYPE INT
VARIABLE_COMMENT The AUTOINC lock modes supported by InnoDB: 0 => Old style AUTOINC locking (for backward compatibility); 1 => New style AUTOINC locking; 2 => No AUTOINC locking (unsafe for SBR)
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 2
@@ -157,10 +157,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 134217728
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Size of a single memory chunk for resizing buffer pool. Online buffer pool resizing happens at this granularity. 0 means disable resizing buffer pool.
NUMERIC_MIN_VALUE 1048576
-NUMERIC_MAX_VALUE 9223372036854775807
+NUMERIC_MAX_VALUE 2147483647
NUMERIC_BLOCK_SIZE 1048576
ENUM_VALUE_LIST NULL
READ_ONLY YES
@@ -193,7 +193,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 25
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Dump only the hottest N% of each buffer pool, defaults to 25
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 100
@@ -229,7 +229,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Deprecated parameter with no effect.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 64
@@ -289,7 +289,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT A number between [0, 100] that tells how oftern buffer pool dump status in percentages should be printed. E.g. 10 means that buffer pool dump status is printed when every 10% of number of buffer pool pages are dumped. Default is 0 (only start and end status is printed).
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 100
@@ -421,7 +421,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 5
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT If the compression failure rate of a table is greater than this number more padding is added to the pages to reduce the failures. A value of zero implies no padding
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 100
@@ -445,7 +445,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 50
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Percentage of empty space on a data page that can be reserved to make the page compressible.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 75
@@ -661,7 +661,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 120
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of pages reserved in doublewrite buffer for batch flushing
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 127
@@ -757,7 +757,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 600
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Maximum number of seconds that semaphore times out in InnoDB.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 4294967295
@@ -805,7 +805,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Make the first page of the given tablespace dirty.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 4294967295
@@ -817,7 +817,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 30
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of iterations over which the background flushing is averaged.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 1000
@@ -841,7 +841,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Controls the durability/speed trade-off for commits. Set to 0 (write and flush redo log to disk only once per second), 1 (flush to disk at each commit), 2 (write to log at commit but flush to disk only once per second) or 3 (flush to disk at prepare and at commit, slower and usually redundant). 1 and 3 guarantees that after a crash, committed transactions will not be lost and will be consistent with the binlog and other transactional engines. 2 can get inconsistent and lose transactions if there is a power failure or kernel crash but not if mysqld crashes. 0 has no guarantees in case of crash. 0 and 2 can be faster than 1 or 3.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 3
@@ -865,7 +865,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Set to 0 (don't flush neighbors from buffer pool), 1 (flush contiguous neighbors from buffer pool) or 2 (flush neighbors from buffer pool), when flushing a block
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 2
@@ -913,7 +913,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Helps to save your data in case the disk image of the database becomes corrupt. Value 5 can return bogus data, and 6 can permanently corrupt data.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 6
@@ -937,7 +937,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 8000000
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search cache size in bytes
NUMERIC_MIN_VALUE 1600000
NUMERIC_MAX_VALUE 80000000
@@ -973,7 +973,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 84
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search maximum token size in characters
NUMERIC_MIN_VALUE 10
NUMERIC_MAX_VALUE 84
@@ -985,7 +985,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 3
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search minimum token size in characters
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 16
@@ -997,7 +997,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 2000
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search number of words to optimize for each optimize table call
NUMERIC_MIN_VALUE 1000
NUMERIC_MAX_VALUE 10000
@@ -1009,10 +1009,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 2000000000
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search query result cache limit in bytes
NUMERIC_MIN_VALUE 1000000
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
@@ -1033,7 +1033,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 2
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT InnoDB Fulltext search parallel sort degree, will round up to nearest power of 2 number
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 16
@@ -1045,7 +1045,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 640000000
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Total memory allocated for InnoDB Fulltext Search cache
NUMERIC_MIN_VALUE 32000000
NUMERIC_MAX_VALUE 1600000000
@@ -1069,7 +1069,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 100
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Up to what percentage of dirty pages should be flushed when innodb finds it has spare resources to do so.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 100
@@ -1105,22 +1105,22 @@
SESSION_VALUE NULL
DEFAULT_VALUE 200
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of IOPs the server can do. Tunes the background IO rate
NUMERIC_MIN_VALUE 100
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
COMMAND_LINE_ARGUMENT REQUIRED
VARIABLE_NAME INNODB_IO_CAPACITY_MAX
SESSION_VALUE NULL
-DEFAULT_VALUE 18446744073709551615
+DEFAULT_VALUE 4294967295
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Limit to which innodb_io_capacity can be inflated.
NUMERIC_MIN_VALUE 100
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
@@ -1165,7 +1165,7 @@
SESSION_VALUE 50
DEFAULT_VALUE 50
VARIABLE_SCOPE SESSION
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Timeout in seconds an InnoDB transaction may wait for a lock before being rolled back. Values above 100000000 disable the timeout.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 1073741824
@@ -1177,10 +1177,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 16777216
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT The size of the buffer which InnoDB uses to write log to the log files on disk.
NUMERIC_MIN_VALUE 262144
-NUMERIC_MAX_VALUE 9223372036854775807
+NUMERIC_MAX_VALUE 2147483647
NUMERIC_BLOCK_SIZE 1024
ENUM_VALUE_LIST NULL
READ_ONLY YES
@@ -1225,7 +1225,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Deprecated parameter with no effect.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 100
@@ -1273,7 +1273,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 8192
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Redo log write ahead unit size to avoid read-on-write, it should match the OS cache block IO size
NUMERIC_MIN_VALUE 512
NUMERIC_MAX_VALUE 16384
@@ -1285,10 +1285,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1024
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT How deep to scan LRU to keep it clean
NUMERIC_MIN_VALUE 100
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
@@ -1333,10 +1333,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Desired maximum length of the purge queue (0 = no limit)
NUMERIC_MIN_VALUE 0
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
@@ -1345,7 +1345,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Maximum delay of user threads in micro-seconds
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 10000000
@@ -1465,10 +1465,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT How many files at the maximum InnoDB keeps open at the same time.
NUMERIC_MIN_VALUE 0
-NUMERIC_MAX_VALUE 9223372036854775807
+NUMERIC_MAX_VALUE 2147483647
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY YES
@@ -1489,7 +1489,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Deprecated parameter with no effect.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 64
@@ -1513,7 +1513,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 16384
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Page size to use for all InnoDB tablespaces.
NUMERIC_MIN_VALUE 4096
NUMERIC_MAX_VALUE 65536
@@ -1549,7 +1549,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 300
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of UNDO log pages to purge in one batch from the history list.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 5000
@@ -1561,7 +1561,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 128
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Dictates rate at which UNDO records are purged. Value N means purge rollback segment(s) on every Nth iteration of purge invocation
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 128
@@ -1597,7 +1597,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 56
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of pages that must be accessed sequentially for InnoDB to trigger a readahead.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 64
@@ -1609,7 +1609,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 4
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of background read I/O threads in InnoDB.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 64
@@ -1657,7 +1657,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT An InnoDB page number.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 4294967295
@@ -1705,7 +1705,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1048576
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Memory buffer size for index creation
NUMERIC_MIN_VALUE 65536
NUMERIC_MAX_VALUE 67108864
@@ -1873,7 +1873,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 1
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Size of the mutex/lock wait array.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 1024
@@ -1897,10 +1897,10 @@
SESSION_VALUE NULL
DEFAULT_VALUE 30
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Count of spin-loop rounds in InnoDB mutexes (30 by default)
NUMERIC_MIN_VALUE 0
-NUMERIC_MAX_VALUE 18446744073709551615
+NUMERIC_MAX_VALUE 4294967295
NUMERIC_BLOCK_SIZE 0
ENUM_VALUE_LIST NULL
READ_ONLY NO
@@ -2005,7 +2005,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 128
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Deprecated parameter with no effect.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 128
@@ -2029,7 +2029,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 0
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of undo tablespaces to use.
NUMERIC_MIN_VALUE 0
NUMERIC_MAX_VALUE 127
@@ -2053,7 +2053,7 @@
SESSION_VALUE NULL
DEFAULT_VALUE 4
VARIABLE_SCOPE GLOBAL
-VARIABLE_TYPE BIGINT UNSIGNED
+VARIABLE_TYPE INT UNSIGNED
VARIABLE_COMMENT Number of background write I/O threads in InnoDB.
NUMERIC_MIN_VALUE 1
NUMERIC_MAX_VALUE 64