Command-Line Format | --group-concat-max-len=# |
---|---|
System Variable | group_concat_max_len
|
Scope | Global, Session |
Dynamic | Yes |
SET_VAR Hint Applies
|
Yes |
Type | Integer |
Default Value | 1024 |
Minimum Value | 4 |
Maximum Value (64-bit platforms) | 18446744073709551615 |
Maximum Value (32-bit platforms) | 4294967295 |
The maximum permitted result length in bytes for the
GROUP_CONCAT()
function. The
default is 1024.
YES
if the zlib
compression library is available to the server,
NO
if not. If not, the
COMPRESS()
and
UNCOMPRESS()
functions cannot
be used.
YES
if mysqld
supports
dynamic loading of plugins, NO
if not. If
the value is NO
, you cannot use options
such as --plugin-load
to load
plugins at server startup, or the INSTALL
PLUGIN
statement to load plugins at runtime.
YES
if the server supports spatial data
types, NO
if not.
This variable is a synonym for
have_ssl
.
As of MySQL 8.0.26,
have_openssl
is deprecated
and subject to removal in a future MySQL version. For
information about TLS properties of MySQL connection
interfaces, use the
tls_channel_status
table.
System variables that are true or false can be enabled at
server startup by naming them, or disabled by using a
--skip-
prefix. For example, to enable or
disable the InnoDB
adaptive hash index, you
can use
--innodb-adaptive-hash-index
or
--skip-innodb-adaptive-hash-index
on the command line, or
innodb_adaptive_hash_index
or
skip_innodb_adaptive_hash_index
in an
option file.
Command-Line Format | --innodb-buffer-pool-chunk-size=# |
---|---|
System Variable | innodb_buffer_pool_chunk_size
|
Scope | Global |
Dynamic | No |
SET_VAR Hint Applies
|
No |
Type | Integer |
Default Value | 134217728 |
Minimum Value | 1048576 |
Maximum Value | innodb_buffer_pool_size / innodb_buffer_pool_instances |
Unit | bytes |
innodb_buffer_pool_chunk_size
defines the chunk size for InnoDB
buffer
pool resizing operations.
To avoid copying all buffer pool pages during resizing
operations, the operation is performed in
“chunks”. By default,
innodb_buffer_pool_chunk_size
is 128MB (134217728 bytes). The number of pages contained in a
chunk depends on the value of
innodb_page_size
.
innodb_buffer_pool_chunk_size
can be increased or decreased in units of 1MB (1048576 bytes).
The following conditions apply when altering the
innodb_buffer_pool_chunk_size
value:
If
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
is larger than the current buffer pool size when the
buffer pool is initialized,
innodb_buffer_pool_chunk_size
is truncated to
innodb_buffer_pool_size
/
innodb_buffer_pool_instances
.
Buffer pool size must always be equal to or a multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
.
If you alter
innodb_buffer_pool_chunk_size
,
innodb_buffer_pool_size
is automatically rounded to a value that is equal to or a
multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
.
The adjustment occurs when the buffer pool is initialized.
Care should be taken when changing
innodb_buffer_pool_chunk_size
,
as changing this value can automatically increase the size
of the buffer pool. Before changing
innodb_buffer_pool_chunk_size
,
calculate its effect on
innodb_buffer_pool_size
to
ensure that the resulting buffer pool size is acceptable.
To avoid potential performance issues, the number of chunks
(innodb_buffer_pool_size
/
innodb_buffer_pool_chunk_size
)
should not exceed 1000.
The innodb_buffer_pool_size
variable is dynamic, which permits resizing the buffer pool
while the server is online. However, the buffer pool size must
be equal to or a multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
,
and changing either of those variable settings requires
restarting the server.
See Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” for more information.
Command-Line Format | --innodb-buffer-pool-chunk-size=# |
---|---|
System Variable | innodb_buffer_pool_chunk_size
|
Scope | Global |
Dynamic | No |
SET_VAR Hint Applies
|
No |
Type | Integer |
Default Value | 134217728 |
Minimum Value | 1048576 |
Maximum Value | innodb_buffer_pool_size / innodb_buffer_pool_instances |
Unit | bytes |
innodb_buffer_pool_chunk_size
defines the chunk size for InnoDB
buffer
pool resizing operations.
To avoid copying all buffer pool pages during resizing
operations, the operation is performed in
“chunks”. By default,
innodb_buffer_pool_chunk_size
is 128MB (134217728 bytes). The number of pages contained in a
chunk depends on the value of
innodb_page_size
.
innodb_buffer_pool_chunk_size
can be increased or decreased in units of 1MB (1048576 bytes).
The following conditions apply when altering the
innodb_buffer_pool_chunk_size
value:
If
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
is larger than the current buffer pool size when the
buffer pool is initialized,
innodb_buffer_pool_chunk_size
is truncated to
innodb_buffer_pool_size
/
innodb_buffer_pool_instances
.
Buffer pool size must always be equal to or a multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
.
If you alter
innodb_buffer_pool_chunk_size
,
innodb_buffer_pool_size
is automatically rounded to a value that is equal to or a
multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
.
The adjustment occurs when the buffer pool is initialized.
Care should be taken when changing
innodb_buffer_pool_chunk_size
,
as changing this value can automatically increase the size
of the buffer pool. Before changing
innodb_buffer_pool_chunk_size
,
calculate its effect on
innodb_buffer_pool_size
to
ensure that the resulting buffer pool size is acceptable.
To avoid potential performance issues, the number of chunks
(innodb_buffer_pool_size
/
innodb_buffer_pool_chunk_size
)
should not exceed 1000.
The innodb_buffer_pool_size
variable is dynamic, which permits resizing the buffer pool
while the server is online. However, the buffer pool size must
be equal to or a multiple of
innodb_buffer_pool_chunk_size
*
innodb_buffer_pool_instances
,
and changing either of those variable settings requires
restarting the server.
See Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” for more information.