Oracle 5.0 Reference Manual page 508

The size of blocks that are allocated when doing range optimization.
•
read_buffer_size
Command-Line Format
Option-File Format
Option Sets Variable
Variable Name
Variable Scope
Dynamic Variable
Each thread that does a sequential scan allocates a buffer of this size (in bytes) for each table it
scans. If you do many sequential scans, you might want to increase this value, which defaults to
131072. The value of this variable should be a multiple of 4KB. If it is set to a value that is not a
multiple of 4KB, its value will be rounded down to the nearest multiple of 4KB.
The maximum permissible setting for
read_buffer_size
engine and apply in a general manner for optimization. See
Memory", for example.
• [488]
read_only
Command-Line Format
Option-File Format
Option Sets Variable
Variable Name
Variable Scope
Dynamic Variable
This variable is off by default. When it is enabled, the server permits no updates except from users
that have the
SUPER
threads. In replication setups, it can be useful to enable
ensure that slaves accept updates only from the master server and not from clients.
[488] does not apply to
read_only
not prevent the use of
to prevent changes to table structure or contents. Analysis and optimization do not qualify as such
changes. This means, for example, that consistency checks on read-only slaves can be performed
with
mysqlcheck --all-databases
Server System Variables
Block
1024
Size
[488]
--read_buffer_size=#
read_buffer_size
Yes,
read_buffer_size
read_buffer_size
Global, Session
Yes
Permitted Values
Type
numeric
Default
131072
Range
8200 .. 2147479552
read_buffer_size
[488] and
read_rnd_buffer_size
--read-only
read_only
Yes,
read_only
read_only
Global
Yes
Permitted Values
Type
boolean
Default
false
[578] privilege or (on a slave server) from updates performed by slave
TEMPORARY
or
ANALYZE TABLE OPTIMIZE TABLE
--analyze.
488
[488]
[488] is 2GB.
[489] are not specific to any storage
Section 8.9.4, "How MySQL Uses
[488]
read_only
tables as of MySQL 5.0.16. This variable does
statements because its purpose is
[488] on slave servers to