Oracle 5.0, Reference Manual

Page: 506 / 3232

Server System Variables
486
Option Description
0
or
OFF
Do not cache results in or retrieve results from the query cache. Note that
this does not deallocate the query cache buffer. To do that, you should set
query_cache_size
[485] to 0.
1
or
ON
Cache all cacheable query results except for those that begin with
SELECT
SQL_NO_CACHE
.
2
or
DEMAND
Cache results only for cacheable queries that begin with
SELECT SQL_CACHE
.
This variable defaults to
ON
.
Any unique prefix of a valid value may be used to set the value of this variable.
•
query_cache_wlock_invalidate
[486]
Command-Line Format
--query_cache_wlock_invalidate
Option-File Format
query_cache_wlock_invalidate
Option Sets Variable Yes,
query_cache_wlock_invalidate
[486]
Variable Name
query_cache_wlock_invalidate
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type
boolean
Default
FALSE
Normally, when one client acquires a
WRITE
lock on a
MyISAM
table, other clients are not blocked
from issuing statements that read from the table if the query results are present in the query cache.
Setting this variable to 1 causes acquisition of a
WRITE
lock for a table to invalidate any queries in
the query cache that refer to the table. This forces other clients that attempt to access the table to
wait while the lock is in effect.
•
query_prealloc_size
[486]
Command-Line Format
--query_prealloc_size=#
Option-File Format
query_prealloc_size
Option Sets Variable Yes,
query_prealloc_size
[486]
Variable Name
query_prealloc_size
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Platform
Bit Size
32
Type
numeric
Default
8192
Range
8192 .. 4294967295
Block
Size
1024
Permitted Values