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/*! @m_page{{c,java},readonly,Database read-only mode}
WiredTiger supports read-only mode databases. When a database is opened
in read-only mode, all modifications are disabled on the WT_CONNECTION
handle, any sessions opened in that connection and any cursors opened
in any of those sessions. For example, all cursor or session handle
methods that modify the database will instead return errors.
When a database is opened in read-only mode, the database directory and
content must already exist and have been shutdown cleanly.
@section readonly_config Database read-only configuration considerations
The \c readonly configuration affects other configuration settings.
Where a default setting contradicts read-only operation, WiredTiger
defaults are overridden to perform in a read-only mode. For example, LSM
tree merges are turned off when LSM trees are configured, and log file
archiving is disabled when logging is configured.
Where a user configured setting contradicts read-only operation, WiredTiger
will return an error. For example, zero-filling
log files is not allowed in read-only mode, and attempting to configure
them will return an error.
@section readonly_recovery Readonly configuration and recovery
Because recovery modifies the database, recovery cannot be done in
read-only mode. A ::wiredtiger_open call to open a database in read-only
mode will fail if the database was not cleanly shutdown and recovery is
required.
@section readonly_logging Readonly configuration and logging
If logging is enabled on the database when opened in read-only mode, log
file archiving and log file pre-allocation are disabled and the log files
will not be modified any way.
@section readonly_lsm Readonly configuration and LSM trees
If LSM trees are in use, read-only mode turns off all modification.
Internal LSM operations such as merging, creating new chunks, creating
bloom filters and dropping old chunks are disabled.
@section readonly_handles Readonly configuration and multiple database handles
One unusual affect of read-only operations is the potential for multiple
read-only database handles open on the same database at the same time.
WiredTiger prevents multiple connection handles by writing a lock file,
and this locking is done even in read-only mode. However, if the lock
file cannot be written, opening in read-only mode is still allowed to
proceed. For that reason, multiple read-only connection handles could
be open at the same time. Normal locking occurs if the lock file can be
written in read-only mode, preventing multiple database connections.
*/
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