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Comment:Better phrasing of the read-only WAL mode disadvantage in wal.html.
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SHA3-256: 729be21bb1b07146704483570369d876a981b96c1b75e6bf12540d110fe925c7
User & Date: drh 2018-05-22 15:40:13.557
Context
2018-05-23
18:06
Update the change log to mention the sqlite_sequence bug. (check-in: b31a1c8b32 user: drh tags: trunk)
2018-05-22
15:40
Better phrasing of the read-only WAL mode disadvantage in wal.html. (check-in: 729be21bb1 user: drh tags: trunk)
15:31
Read-only WAL mode in 3.22, not 3.20. (check-in: f5137e463c user: drh tags: trunk)
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    from a backup using the [backup API].  You must be in a rollback journal
    mode to change the page size.
<li><s>It is not possible to open [read-only WAL databases].
    The opening process must have write privileges for "<tt>-shm</tt>"
    [wal-index] shared memory file associated with the database, if that
    file exists, or else write access on the directory containing
    the database file if the "<tt>-shm</tt>" file does not exist.</s>
    Beginning with [version 3.22.0] ([dateof:3.22.0]) one can open a
    WAL mode database read-only as long as either the <tt>-shm</tt> file
    already exists or the <tt>-shm</tt> file can be created.
    Beginning with [version 3.22.0] ([dateof:3.22.0]), a read-only 
    WAL-mode database file can be opened if
    the <tt>-shm</tt> and <tt>-wal</tt> files
    already exists or those files can be created or the
    [immutable query parameter|database is immutable].
<li>WAL might be very slightly slower (perhaps 1% or 2% slower)
    than the traditional rollback-journal approach
    in applications that do mostly reads and seldom write.
<li>There is an additional quasi-persistent "<tt>-wal</tt>" file and
    "<tt>-shm</tt>" shared memory file associated with each
    database, which can make SQLite less appealing for use as an 
    [application file-format].
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