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Swapped InnoDB and BDB in manual (InnoDB now mentioned first).

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Docs/manual.texi
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......@@ -815,15 +815,15 @@ We are still working on replication, so don't expect this to be rock
solid yet. On the other hand, some MySQL users are already
using this with good results.
@item InnoDB Tables -- Beta
This is a recent addition to @code{MySQL}. They appear to work well and
can be used after some initial testing.
@item BDB Tables -- Beta
The Berkeley DB code is very stable, but we are still improving the interface
between MySQL and BDB tables, so it will take some time before this
is tested as well as the other table types.
@item InnoDB Tables -- Beta
This is a recent addition to @code{MySQL}. They appear to work well and
can be used after some initial testing.
@item Automatic recovery of MyISAM tables - Beta
This only affects the new code that checks if the table was closed properly
on open and executes an automatic check/repair of the table if it wasn't.
......@@ -3802,8 +3802,8 @@ concerned about transactions. For them transactions are not an
issue. For those of our users who are concerned with or have wondered
about transactions vis-a-vis MySQL, there is a ``MySQL
way'' as we have outlined above. For those where safety is more
important than speed, we recommend them to use the @code{BDB},
or @code{InnoDB} tables for all their critical data. @xref{Table types}.
important than speed, we recommend them to use the @code{InnoDB},
or @code{BDB} tables for all their critical data. @xref{Table types}.
One final note: We are currently working on a safe replication schema
that we believe to be better than any commercial replication system we
......@@ -3881,7 +3881,7 @@ and may be retrieved by @code{mysqldump} and ODBC. At a later stage we will
implement the foreign key constraints for application that can't easily be
coded to avoid them.
MySQL 3.23.44 and forwards, InnoDB tables supports checking of foreign
In MySQL 3.23.44 and up, InnoDB tables supports checking of foreign
key constraints. @xref{InnoDB}.
@menu
......@@ -4055,12 +4055,12 @@ Entry level SQL92. ODBC levels 0-2.
@cindex transaction-safe tables
@cindex tables, updating
@cindex updating, tables
@cindex @code{BDB} tables
@cindex @code{InnoDB} tables
@cindex @code{BDB} tables
The following mostly applies only for @code{ISAM}, @code{MyISAM}, and
@code{HEAP} tables. If you only use transaction-safe tables (@code{BDB},
or @code{InnoDB} tables) in an an update, you can do
@code{HEAP} tables. If you only use transaction-safe tables (@code{InnoDB},
or @code{BDB} tables) in an an update, you can do
@code{COMMIT} and @code{ROLLBACK} also with MySQL.
@xref{COMMIT}.
......@@ -5152,7 +5152,7 @@ tables or disk based @code{MyISAM}. @xref{Table types}.
@item
MySQL has support for two different table handlers that support
transactions, @code{BerkeleyDB} and @code{InnoDB}. Because every
transactions, @code{InnoDB} and @code{BerkeleyDB}. Because every
transaction engine performs differently under different conditions, this
gives the application writer more options to find an optimal solution for
his or her setup. @xref{Table types}.
......@@ -6229,7 +6229,7 @@ Here is a list of the different MySQL servers you can use:
@multitable @columnfractions .25 .75
@item @code{mysqld} @tab
Compiled with full debugging and automatic memory allocation checking,
symbolic links, BDB and InnoDB tables.
symbolic links, InnoDB and BDB tables.
@item @code{mysqld-opt} @tab
Optimized binary with no support for transactional tables.
@item @code{mysqld-nt} @tab
......@@ -6237,7 +6237,7 @@ Optimized binary for NT with support for named pipes. You can run this
version on Win98, but in this case no named pipes are created and you must
have TCP/IP installed.
@item @code{mysqld-max} @tab
Optimized binary with support for symbolic links, BDB and InnoDB tables.
Optimized binary with support for symbolic links, InnoDB and BDB tables.
@item @code{mysqld-max-nt} @tab
Like @code{mysqld-max}, but compiled with support for named pipes.
@end multitable
......@@ -7332,8 +7332,8 @@ NOT in the standard binary distributions. Here is a list of the most
common extra options that you may want to use:
@itemize @bullet
@item @code{--with-berkeley-db}
@item @code{--with-innodb}
@item @code{--with-berkeley-db}
@item @code{--with-raid}
@item @code{--with-libwrap}
@item @code{--with-named-z-lib (This is done for some of the binaries)}
......@@ -9198,7 +9198,7 @@ reload the grant tables.
@cindex server, starting problems
@cindex problems, starting the server
If you are going to use tables that support transactions (BDB, InnoDB),
If you are going to use tables that support transactions (InnoDB, BDB),
you should first create a my.cnf file and set startup options
for the table types you plan to use. @xref{Table types}.
......@@ -12099,7 +12099,7 @@ following is reported to work
CC=cc CXX=CC CFLAGS='-O3 -n32 -TARG:platform=IP22 -I/usr/local/include \
-L/usr/local/lib' CXXFLAGS='-O3 -n32 -TARG:platform=IP22 \
-I/usr/local/include -L/usr/local/lib' ./configure --prefix=/usr/local/mysql \
--with-berkeley-db --with-innodb \
--with-innodb --with-berkeley-db \
--with-libwrap=/usr/local --with-named-curses-libs=/usr/local/lib/libncurses.a
@end example
......@@ -20720,12 +20720,12 @@ fast. It applies only to index recreation during @code{REPAIR},
@code{CREATE INDEX}, or @code{ALTER TABLE}.
@item @code{have_bdb}
@code{YES} if @code{mysqld} supports Berkeley DB tables. @code{DISABLED}
if @code{--skip-bdb} is used.
@item @code{have_innodb}
@code{YES} if @code{mysqld} supports InnoDB tables. @code{DISABLED}
if @code{--skip-innodb} is used.
@item @code{have_bdb}
@code{YES} if @code{mysqld} supports Berkeley DB tables. @code{DISABLED}
if @code{--skip-bdb} is used.
@item @code{have_raid}
@code{YES} if @code{mysqld} supports the @code{RAID} option.
@item @code{have_openssl}
......@@ -22371,8 +22371,8 @@ the following configure options:
@multitable @columnfractions .3 .7
@item @strong{Option} @tab @strong{Comment}
@item --with-server-suffix=-max @tab Add a suffix to the @code{mysqld} version string.
@item --with-bdb @tab Support for Berkeley DB (BDB) tables
@item --with-innodb @tab Support for InnoDB tables.
@item --with-bdb @tab Support for Berkeley DB (BDB) tables
@item CFLAGS=-DUSE_SYMDIR @tab Symbolic links support for Windows.
@end multitable
......@@ -22384,7 +22384,7 @@ standard @code{mysqld.exe} binary and the @code{mysqld-max.exe} binary.
@uref{http://www.mysql.com/downloads/mysql-3.23.html}.
@xref{Windows installation}.
Note that as Berkeley DB and InnoDB are not available for all platforms,
Note that as InnoDB and Berkeley DB are not available for all platforms,
some of the @code{Max} binaries may not have support for both of these.
You can check which table types are supported by doing the following
query:
......@@ -26660,7 +26660,7 @@ high lock speed. For large tables, table locking is MUCH better than
row locking for most applications, but there are, of course, some
pitfalls.
For @code{BDB} and @code{InnoDB} tables, MySQL only uses table
For @code{InnoDB} and @code{BDB} tables, MySQL only uses table
locking if you explicitely lock the table with @code{LOCK TABLES} or
execute a command that will modify every row in the table, like
@code{ALTER TABLE}. For these table types we recommend you to not use
......@@ -35861,8 +35861,8 @@ By default, MySQL runs in @code{autocommit} mode. This means that
as soon as you execute an update, MySQL will store the update on
disk.
If you are using transactions safe tables (like @code{BDB},
@code{InnoDB}, you can put MySQL into
If you are using transactions safe tables (like @code{InnoDB},
@code{BDB}, you can put MySQL into
non-@code{autocommit} mode with the following command:
@example
......@@ -36344,8 +36344,8 @@ parameters to @code{FULLTEXT} in @code{CREATE/ALTER TABLE}).
As of MySQL Version 3.23.6, you can choose between three basic
table formats (@code{ISAM}, @code{HEAP} and @code{MyISAM}. Newer
MySQL may support additional table type (@code{BDB},
or @code{InnoDB}), depending on how you compile it.
MySQL may support additional table type (@code{InnoDB},
or @code{BDB}), depending on how you compile it.
When you create a new table, you can tell MySQL which table
type it should use for the table. MySQL will always create a
......@@ -36370,7 +36370,7 @@ You can convert tables between different types with the @code{ALTER
TABLE} statement. @xref{ALTER TABLE, , @code{ALTER TABLE}}.
Note that MySQL supports two different kinds of
tables: transaction-safe tables (@code{BDB} and @code{InnoDB})
tables: transaction-safe tables (@code{InnoDB} and @code{BDB})
and not transaction-safe tables (@code{HEAP}, @code{ISAM},
@code{MERGE}, and @code{MyISAM}).
......@@ -36411,8 +36411,8 @@ of both worlds.
* MERGE:: MERGE tables
* ISAM:: ISAM tables
* HEAP:: HEAP tables
* BDB:: BDB or Berkeley_db tables
* InnoDB:: InnoDB tables
* BDB:: BDB or Berkeley_db tables
@end menu
......@@ -37122,7 +37122,7 @@ mysql> ALTER TABLE tbl_name TYPE = MYISAM;
@end example
@node HEAP, BDB, ISAM, Table types
@node HEAP, InnoDB, ISAM, Table types
@section HEAP Tables
@cindex tables, @code{HEAP}
......@@ -37202,302 +37202,7 @@ SUM_OVER_ALL_KEYS(max_length_of_key + sizeof(char*) * 2)
@code{sizeof(char*)} is 4 on 32-bit machines and 8 on 64-bit machines.
@node BDB, InnoDB, HEAP, Table types
@section BDB or Berkeley_DB Tables
@cindex tables, @code{BDB}
@cindex tables, @code{Berkeley DB}
@menu
* BDB overview:: Overview of BDB Tables
* BDB install:: Installing BDB
* BDB start:: BDB startup options
* BDB characteristic:: Some characteristic of @code{BDB} tables:
* BDB TODO:: Some things we need to fix for BDB in the near future:
* BDB portability:: Operating systems supported by @strong{BDB}
* BDB errors:: Errors You May Get When Using BDB Tables
@end menu
@node BDB overview, BDB install, BDB, BDB
@subsection Overview of BDB Tables
Support for BDB tables is included in the MySQL source distribution
starting from Version 3.23.34 and is activated in the MySQL-Max
binary.
BerkeleyDB, available at @uref{http://www.sleepycat.com/} has provided
MySQL with a transactional table handler. By using BerkeleyDB
tables, your tables may have a greater chance of surviving crashes, and also
provides @code{COMMIT} and @code{ROLLBACK} on transactions. The
MySQL source distribution comes with a BDB distribution that has a
couple of small patches to make it work more smoothly with MySQL.
You can't use a non-patched @code{BDB} version with MySQL.
We at MySQL AB are working in close cooperation with Sleepycat to
keep the quality of the MySQL/BDB interface high.
When it comes to supporting BDB tables, we are committed to help our
users to locate the problem and help creating a reproducable test case
for any problems involving BDB tables. Any such test case will be
forwarded to Sleepycat who in turn will help us find and fix the
problem. As this is a two stage operation, any problems with BDB tables
may take a little longer for us to fix than for other table handlers.
However, as the BerkeleyDB code itself has been used by many other
applications than MySQL, we don't envision any big problems with
this. @xref{Support}.
@node BDB install, BDB start, BDB overview, BDB
@subsection Installing BDB
If you have downloaded a binary version of MySQL that includes
support for BerkeleyDB, simply follow the instructions for installing a
binary version of MySQL.
@xref{Installing binary}. @xref{mysqld-max, , @code{mysqld-max}}.
To compile MySQL with Berkeley DB support, download MySQL
Version 3.23.34 or newer and configure @code{MySQL} with the
@code{--with-berkeley-db} option. @xref{Installing source}.
@example
cd /path/to/source/of/mysql-3.23.34
./configure --with-berkeley-db
@end example
Please refer to the manual provided with the @code{BDB} distribution for
more updated information.
Even though Berkeley DB is in itself very tested and reliable,
the MySQL interface is still considered beta quality.
We are actively improving and optimizing it to get it stable very
soon.
@node BDB start, BDB characteristic, BDB install, BDB
@subsection BDB startup options
If you are running with @code{AUTOCOMMIT=0} then your changes in @code{BDB}
tables will not be updated until you execute @code{COMMIT}. Instead of commit
you can execute @code{ROLLBACK} to forget your changes. @xref{COMMIT}.
If you are running with @code{AUTOCOMMIT=1} (the default), your changes
will be committed immediately. You can start an extended transaction with
the @code{BEGIN WORK} SQL command, after which your changes will not be
committed until you execute @code{COMMIT} (or decide to @code{ROLLBACK}
the changes).
The following options to @code{mysqld} can be used to change the behavior of
BDB tables:
@multitable @columnfractions .30 .70
@item @strong{Option} @tab @strong{Meaning}
@item @code{--bdb-home=directory} @tab Base directory for BDB tables. This should be the same directory you use for --datadir.
@item @code{--bdb-lock-detect=#} @tab Berkeley lock detect. One of (DEFAULT, OLDEST, RANDOM, or YOUNGEST).
@item @code{--bdb-logdir=directory} @tab Berkeley DB log file directory.
@item @code{--bdb-no-sync} @tab Don't synchronously flush logs.
@item @code{--bdb-no-recover} @tab Don't start Berkeley DB in recover mode.
@item @code{--bdb-shared-data} @tab Start Berkeley DB in multi-process mode (Don't use @code{DB_PRIVATE} when initializing Berkeley DB)
@item @code{--bdb-tmpdir=directory} @tab Berkeley DB tempfile name.
@item @code{--skip-bdb} @tab Don't use berkeley db.
@item @code{-O bdb_max_lock=1000} @tab Set the maximum number of locks possible. @xref{SHOW VARIABLES}.
@end multitable
If you use @code{--skip-bdb}, MySQL will not initialize the
Berkeley DB library and this will save a lot of memory. Of course,
you cannot use @code{BDB} tables if you are using this option.
Normally you should start @code{mysqld} without @code{--bdb-no-recover} if you
intend to use BDB tables. This may, however, give you problems when you
try to start @code{mysqld} if the BDB log files are corrupted. @xref{Starting
server}.
With @code{bdb_max_lock} you can specify the maximum number of locks
(10000 by default) you can have active on a BDB table. You should
increase this if you get errors of type @code{bdb: Lock table is out of
available locks} or @code{Got error 12 from ...} when you have do long
transactions or when @code{mysqld} has to examine a lot of rows to
calculate the query.
You may also want to change @code{binlog_cache_size} and
@code{max_binlog_cache_size} if you are using big multi-line transactions.
@xref{COMMIT}.
@node BDB characteristic, BDB TODO, BDB start, BDB
@subsection Some characteristic of @code{BDB} tables:
@itemize @bullet
@item
To be able to rollback transactions BDB maintain log files. For maximum
performance you should place these on another disk than your databases
by using the @code{--bdb_log_dir} options.
@item
MySQL performs a checkpoint each time a new BDB log
file is started, and removes any log files that are not needed for
current transactions. One can also run @code{FLUSH LOGS} at any time
to checkpoint the Berkeley DB tables.
For disaster recovery, one should use table backups plus
MySQL's binary log. @xref{Backup}.
@strong{Warning}: If you delete old log files that are in use, BDB will
not be able to do recovery at all and you may lose data if something
goes wrong.
@item
MySQL requires a @code{PRIMARY KEY} in each BDB table to be
able to refer to previously read rows. If you don't create one,
MySQL will create an maintain a hidden @code{PRIMARY KEY} for
you. The hidden key has a length of 5 bytes and is incremented for each
insert attempt.
@item
If all columns you access in a @code{BDB} table are part of the same index or
part of the primary key, then MySQL can execute the query
without having to access the actual row. In a @code{MyISAM} table the
above holds only if the columns are part of the same index.
@item
The @code{PRIMARY KEY} will be faster than any other key, as the
@code{PRIMARY KEY} is stored together with the row data. As the other keys are
stored as the key data + the @code{PRIMARY KEY}, it's important to keep the
@code{PRIMARY KEY} as short as possible to save disk and get better speed.
@item
@code{LOCK TABLES} works on @code{BDB} tables as with other tables. If
you don't use @code{LOCK TABLE}, MYSQL will issue an internal
multiple-write lock on the table to ensure that the table will be
properly locked if another thread issues a table lock.
@item
Internal locking in @code{BDB} tables is done on page level.
@item
@code{SELECT COUNT(*) FROM table_name} is slow as @code{BDB} tables doesn't
maintain a count of the number of rows in the table.
@item
Scanning is slower than with @code{MyISAM} tables as one has data in BDB
tables stored in B-trees and not in a separate data file.
@item
The application must always be prepared to handle cases where
any change of a @code{BDB} table may make an automatic rollback and any
read may fail with a deadlock error.
@item
Keys are not compressed to previous keys as with ISAM or MyISAM
tables. In other words, the key information will take a little more
space in @code{BDB} tables compared to MyISAM tables which don't use
@code{PACK_KEYS=0}.
@item
There is often holes in the BDB table to allow you to insert new rows in
the middle of the key tree. This makes BDB tables somewhat larger than
MyISAM tables.
@item
The optimizer needs to know an approximation of the number of rows in
the table. MySQL solves this by counting inserts and
maintaining this in a separate segment in each BDB table. If you don't
do a lot of @code{DELETE} or @code{ROLLBACK}:s this number should be
accurate enough for the MySQL optimizer, but as MySQL
only store the number on close, it may be wrong if MySQL dies
unexpectedly. It should not be fatal even if this number is not 100 %
correct. One can update the number of rows by executing @code{ANALYZE
TABLE} or @code{OPTIMIZE TABLE}. @xref{ANALYZE TABLE} . @xref{OPTIMIZE
TABLE}.
@item
If you get full disk with a @code{BDB} table, you will get an error
(probably error 28) and the transaction should roll back. This is in
contrast with @code{MyISAM} and @code{ISAM} tables where @code{mysqld} will
wait for enough free disk before continuing.
@end itemize
@node BDB TODO, BDB portability, BDB characteristic, BDB
@subsection Some things we need to fix for BDB in the near future:
@itemize @bullet
@item
It's very slow to open many BDB tables at the same time. If you are
going to use BDB tables, you should not have a very big table cache (>
256 ?) and you should use @code{--no-auto-rehash} with the @code{mysql}
client. We plan to partly fix this in 4.0.
@item
@code{SHOW TABLE STATUS} doesn't yet provide that much information for BDB
tables.
@item
Optimize performance.
@item
Change to not use page locks at all when we are scanning tables.
@end itemize
@node BDB portability, BDB errors, BDB TODO, BDB
@subsection Operating systems supported by @strong{BDB}
If you after having built MySQL with support for BDB tables get
the following error in the log file when you start @code{mysqld}:
@example
bdb: architecture lacks fast mutexes: applications cannot be threaded
Can't init dtabases
@end example
This means that @code{BDB} tables are not supported for your architecture.
In this case you have to rebuild MySQL without BDB table support.
NOTE: The following list is not complete; We will update this as we get
more information about this.
Currently we know that BDB tables works with the following operating
system.
@itemize @bullet
@item
Linux 2.x intel
@item
Solaris sparc
@item
SCO OpenServer
@item
SCO UnixWare 7.0.1
@end itemize
It doesn't work with the following operating systems:
@itemize @bullet
@item
Linux 2.x Alpha
@item
Max OS X
@end itemize
@node BDB errors, , BDB portability, BDB
@subsection Errors You May Get When Using BDB Tables
@itemize @bullet
@item
If you get the following error in the @code{hostname.err log} when
starting @code{mysqld}:
@example
bdb: Ignoring log file: .../log.XXXXXXXXXX: unsupported log version #
@end example
it means that the new @code{BDB} version doesn't support the old log
file format. In this case you have to delete all @code{BDB} log BDB
from your database directory (the files that has the format
@code{log.XXXXXXXXXX} ) and restart @code{mysqld}. We would also
recommend you to do a @code{mysqldump --opt} of your old @code{BDB}
tables, delete the old table and restore the dump.
@item
If you are running in not @code{auto_commit} mode and delete a table you
are using by another thread you may get the following error messages in
the MySQL error file:
@example
001119 23:43:56 bdb: Missing log fileid entry
001119 23:43:56 bdb: txn_abort: Log undo failed for LSN: 1 3644744: Invalid
@end example
This is not fatal but we don't recommend that you delete tables if you are
not in @code{auto_commit} mode, until this problem is fixed (the fix is
not trivial).
@end itemize
@node InnoDB, , BDB, Table types
@node InnoDB, BDB, HEAP, Table types
@section InnoDB Tables
@menu
......@@ -39055,6 +38760,301 @@ Finland
@end example
@node BDB, , InnoDB, Table types
@section BDB or Berkeley_DB Tables
@cindex tables, @code{BDB}
@cindex tables, @code{Berkeley DB}
@menu
* BDB overview:: Overview of BDB Tables
* BDB install:: Installing BDB
* BDB start:: BDB startup options
* BDB characteristic:: Some characteristic of @code{BDB} tables:
* BDB TODO:: Some things we need to fix for BDB in the near future:
* BDB portability:: Operating systems supported by @strong{BDB}
* BDB errors:: Errors You May Get When Using BDB Tables
@end menu
@node BDB overview, BDB install, BDB, BDB
@subsection Overview of BDB Tables
Support for BDB tables is included in the MySQL source distribution
starting from Version 3.23.34 and is activated in the MySQL-Max
binary.
BerkeleyDB, available at @uref{http://www.sleepycat.com/} has provided
MySQL with a transactional table handler. By using BerkeleyDB
tables, your tables may have a greater chance of surviving crashes, and also
provides @code{COMMIT} and @code{ROLLBACK} on transactions. The
MySQL source distribution comes with a BDB distribution that has a
couple of small patches to make it work more smoothly with MySQL.
You can't use a non-patched @code{BDB} version with MySQL.
We at MySQL AB are working in close cooperation with Sleepycat to
keep the quality of the MySQL/BDB interface high.
When it comes to supporting BDB tables, we are committed to help our
users to locate the problem and help creating a reproducable test case
for any problems involving BDB tables. Any such test case will be
forwarded to Sleepycat who in turn will help us find and fix the
problem. As this is a two stage operation, any problems with BDB tables
may take a little longer for us to fix than for other table handlers.
However, as the BerkeleyDB code itself has been used by many other
applications than MySQL, we don't envision any big problems with
this. @xref{Support}.
@node BDB install, BDB start, BDB overview, BDB
@subsection Installing BDB
If you have downloaded a binary version of MySQL that includes
support for BerkeleyDB, simply follow the instructions for installing a
binary version of MySQL.
@xref{Installing binary}. @xref{mysqld-max, , @code{mysqld-max}}.
To compile MySQL with Berkeley DB support, download MySQL
Version 3.23.34 or newer and configure @code{MySQL} with the
@code{--with-berkeley-db} option. @xref{Installing source}.
@example
cd /path/to/source/of/mysql-3.23.34
./configure --with-berkeley-db
@end example
Please refer to the manual provided with the @code{BDB} distribution for
more updated information.
Even though Berkeley DB is in itself very tested and reliable,
the MySQL interface is still considered beta quality.
We are actively improving and optimizing it to get it stable very
soon.
@node BDB start, BDB characteristic, BDB install, BDB
@subsection BDB startup options
If you are running with @code{AUTOCOMMIT=0} then your changes in @code{BDB}
tables will not be updated until you execute @code{COMMIT}. Instead of commit
you can execute @code{ROLLBACK} to forget your changes. @xref{COMMIT}.
If you are running with @code{AUTOCOMMIT=1} (the default), your changes
will be committed immediately. You can start an extended transaction with
the @code{BEGIN WORK} SQL command, after which your changes will not be
committed until you execute @code{COMMIT} (or decide to @code{ROLLBACK}
the changes).
The following options to @code{mysqld} can be used to change the behavior of
BDB tables:
@multitable @columnfractions .30 .70
@item @strong{Option} @tab @strong{Meaning}
@item @code{--bdb-home=directory} @tab Base directory for BDB tables. This should be the same directory you use for --datadir.
@item @code{--bdb-lock-detect=#} @tab Berkeley lock detect. One of (DEFAULT, OLDEST, RANDOM, or YOUNGEST).
@item @code{--bdb-logdir=directory} @tab Berkeley DB log file directory.
@item @code{--bdb-no-sync} @tab Don't synchronously flush logs.
@item @code{--bdb-no-recover} @tab Don't start Berkeley DB in recover mode.
@item @code{--bdb-shared-data} @tab Start Berkeley DB in multi-process mode (Don't use @code{DB_PRIVATE} when initializing Berkeley DB)
@item @code{--bdb-tmpdir=directory} @tab Berkeley DB tempfile name.
@item @code{--skip-bdb} @tab Don't use berkeley db.
@item @code{-O bdb_max_lock=1000} @tab Set the maximum number of locks possible. @xref{SHOW VARIABLES}.
@end multitable
If you use @code{--skip-bdb}, MySQL will not initialize the
Berkeley DB library and this will save a lot of memory. Of course,
you cannot use @code{BDB} tables if you are using this option.
Normally you should start @code{mysqld} without @code{--bdb-no-recover} if you
intend to use BDB tables. This may, however, give you problems when you
try to start @code{mysqld} if the BDB log files are corrupted. @xref{Starting
server}.
With @code{bdb_max_lock} you can specify the maximum number of locks
(10000 by default) you can have active on a BDB table. You should
increase this if you get errors of type @code{bdb: Lock table is out of
available locks} or @code{Got error 12 from ...} when you have do long
transactions or when @code{mysqld} has to examine a lot of rows to
calculate the query.
You may also want to change @code{binlog_cache_size} and
@code{max_binlog_cache_size} if you are using big multi-line transactions.
@xref{COMMIT}.
@node BDB characteristic, BDB TODO, BDB start, BDB
@subsection Some characteristic of @code{BDB} tables:
@itemize @bullet
@item
To be able to rollback transactions BDB maintain log files. For maximum
performance you should place these on another disk than your databases
by using the @code{--bdb_log_dir} options.
@item
MySQL performs a checkpoint each time a new BDB log
file is started, and removes any log files that are not needed for
current transactions. One can also run @code{FLUSH LOGS} at any time
to checkpoint the Berkeley DB tables.
For disaster recovery, one should use table backups plus
MySQL's binary log. @xref{Backup}.
@strong{Warning}: If you delete old log files that are in use, BDB will
not be able to do recovery at all and you may lose data if something
goes wrong.
@item
MySQL requires a @code{PRIMARY KEY} in each BDB table to be
able to refer to previously read rows. If you don't create one,
MySQL will create an maintain a hidden @code{PRIMARY KEY} for
you. The hidden key has a length of 5 bytes and is incremented for each
insert attempt.
@item
If all columns you access in a @code{BDB} table are part of the same index or
part of the primary key, then MySQL can execute the query
without having to access the actual row. In a @code{MyISAM} table the
above holds only if the columns are part of the same index.
@item
The @code{PRIMARY KEY} will be faster than any other key, as the
@code{PRIMARY KEY} is stored together with the row data. As the other keys are
stored as the key data + the @code{PRIMARY KEY}, it's important to keep the
@code{PRIMARY KEY} as short as possible to save disk and get better speed.
@item
@code{LOCK TABLES} works on @code{BDB} tables as with other tables. If
you don't use @code{LOCK TABLE}, MYSQL will issue an internal
multiple-write lock on the table to ensure that the table will be
properly locked if another thread issues a table lock.
@item
Internal locking in @code{BDB} tables is done on page level.
@item
@code{SELECT COUNT(*) FROM table_name} is slow as @code{BDB} tables doesn't
maintain a count of the number of rows in the table.
@item
Scanning is slower than with @code{MyISAM} tables as one has data in BDB
tables stored in B-trees and not in a separate data file.
@item
The application must always be prepared to handle cases where
any change of a @code{BDB} table may make an automatic rollback and any
read may fail with a deadlock error.
@item
Keys are not compressed to previous keys as with ISAM or MyISAM
tables. In other words, the key information will take a little more
space in @code{BDB} tables compared to MyISAM tables which don't use
@code{PACK_KEYS=0}.
@item
There is often holes in the BDB table to allow you to insert new rows in
the middle of the key tree. This makes BDB tables somewhat larger than
MyISAM tables.
@item
The optimizer needs to know an approximation of the number of rows in
the table. MySQL solves this by counting inserts and
maintaining this in a separate segment in each BDB table. If you don't
do a lot of @code{DELETE} or @code{ROLLBACK}:s this number should be
accurate enough for the MySQL optimizer, but as MySQL
only store the number on close, it may be wrong if MySQL dies
unexpectedly. It should not be fatal even if this number is not 100 %
correct. One can update the number of rows by executing @code{ANALYZE
TABLE} or @code{OPTIMIZE TABLE}. @xref{ANALYZE TABLE} . @xref{OPTIMIZE
TABLE}.
@item
If you get full disk with a @code{BDB} table, you will get an error
(probably error 28) and the transaction should roll back. This is in
contrast with @code{MyISAM} and @code{ISAM} tables where @code{mysqld} will
wait for enough free disk before continuing.
@end itemize
@node BDB TODO, BDB portability, BDB characteristic, BDB
@subsection Some things we need to fix for BDB in the near future:
@itemize @bullet
@item
It's very slow to open many BDB tables at the same time. If you are
going to use BDB tables, you should not have a very big table cache (>
256 ?) and you should use @code{--no-auto-rehash} with the @code{mysql}
client. We plan to partly fix this in 4.0.
@item
@code{SHOW TABLE STATUS} doesn't yet provide that much information for BDB
tables.
@item
Optimize performance.
@item
Change to not use page locks at all when we are scanning tables.
@end itemize
@node BDB portability, BDB errors, BDB TODO, BDB
@subsection Operating systems supported by @strong{BDB}
If you after having built MySQL with support for BDB tables get
the following error in the log file when you start @code{mysqld}:
@example
bdb: architecture lacks fast mutexes: applications cannot be threaded
Can't init dtabases
@end example
This means that @code{BDB} tables are not supported for your architecture.
In this case you have to rebuild MySQL without BDB table support.
NOTE: The following list is not complete; We will update this as we get
more information about this.
Currently we know that BDB tables works with the following operating
system.
@itemize @bullet
@item
Linux 2.x intel
@item
Solaris sparc
@item
SCO OpenServer
@item
SCO UnixWare 7.0.1
@end itemize
It doesn't work with the following operating systems:
@itemize @bullet
@item
Linux 2.x Alpha
@item
Max OS X
@end itemize
@node BDB errors, , BDB portability, BDB
@subsection Errors You May Get When Using BDB Tables
@itemize @bullet
@item
If you get the following error in the @code{hostname.err log} when
starting @code{mysqld}:
@example
bdb: Ignoring log file: .../log.XXXXXXXXXX: unsupported log version #
@end example
it means that the new @code{BDB} version doesn't support the old log
file format. In this case you have to delete all @code{BDB} log BDB
from your database directory (the files that has the format
@code{log.XXXXXXXXXX} ) and restart @code{mysqld}. We would also
recommend you to do a @code{mysqldump --opt} of your old @code{BDB}
tables, delete the old table and restore the dump.
@item
If you are running in not @code{auto_commit} mode and delete a table you
are using by another thread you may get the following error messages in
the MySQL error file:
@example
001119 23:43:56 bdb: Missing log fileid entry
001119 23:43:56 bdb: txn_abort: Log undo failed for LSN: 1 3644744: Invalid
@end example
This is not fatal but we don't recommend that you delete tables if you are
not in @code{auto_commit} mode, until this problem is fixed (the fix is
not trivial).
@end itemize
@node Clients, Extending MySQL, Table types, Top
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