The Merge Storage Engine - Oracle 5.0 Reference Manual

• Currently, cascaded foreign key actions do not activate triggers.
• You cannot create a table with a column name that matches the name of an internal InnoDB column
(including DB_ROW_ID, DB_TRX_ID, DB_ROLL_PTR, and DB_MIX_ID). In versions of MySQL before
5.0.21 this would cause a crash, since 5.0.21 the server will report error 1005 and refers to error –1
in the error message. This restriction applies only to use of the names in uppercase.
• As of MySQL 5.0.19,
VARBINARY
Locking and Transactions
•
LOCK TABLES
addition to a table lock on the MySQL layer, it also acquires an
MySQL before 4.1.2 did not acquire
innodb_table_locks=0. If no
some records of the tables are being locked by other transactions.
• All
InnoDB
aborted. Thus, it does not make much sense to invoke
autocommit=1
immediately.
• You cannot lock additional tables in the middle of a transaction because
implicit
COMMIT
• has a limit of 1023 concurrent transactions that have created undo records by modifying
InnoDB
data. Workarounds include keeping transactions as small and fast as possible, delaying changes
until near the end of the transaction, and using stored routines to reduce client/server latency delays.
Applications should commit transactions before doing time-consuming client-side operations.
14.3. The
MERGE
The
MERGE
tables that can be used as one. "Identical" means that all tables have identical column and index
information. You cannot merge
not have exactly the same columns, or have the indexes in different order. However, any or all of the
tables can be compressed with myisampack. See
MyISAM
Compressed, Read-Only MyISAM
MAX_ROWS, or
When you create a
the table name and have an extension to indicate the file type. An
and an
.MRG
tables do not have to be in the same database as the
You can use SELECT, DELETE, UPDATE, and
[577], and
DELETE
Use of
DROP TABLE
not affected.
The
does not ignore trailing spaces when comparing
InnoDB
column values. See
acquires two locks on each table if
locks held by a transaction are released when the transaction is committed or
[436] mode because the acquired
and
UNLOCK TABLES.
Storage Engine
storage engine, also known as the
MyISAM
do not matter.
PACK_KEYS
table, MySQL creates two files on disk. The files have names that begin with
MERGE
file contains the names of the underlying
[578] privileges on the
UPDATE
Note
The use of
MERGE
access to
MyISAM
t. However, if the user's privileges on
continue to access
can start the server with the new
storage engine. This option is available as of MySQL 5.0.24.
MERGE
with a
MERGE
Storage Engine
MERGE
Section 11.1.6.2, "The
innodb_table_locks=1
table locks; the old behavior can be selected by setting
InnoDB
table lock is acquired,
InnoDB
InnoDB
MRG_MyISAM
tables in which the columns are listed in a different order, do
Tables". Differences in table options such as AVG_ROW_LENGTH,
MyISAM
MERGE
on
INSERT
MyISAM
tables entails the following security issue: If a user has
table t, that user can create a
by doing so through m. If this behavior is undesirable, you
t
--skip-merge
table drops only the
MERGE
1300
and
BINARY VARBINARY
table lock. Versions of
InnoDB
LOCK TABLES
on
LOCK TABLES InnoDB
table locks would be released
LOCK TABLES
engine, is a collection of identical
Section 4.6.5, "myisampack
file stores the table format,
.frm
tables that should be used as one. The
table.
tables. You must have
MERGE
tables that you map to a
table
MERGE
are subsequently revoked, the user can
t
[420] option to disable the
specification. The underlying tables are
or
BINARY
Types".
(the default). In
completes even if
tables in
performs an
MyISAM
— Generate
[578],
SELECT
table.
MERGE
that accesses
m