When using multiples instances of MySQL on a single i5 host
you should be aware that the two independent instances will
access the same database within the DB2 environment. This can
lead to namespace collisions and issues. To get round this
limitation, you should configure different IBM i independent
auxilliary storage pools (ISAPs) for each MySQL server, and
then use the ibmdb2i_rdb_name
option to
MySQL to configure which IASP should be used for each MySQL
instance.
Indexes over VARBINARY
columns may not
provide accurate estimates the optimizer. Queries over such
indexes may produce error 2027 in the error log but will
succeed. This affects only the performance of these queries,
not the correctness of the results.
Setting ibmdb2i_system_trace_level = 16
(STRTRC)
may cause unpredictable failures including
error 2088 on some operations. This is unlikely to affect any
users, as this value is recommended only for serviceability
purposes.
IBMDB2I
honors the
CASCADE
/RESTRICT
option
on the DROP TABLE
command.
The use of FLUSH TABLES WITH READ LOCK
is
discouraged when using IBMDB2I
tables. Due
to differences in internal locking implementations,
FLUSH TABLES WITH READ LOCK
may produce
deadlocks on IBMDB2I
tables.
Row-based replication is supported by
IBMDB2I
. Statement-based replication is not
supported.
Schema name lengths are limited to 10 characters in IBM i 5.4 and 30 characters in IBM i 6.1. If the schema name is mixed- or lower-case, two characters must be subtracted from the limit to account for surrounding quotes.
The RENAME TABLE command cannot be used to move
IBMDB2I
tables from one database to
another.
The maximum length of the internal row format for
IBMDB2I
is 32767 bytes. Because the
internal row format may differ from the MySQL row format due
to data mapping differences (see Creating schemas and tables
section), anticipating this limit may be difficult.
The combined length of the index and table names must be less than or equal to 121 characters.
Indexes over TEXT or BLOB columns with a maximum length greater than 255 characters are not supported. The ibmdb2i_map_blob_to_varchar option can be used to work around this limitation for TEXT fields up to 64K characters.
Specific restrictions apply to certain data types as described in the following chart:
Table 13.8. Data Type Restrictions in IBMDB2I
MySQL data type | Restriction |
---|---|
LONGBLOB or LONGTEXT
|
The maximum length of a DB2 BLOB data type is 2GB. |
DATE |
IBMDB2I does not support the special date value of
'0000-00-00'. The restrictions on
DATE and
DATETIME columns can be removed by
setting the value of
ibmdb2i_compat_opt_allow_zero_date_vals
to 1. |
DATETIME |
IBMDB2I does not support the special datetime value
of '0000-00-00 00:00:00'. The restrictions on
DATE and
DATETIME columns can be removed by
setting the value of
ibmdb2i_compat_opt_allow_zero_date_vals
to 1. |
DECIMAL(p, s) or NUMERIC(p, s)
|
If p is greater than 63 and s is greater than (p-63), the field
definition is truncated to DECIMAL(63,
s-(p-63)) . If p is greater than 63 and s is
less than or equal to (p-63), the definition is not
supported. |
TIME |
By default, IBMDB2I only supports times in the range
'00:00:00' to '23:59:59.' See the
ibmdb2i_create_time_columns_as_tod option for more
information. |
These MySQL statements are not supported by the
IBMDB2I
Engine:
CACHE INDEX
and LOAD INDEX
INTO CACHE
HANDLER
CHECK TABLE
REPAIR TABLE
The ucs2_spanish2_ci
and
utf8_spanish2_ci
collations are not
supported by IBMDB2I
. There are no plans to
support these collations.
The ucs2_swedish_ci
and
utf8_swedish_ci
collations are not
supported by IBMDB2I
. This will be fixed in
a subsequent release of the storage engine; as with other
language-specific unicode collations, the support will be only
be available on IBM i 6.1 and later releases.
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