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
auxiliary 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
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.
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
IBMDB2I honors the
DROP TABLE statement.
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
Row-based replication is supported by
IBMDB2I. Statement-based replication is not
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 quotation marks.
The RENAME TABLE command cannot be used to move
IBMDB2I tables from one database to
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 14.9 Data Type Restrictions in IBMDB2I
|MySQL data type||Restriction|
|The maximum length of a DB2 BLOB data type is 2GB.|
|If p is greater than 63 and s is greater than (p-63), the field
definition is truncated to |
|By default, |
These MySQL statements are not supported by the
CACHE INDEX and
utf8_spanish2_ci collations are not
IBMDB2I. There are no plans to
support these collations.
utf8_swedish_ci collations were added in
MySQL 5.1.35. supported by
IBMDB2I. As with
other language-specific unicode collations, the support will
be only be available on IBM i 6.1 and later releases.