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MXS-2785: Update binlogfilter documentation

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Updated the documentation with the regex changes and listed some of the
caveats of rewriting SQL with regular expressions.
This commit is contained in:
Markus Mäkelä
2019-12-09 11:22:03 +02:00
parent 689a284892
commit 1ef130a870
1 changed files with 16 additions and 21 deletions
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37
Documentation/Filters/BinlogFilter.md
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@ -37,32 +37,27 @@ in the statements. If any of the tables matches the *match* pattern, the event
is replicated. If any of the tables matches the *exclude* pattern, the event is is replicated. If any of the tables matches the *exclude* pattern, the event is
not replicated. not replicated.
### `rewrite_src` ### `rewrite_src` and `rewrite_dest`
The old database name to a rewritten statement. When database name rewriting is These two parameters control the statement rewriting of the binlogfilter. The
enabled, all occurrences of the old database name (`rewrite_src`) are replaced `rewrite_src` parameter is a PCRE2 regular expression that is matched against
with the new replacement database name (`rewrite_dest`). Both `rewrite_src` and the default database and the SQL of statement based replication events (query
`rewrite_dest` must be defined if database rewriting is to be enabled. events). `rewrite_dest` is the replacement string which supports the normal
PCRE2 backreferences (e.g the first capture group is `$1`, the second is `$2`,
etc.).
The name replacement is done with simple string replacement. This means that the Both `rewrite_src` and `rewrite_dest` must be defined to enable statement rewriting.
database name (`rewrite_src`) **must not** appear as a table name, a field name
or any other identifier, as a part of a constant value and must not conflict
with SQL keywords. If the name does appear as a non-database identifier,
replication will either break or behave in an undefined manner.
We highly recommend using When statement rewriting is enabled
[GTID-based replication](https://mariadb.com/kb/en/library/gtid/#setting-up-a-new-slave-server-with-global-transaction-id) [GTID-based replication](https://mariadb.com/kb/en/library/gtid/#setting-up-a-new-slave-server-with-global-transaction-id)
when using statement rewriting. If `rewrite_dest` is longer than `rewrite_src`, must be used. The filter will disallow replication for all slaves that attempt
the replication must use GTID coordinates. Otherwise, the replication can break to replicate with traditional file-and-position based replication.
down when a slave server is disconnected. The filter will disallow replication
for all slaves that attempt to replicate with traditional file-and-position
based replication when the new database name is longer than the old name.
### `rewrite_dest` The replacement is done both on the default database as well as the SQL
statement in the query event. This means that great care must be taken when
The new database name of a rewritten statement. Both `rewrite_src` and defining the rewriting rules. To prevent accidental modification of the SQL into
`rewrite_dest` must be defined if database rewriting is to be enabled. See a form that is no longer valid, use database and table names that never occur in
[`rewrite_src`](#rewrite_src) for details on how this feature works. the inserted data and is never used as a constant value.
## Example Configuration ## Example Configuration