The problem is that since MyISAM's concurrent_insert is on by
default some concurrent SELECT statements might not see changes
made by INSERT statements in other connections, even if the
INSERT statement has returned.
The solution is to disable concurrent_insert so that INSERT
statements returns after the data is actually visible to other
statements.
correctly - crashes server !
Creating federated table with connect string containing empty
(zero-length) host name and port is evaluated as 0 (port is
incorrect, omitted or 0) crashes server.
This happens because federated calls strcmp() with NULL pointer.
Fixed by avoiding strcmp() call if hostname is set to NULL.
from storage engine
Federated may crash a server, return wrong result set, return
"ERROR 1030 (HY000): Got error 1430 from storage engine" message
when local (engine=federated) table has a key against nullable
column.
The problem was wrong implementation of function that creates
WHERE clause for remote query from key.
filesort() uses file->estimate_rows_upper_bound() call to allocate
internal buffers. If this function returns a value smaller than
a number of row that will be returned later in find_all_keys(),
that can cause server crash.
Fixed by implementing ha_federated::estimate_rows_upper_bound() to
return maximum possible number of rows.
Present estimation for FEDERATED always returns 0 if the linked to the VIEW.
"Federated Denial of Service"
Federated storage engine used to attempt to open connections within
the ::create() and ::open() methods which are invoked while LOCK_open
mutex is being held by mysqld. As a result, no other client sessions
can open tables while Federated is attempting to open a connection.
Long DNS lookup times would stall mysqld's operation and a rogue
connection string which connects to a remote server which simply
stalls during handshake can stall mysqld for a much longer period of
time.
This patch moves the opening of the connection much later, when the
federated actually issues queries, by which time the LOCK_open mutex is
no longer being held.
when creating table
Federated tables had an artificially low maximum of key length,
because the handler failed to implement a method to return it and
the default value is taked from the prototype handler.
Now, implement that method and return the maximum possible key
length, which is that of InnoDB.
"Federated INSERT failures"
Federated does not correctly handle "INSERT...ON DUPLICATE KEY UPDATE"
However, implementing such support is not reasonably possible without
increasing complexity of the storage engine: checking that constraints
on remote server match local server and parsing error messages.
This patch causes 'ON DUPLICATE KEY' to fail with ER_DUP_KEY message
if a conflict occurs and not to fail silently.
"REPLACE/INSERT IGNORE/UPDATE IGNORE doesn't work"
Federated does not record neccessary HA_EXTRA flags in order to
support REPLACE/INSERT IGNORE/UPDATE IGNORE.
Implement ::extra() to capture flags neccessary for functionality.
New function append_ident() to better escape identifiers consistantly.
- Added 'SET NAMES <charset>" upon ::open
- Added test and results for simple UTF test
federated.test:
BUG #17044 Federated Storage Engine not UTF8 clean
New test. Using hex - pasting various charsets in the terminal doesn't work.
federated.result:
BUG# 17044 Federated Storage Engine not UTF8 clean
New test results
ha_federated.cc:
BUG# 17044 Federated Storage Engine not UTF8 clean
Upon ::open, set names to table's charset
into govinda.patg.net:/home/patg/mysql-build/mysql-5.1-5.0-merge2
Push by holyfoot@production.mysql.com on Tue Jul 25 13:41:40 2006:
bk clone -l -r'holyfoot/hf@mysql.com/deer.(none)|ChangeSet|20060725085017|41021' mysql-5.0 tmp_merge
Added HA_NULL_IN_KEY to table flags to allow for nullable unique indexes
and added test to verify
ha_federated.h:
BUG #15133 "unique index with nullable value not accepted in federated table"
added HA_NULL_IN_KEY to table flags to allow for nullable unique indexes
federated.test:
BUG #15133 "unique index with nullable value not accepted in federated table"
New test to show that nullable unique indexes work
federated.result:
BUG #15133 "unique index with nullable value not accepted in federated table"
New results for new test
When a default of '' was specified for TEXT/BLOB columns, the specification
was silently ignored. This is presumably to be nice to applications (or
people) who generate their column definitions in a not-very-clever fashion.
For clarity, doing this now results in a warning, or an error in strict
mode.
The Federated storage engine used Field methods that had arbitrary limits on
the amount of data they could process, which caused problems with data
over that limit (4K). By removing those Field methods and just using
features of the String class, we can avoid this problem.
