When compressed myisam files are opened, they are always memory mapped
sometimes causing memory swapping problems.
When we mmap the myisam compressed tables of size greater than the memory
available, the kswapd0 process utilization is very high consuming 30-40% of
the cpu. This happens only with linux kernels older than 2.6.9
With newer linux kernels, we don't have this problem of high cpu consumption
and this option may not be required.
The option 'myisam_mmap_size' is added to limit the amount of memory used for
memory mapping of myisam files. This option is not dynamic.
The default value on 32 bit system is 4294967295 bytes and on 64 bit system it
is 18446744073709547520 bytes.
Note: Testcase only tests the option variable. The actual bug has be to
tested manually.
returns incorrect results with where
An outer join of a const table (outer) and a normal table
(inner) with GROUP BY on a field from the outer table would
optimize away GROUP BY, and thus trigger the optimization to
do away with a temporary table if grouping was performed on
columns from the const table, hence executing the query with
filesort without temporary table. But this should not be
done if there is a non-indexed access to the inner table,
since filesort does not handle joins. It expects either ref
access, range ditto or table scan. The join condition will
thus not be applied.
Fixed by always forcing execution with temporary table in
the case of ROLLUP with a query involving an outer join. This
is a slightly broader class of queries than need fixing, but
it is hard to ascertain the position of a ROLLUP field wrt
outer join with current query representation.
Problem: inserting a record we don't set unused null bits in the
record buffer if no default field values used.
That may lead to wrong live checksum calculation.
Fix: set unused null bits in the record buffer in such cases.
int join_read_key(JOIN_TAB*)
The eq_ref access method TABLE_REF (accessed through
JOIN_TAB) to save state and to track if this is the
first row it finds or not.
This state was not reset on subquery re-execution
causing an assert.
Fixed by resetting the state before the subquery
re-execution.
NULLable BIGINT and INT columns in comparison
Problem: a consequence of the fix for 43668.
Some Arg_comparator inner initialization missed,
that may lead to unpredictable (wrong) comparison
results.
Fix: always properly initialize Arg_comparator
before its usage.
int join_read_key(JOIN_TAB*)
The eq_ref access method TABLE_REF (accessed through
JOIN_TAB) to save state and to track if this is the
first row it finds or not.
This state was not reset on subquery re-execution
causing an assert.
Fixed by resetting the state before the subquery
re-execution.
check_key_in_view() had one code branch which returned with "return TRUE"
rather than "DBUG_RETURN(TRUE)". Only affected debug builds.
No test case added.
Problem is that purge_logs implementation in ndb (ndbcluster_binlog_index_purge_file)
calls mysql_parse (with (thd->options & OPTION_BIN_LOG) === 0))
but MYSQL_BIN_LOG first takes LOCK_log and then checks thd->options
Solution in this patch, changes so that rotate_and_purge does not hold
LOCK_log when calling purge_logs_before_date. I think this is safe
as other "purge"-function(s) is called wo/ holding LOCK_log, e.g purge_master_logs
'LOAD DATA CONCURRENT [LOCAL] INFILE ...' statment only is binlogged as
'LOAD DATA [LOCAL] INFILE ...' in SBR and MBR. As a result, if replication is on,
queries on slaves will be blocked by the replication SQL thread.
This patch write code to write 'CONCURRENT' into the log event if 'CONCURRENT' option
is in the original statement in SBR and MBR.
5.0 buffer overflow for ER_UPDATE_INFO, or truncated info message in 5.1
5.0.86 has a buffer overflow/crash, and 5.1.40 has a truncated message.
errmsg.txt contains this:
ER_UPDATE_INFO
rum "Linii identificate (matched): %ld Schimbate: %ld Atentionari
(warnings): %ld"
When that is sprintf'd into a buffer of STRING_BUFFER_USUAL_SIZE size,
a buffer overflow can happen.
The solution to this is to use MYSQL_ERRMSG_SIZE for the buffer size,
instead of STRING_BUFFER_USUAL_SIZE. This will allow longer strings.
To avoid potential crashes, we will also use my_snprintf instead of
sprintf.
timestamp primary key
Since TIMESTAMP values are adjusted by the current time zone
settings in both numeric and string contexts, using any
expressions involving TIMESTAMP values as a
(sub)partitioning function leads to undeterministic behavior of
partitioned tables. The effect may vary depending on a storage
engine, it can be either incorrect data being retrieved or
stored, or an assertion failure. The root cause of this is the
fact that the calculated partition ID may differ from a
previously calculated ID for the same data due to timezone
adjustments of the partitioning expression value.
Fixed by disabling any expressions involving TIMESTAMP values
to be used in partitioning functions with the follwing two
exceptions:
1. Creating or altering into a partitioned table that violates
the above rule is not allowed, but opening existing such tables
results in a warning rather than an error so that such tables
could be fixed.
2. UNIX_TIMESTAMP() is the only way to get a
timezone-independent value from a TIMESTAMP column, because it
returns the internal representation (a time_t value) of a
TIMESTAMP argument verbatim. So UNIX_TIMESTAMP(timestamp_column)
is allowed and should be used to fix existing tables if one
wants to use TIMESTAMP columns with partitioning.
