Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
for InnoDB
The class Field_bit_as_char stores the metadata for the
field incorrecly because bytes_in_rec and bit_len are set
to (field_length + 7 ) / 8 and 0 respectively, while
Field_bit has the correct values field_length / 8 and
field_length % 8.
Solved the problem by re-computing the values for the
metadata based on the field_length instead of using the
bytes_in_rec and bit_len variables.
To handle compatibility with old server, a table map
flag was added to indicate that the bit computation is
exact. If the flag is clear, the slave computes the
number of bytes required to store the bit field and
compares that instead, effectively allowing replication
*without conversion* from any field length that require
the same number of bytes to store.
In BUG#51787 we were using the wrong charset to print out the
data. We were using the field charset for the string that would
hold the information. This caused the assertion, because the
string length was not aligned with UTF32 bytes requirements for
storage.
We fix this by using &my_charset_latin1 in the string object
instead of the field->charset(). As a side-effect, we needed to
extend the show_sql_type interface so that it took the field
charset is now passed as a parameter, so that one is able to
calculate the correct field size.
In BUG#51716 we had issues with Field_string::pack and
Field_string::unpack. When packing, the length was incorrectly
calculated. When unpacking, the padding the string would be
padded with the wrong bytes (a few bytes less than it should).
We fix this by resorting to charset abstractions (functions) that
calculate the correct length when packing and pad correctly the
string when unpacking.
replicating
Replace c_ptr() calls with c_ptr_safe() calls to
avoid valgrind warnings.
Adding code to to handle the case that no metadata
was present in the table map for the column.
Allow first parameter to unpack_row() to be NULL,
in which case no source tables is used and hence
no checks nor conversions are done.
Clarifying some comments and fixing documentation
for unpack_row().
WL#5151 was pushed.
Problem 1: Some old binlog events do not contain metadata. This
makes checking whether the field can be converted or not rather
impossible because one cannot compare, for instance, field sizes
from original table and target table.
Solution 1: When an event does not contain metadata, we will just
check if field types are equal and assume that original field
definition matched with the one in the target table.
Problem 2: There is a second fix, which involves lack of
information regarding maybe_null. This was causing a conditional
jump warning when creating a conversion table.
Solution 2: We will just assume that all fields that need to be
in the conversion table may be null.
Metadata for geometric fields was not being properly stored by
the slave in its the table definition. This happened because
MYSQL_TYPE_GEOMETRY was not included in the 'switch... case' that
handles field metadata according to the field type. Therefore, it
would default to 0, leading to always have a mismatch between
master's field and slave fields'.
We fix this by deploying the missing 'case MYSQL_TYPE_GEOMETRY:'.
This patch fixes these warnings and some compile time warnings.
On top of that, it also fixes rpl_err_ignoredtable test failure.
This test was failing because the warning suppression text was not
matching the latest text. We fix this by making them match.
for InnoDB
The class Field_bit_as_char stores the metadata for the
field incorrecly because bytes_in_rec and bit_len are set
to (field_length + 7 ) / 8 and 0 respectively, while
Field_bit has the correct values field_length / 8 and
field_length % 8.
Solved the problem by re-computing the values for the
metadata based on the field_length instead of using the
bytes_in_rec and bit_len variables.
To handle compatibility with old server, a table map
flag was added to indicate that the bit computation is
exact. If the flag is clear, the slave computes the
number of bytes required to store the bit field and
compares that instead, effectively allowing replication
*without conversion* from any field length that require
the same number of bytes to store.
Row-based replication requires the types of columns on the
master and slave to be approximately the same (some safe
conversions between strings are allowed), but does not
allow safe conversions between fields of similar types such
as TINYINT and INT.
This patch implement type conversions between similar fields
on the master and slave.
The conversions are controlled using a new variable
SLAVE_TYPE_CONVERSIONS of type SET('ALL_LOSSY','ALL_NON_LOSSY').
Non-lossy conversions are any conversions that do not run the
risk of losing any information, while lossy conversions can
potentially truncate the value. The column definitions are
checked to decide if the conversion is acceptable.
If neither conversion is enabled, it is required that the
definitions of the columns are identical on master and slave.
Conversion is done by creating an internal conversion table,
unpacking the master data into it, and then copy the data to
the real table on the slave.
In order to handle CHAR() fields, 8 bits were reserved for
the size of the CHAR field. However, instead of denoting the
number of characters in the field, field_length was used which
denotes the number of bytes in the field.
Since UTF-8 fields can have three bytes per character (and
has been extended to have four bytes per character in 6.0),
an extra two bits have been encoded in the field metadata
work for fields of type Field_string (i.e., CHAR fields).
Since the metadata word is filled, the extra bits have been
encoded in the upper 4 bits of the real type (the most
significant byte of the metadata word) by computing the
bitwise xor of the extra two bits. Since the upper 4 bits
of the real type always is 1111 for Field_string, this
means that for fields of length <256, the encoding is
identical to the encoding used in pre-5.1.26 servers, but
for lengths of 256 or more, an unrecognized type is formed,
causing an old slave (that does not handle lengths of 256
or more) to stop.
This patch clarifies some of the coding choices with documentationa and
removes a limitation in the code for future expansion of the CHAR and
BINARY fields to length > 255.
using TPC-B):
Problem: A RBR event can contain incomplete row data (only key value and
fields which have been changed). In that case, when the row is unpacked
into record and written to a table, the missing fields get incorrect NULL
values leading to master-slave inconsistency.
Solution: Use values found in slave's table for columns which are not given
in the rows event. The code for writing a single row uses the following
algorithm:
1. unpack row_data into table->record[0],
2. try to insert record,
3. if duplicate record found, fetch it into table->record[0],
4. unpack row_data into table->record[0],
5. write table->record[0] into the table.
Where row_data is the row as stored in the data area of a rows event.
Thus:
a) unpacking of row_data happens at the time when row is written into
a table,
b) when unpacking (in step 4), only columns present in row_data are
overwritten - all other columns remain as they were found in the table.
Since all data needed for the above algorithm is stored inside
Rows_log_event class, functions which locate and write rows are turned
into methods of that class.
replace_record() -> Rows_log_event::write_row()
find_and_fetch_row() -> Rows_log_event::find_row()
Both methods take row data from event's data buffer - the row being
processed is pointed by m_curr_row. They unpack the data as needed into
table's record buffers record[0] or record[1]. When row is unpacked,
m_curr_row_end is set to point at next row in the data buffer.
Other changes introduced in this changeset:
- Change signature of unpack_row(): don't report errors and don't
setup table's rw_set here. Errors can happen only when setting default
values in prepare_record() function and are detected there.
- In Rows_log_event and derived classes, don't pass arguments to
the execution primitives (do_...() member functions) but use class
members instead.
- Move old row handling code into log_event_old.cc to be used by
*_rows_log_event_old classes.
Also, a new test rpl_ndb_2other is added which tests basic replication
from master using ndb tables to slave storing the same tables using
(possibly) different engine (myisam,innodb).
Test is based on existing tests rpl_ndb_2myisam and rpl_ndb_2innodb.
However, these tests doesn't work for various reasons and currently are
disabled (see BUG#19227).
The new test differs from the ones it is based on as follows:
1. Single test tests replication with different storage engines on slave
(myisam, innodb, ndb).
2. Include file extra/rpl_tests/rpl_ndb_2multi_eng.test containing
original tests is replaced by extra/rpl_tests/rpl_ndb_2multi_basic.test
which doesn't contain tests using partitioned tables as these don't work
currently. Instead, it tests replication to a slave which has more or
less columns than master.
3. Include file include/rpl_multi_engine3.inc is replaced with
include/rpl_multi_engine2.inc. The later differs by performing slightly
different operations (updating more than one row in the table) and
clearing table with "TRUNCATE TABLE" statement instead of "DELETE FROM"
as replication of "DELETE" doesn't work well in this setting.
4. Slave must use option --log-slave-updates=0 as otherwise execution of
replication events generated by ndb fails if table uses a different
storage engine on slave (see BUG#29569).
This patch adds functionality to row-based replication to ensure the
slave's column sizes are >= to that of the master.
It also includes some refactoring for the code from WL#3228.
This patch corrects a problem found during testing on Solaris. The code
changes how length values are retrieved on big endian machines. The
patch allows the rpl_extraColmaster tests to run on these machines.
This patch adds the ability to store extra field metadata in the table
map event. This data can include pack_length() or field_lenght() for
fields such as CHAR or VARCHAR enabling developers to add code that
can check for compatibilty between master and slave columns. More
importantly, the extra field metadata can be used to store data from the
master correctly should a VARCHAR field on the master be <= 255 bytes
while the same field on the slave is > 255 bytes.
The patch also includes the needed changes to unpack to ensure that data
which is smaller on the master can be unpacked correctly on the slave.
WL#3915 : (NDB) master's cols > slave
Slave starts accepting and handling rows of master's tables which have more columns.
The most important part of implementation is how to caclulate the amount of bytes to
skip for unknown by slave column.
Adding new fields Last_{IO,SQL}_Errno and Last_{IO,SQL}_Error to output
of SHOW SLAVE STATUS to hold errors from I/O and SQL thread respectively.
Old fields Last_Error and Last_Errno are aliases for Last_SQL_Error and
Last_SQL_Errno respectively.
Fields are added last to output of SHOW SLAVE STATUS to allow old applications
to use the same positional arguments into the row, while allowing new
application to benefit from the added information.
In addition, some new error codes are added (especially for the I/O
thread) to be able to provide sensible error message.
The following type conversions was done:
- Changed byte to uchar
- Changed gptr to uchar*
- Change my_string to char *
- Change my_size_t to size_t
- Change size_s to size_t
Removed declaration of byte, gptr, my_string, my_size_t and size_s.
Following function parameter changes was done:
- All string functions in mysys/strings was changed to use size_t
instead of uint for string lengths.
- All read()/write() functions changed to use size_t (including vio).
- All protocoll functions changed to use size_t instead of uint
- Functions that used a pointer to a string length was changed to use size_t*
- Changed malloc(), free() and related functions from using gptr to use void *
as this requires fewer casts in the code and is more in line with how the
standard functions work.
- Added extra length argument to dirname_part() to return the length of the
created string.
- Changed (at least) following functions to take uchar* as argument:
- db_dump()
- my_net_write()
- net_write_command()
- net_store_data()
- DBUG_DUMP()
- decimal2bin() & bin2decimal()
- Changed my_compress() and my_uncompress() to use size_t. Changed one
argument to my_uncompress() from a pointer to a value as we only return
one value (makes function easier to use).
- Changed type of 'pack_data' argument to packfrm() to avoid casts.
- Changed in readfrm() and writefrom(), ha_discover and handler::discover()
the type for argument 'frmdata' to uchar** to avoid casts.
- Changed most Field functions to use uchar* instead of char* (reduced a lot of
casts).
- Changed field->val_xxx(xxx, new_ptr) to take const pointers.
Other changes:
- Removed a lot of not needed casts
- Added a few new cast required by other changes
- Added some cast to my_multi_malloc() arguments for safety (as string lengths
needs to be uint, not size_t).
- Fixed all calls to hash-get-key functions to use size_t*. (Needed to be done
explicitely as this conflict was often hided by casting the function to
hash_get_key).
- Changed some buffers to memory regions to uchar* to avoid casts.
- Changed some string lengths from uint to size_t.
- Changed field->ptr to be uchar* instead of char*. This allowed us to
get rid of a lot of casts.
- Some changes from true -> TRUE, false -> FALSE, unsigned char -> uchar
- Include zlib.h in some files as we needed declaration of crc32()
- Changed MY_FILE_ERROR to be (size_t) -1.
- Changed many variables to hold the result of my_read() / my_write() to be
size_t. This was needed to properly detect errors (which are
returned as (size_t) -1).
- Removed some very old VMS code
- Changed packfrm()/unpackfrm() to not be depending on uint size
(portability fix)
- Removed windows specific code to restore cursor position as this
causes slowdown on windows and we should not mix read() and pread()
calls anyway as this is not thread safe. Updated function comment to
reflect this. Changed function that depended on original behavior of
my_pwrite() to itself restore the cursor position (one such case).
- Added some missing checking of return value of malloc().
- Changed definition of MOD_PAD_CHAR_TO_FULL_LENGTH to avoid 'long' overflow.
- Changed type of table_def::m_size from my_size_t to ulong to reflect that
m_size is the number of elements in the array, not a string/memory
length.
- Moved THD::max_row_length() to table.cc (as it's not depending on THD).
Inlined max_row_length_blob() into this function.
- More function comments
- Fixed some compiler warnings when compiled without partitions.
- Removed setting of LEX_STRING() arguments in declaration (portability fix).
- Some trivial indentation/variable name changes.
- Some trivial code simplifications:
- Replaced some calls to alloc_root + memcpy to use
strmake_root()/strdup_root().
- Changed some calls from memdup() to strmake() (Safety fix)
- Simpler loops in client-simple.c
Second patch to fix skipping code. Moving relay and binary log
position changing code from do_apply_event [old exec_event()] into
do_update_pos() and doing other changes necessary to support that.
Fixing a bug that can cause deadlock if rotating binary log when committing
a changes to a transactional table that is not inside a transaction and
cause a rotate log.
