comments)
Before this fix, the server would accept queries that contained comments,
even when the comments were not properly closed with a '*' '/' marker.
For example,
select 1 /* + 2 <EOF>
would be accepted as
select 1 /* + 2 */ <EOF>
and executed as
select 1
With this fix, the server now rejects queries with unclosed comments
as syntax errors.
Both regular comments ('/' '*') and special comments ('/' '*' '!') must be
closed with '*' '/' to be parsed correctly.
This is a performance bug, affecting in particular the bison generated code
for the parser.
Prior to this fix, the grammar used a long chain of reduces to parse an
expression, like:
bit_expr -> bit_term
bit_term -> bit_factor
bit_factor -> value_expr
value_expr -> term
term -> factor
etc
This chain of reduces cause the internal state automaton in the generated
parser to execute more state transitions and more reduces, so that the
generated MySQLParse() function would spend a lot of time looping to execute
all the grammar reductions.
With this patch, the grammar has been reorganized so that rules are more
"flat", limiting the depth of reduces needed to parse <expr>.
Tests have been written to enforce that relative priorities and properties
of operators have not changed while changing the grammar.
See the bug report for performance data.
If, after the tables are locked, one of the conditions to read from a
HANDLER table is not met, the handler code wrongly jumps to a error path
that won't unlock the tables.
The user-visible effect is that after a error in a handler read command,
all subsequent handler operations on the same table will hang.
The fix is simply to correct the code to jump to the (same) error path that
unlocks the tables.
The problem from a user's perspective: user creates table A, and then tries
to CREATE TABLE a SELECT from A - and this causes a deadlock error, a hang,
or fails with a debug assert, but only if the storage engine is InnoDB.
The origin of the problem: InnoDB uses case-insensitive collation
(system_charset_info) when looking up the internal table share, thus returning
the same share for 'a' and 'A'.
Cause of the user-visible behavior: since the same share is returned to SQL
locking subsystem, it assumes that the same table is first locked (within the
same session) for WRITE, and then for READ, and returns a deadlock error.
However, the code is wrong in not properly cleaning up upon an error, leaving
external locks in place, which leads to assertion failures and hangs.
Fix that has been implemented: the SQL layer should properly propagate the
deadlock error, cleaning up and freeing all resources.
Further work towards a more complete solution: InnoDB should not use case
insensitive collation for table share hash if table names on disk honor the case.
since this flag was explicitly removed in pushbuild for GCOV builds.
BUILD_CMD => ['sh', '-c', 'perl -i.bak -pe "s/ \\\\\$static_link//" ' .
'BUILD/compile-pentium-gcov; BUILD/compile-pentium-gcov'],
Moving $static_link to SETUP.sh broke this, and is now fixed.
Should this flag be needed on some platforms,
the proper location is compile-<platform>-gcov
Tested the amd64 and pentium64 build fine without it, and can run NDB tests.
This is a performance bug, related to the parsing or 'OR' and 'AND' boolean
expressions.
Let N be the number of expressions involved in a OR (respectively AND).
When N=1
For example, "select 1" involve only 1 term: there is no OR operator.
In 4.0 and 4.1, parsing expressions not involving OR had no overhead.
In 5.0, parsing adds some overhead, with Select->expr_list.
With this patch, the overhead introduced in 5.0 has been removed,
so that performances for N=1 should be identical to the 4.0 performances,
which are optimal (there is no code executed at all)
The overhead in 5.0 was in fact affecting significantly some operations.
For example, loading 1 Million rows into a table with INSERTs,
for a table that has 100 columns, leads to parsing 100 Millions of
expressions, which means that the overhead related to Select->expr_list
is executed 100 Million times ...
Considering that N=1 is by far the most probable expression,
this case should be optimal.
When N=2
For example, "select a OR b" involves 2 terms in the OR operator.
In 4.0 and 4.1, parsing expressions involving 2 terms created 1 Item_cond_or
node, which is the expected result.
In 5.0, parsing these expression also produced 1 node, but with some extra
overhead related to Select->expr_list : creating 1 list in Select->expr_list
and another in Item_cond::list is inefficient.
With this patch, the overhead introduced in 5.0 has been removed
so that performances for N=2 should be identical to the 4.0 performances.
Note that the memory allocation uses the new (thd->mem_root) syntax
directly.
The cost of "is_cond_or" is estimated to be neglectable: the real problem
of the performance degradation comes from unneeded memory allocations.
When N>=3
For example, "select a OR b OR c ...", which involves 3 or more terms.
In 4.0 and 4.1, the parser had no significant cost overhead, but produced
an Item tree which is difficult to evaluate / optimize during runtime.
In 5.0, the parser produces a better Item tree, using the Item_cond
constructor that accepts a list of children directly, but at an extra cost
related to Select->expr_list.
With this patch, the code is implemented to take the best of the two
implementations:
- there is no overhead with Select->expr_list
- the Item tree generated is optimized and flattened.
This is achieved by adding children nodes into the Item tree directly,
with Item_cond::add(), which avoids the need for temporary lists and memory
allocation
Note that this patch also provide an extra optimization, that the previous
code in 5.0 did not provide: expressions are flattened in the Item tree,
based on what the expression already parsed is, and not based on the order
in which rules are reduced.
For example : "(a OR b) OR c", "a OR (b OR c)" would both be represented
with 2 Item_cond_or nodes before this patch, and with 1 node only with this
patch. The logic used is based on the mathematical properties of the OR
operator (it's associative), and produces a simpler tree.
Although the query cache doesn't support retrieval of statements containing
column level access control, it was still possible to cache such statements
thus wasting memory.
This patch extends the access control check on the target tables to avoid
caching a statement with column level restrictions.
Views are excepted and can be cached but only retrieved by super user account.
Although the query cache doesn't support retrieval of statements containing
column level access control, it was still possible to cache such statements
thus wasting memory.
This patch extends the access control check on the target tables to avoid
caching a statement with column level restrictions.
This is a follow up for the patch for Bug#26162 "Trigger DML ignores low_priority_updates setting", where the stored procedure ignores the session setting of low_priority_updates.
For every table open operation with default write (TL_WRITE_DEFAULT) lock_type, downgrade the lock type to the session setting of low_priority_updates.
This patch provides compile helper scripts only,
no server logic is affected.
Before this patch, GCOV and GPROF build scripts were only provided for
pentium platforms.
With this patch, pentium, pentium64 and amd64 platforms have associated
helper build scripts.
The GCOV and GPROF specific compilation flags are set once in SETUP.sh,
to avoid code duplication.
Apply innodb-5.0-ss1696 snapshot
Fixes:
- Bug#20090: InnoDB: Error: trying to declare trx to enter InnoDB
- Bug#23710: crash_commit_before fails if innodb_file_per_table=1
At InnoDB startup consider the case where log scan went beyond
checkpoint_lsn as a crash and initiate crash recovery code path.
- Bug#28781: InnoDB increments auto-increment value incorrectly with ON DUPLICATE KEY UPDATE
We need to do some special AUTOINC handling for the following case:
INSERT INTO t (c1,c2) VALUES(x,y) ON DUPLICATE KEY UPDATE ...
We need to use the AUTOINC counter that was actually used by
MySQL in the UPDATE statement, which can be different from the
value used in the INSERT statement.
- Bug#29097: fsp_get_available_space_in_free_extents() is capped at 4TB
Fix by typecasting the variables before multiplying them, so that the
result of the multiplication is of type "unsigned long long".
- Bug#29155: Innodb "Parallel recovery" is not prevented
Fix by enabling file locking on FreeBSD. It has been disabled because
InnoDB has refused to start on FreeBSD & LinuxThreads, but now it
starts just fine.
mysql_ha_open calls mysql_ha_close on the error path (unsupported) to close the (opened) table before inserting it into the tables hash list handler_tables_hash) but mysql_ha_close only closes tables which are on the hash list, causing the table to be left open and locked.
This change moves the table close logic into a separate function that is always called on the error path of mysql_ha_open or on a normal handler close (mysql_ha_close).
under terms of bug#28875 for better performance.
The change appeared to require more changes in item_cmpfunc.cc,
which is dangerous in 5.0.
Conversion between a latin1 column and an ascii string constant
stopped to work.
Two character mappings were way off (backtick and tilde were "E"
and "Y"!), and three others were slightly rotated. The first
would cause collisions, and the latter was probably benign.
Now, assign the character mappings exactly to their normal values.
MySQL replicates the time zone only when operations that involve
it are performed. This is controlled by a flag. But this flag
is set only on successful operation.
The flag must be set also when there is an error that involves
a timezone (so the master would replicate the error to the slaves).
Fixed by moving the setting of the flag before the operation
(so it apples to errors as well).
VIEW".
mysql_list_fields() C API function would incorrectly set MYSQL_FIELD::decimals
member for some view columns.
The problem was in an incomplete implementation of
Item_ident_for_show::make_field(), which is responsible for view
columns metadata.
This bug manifested itself for queries with grouping by columns of
the BIT type. It led to wrong comparisons of bit-field values and
wrong result sets.
Bit-field values never cannot be compared as binary values. Yet
the class Field_bit had an implementation of the cmp method that
compared bit-fields values as binary values.
Also the get_image and set_image methods of the base class Field
cannot be used for objects of the Field_bit class.
Now these methods are declared as virtual and specific implementations
of the methods are provided for the class Field_bit.
