- Remove bothersome warning messages. This change focuses on the warnings
that are covered by the ignore file: support-files/compiler_warnings.supp.
- Strings are guaranteed to be max uint in length
The problem is that the query cache was storing partial results
if the statement failed when sending the results to the client.
This could cause clients to hang when trying to read the results
from the cache as they would, for example, wait indefinitely for
a eof packet that wasn't saved.
The solution is to always discard the caching of a query that
failed to send its results to the associated client.
The problem is that the query cache stores packets containing
the server status of the time when the cached statement was run.
This might lead to a wrong transaction status in the client side
if a statement is cached during a transaction and is later served
outside a transaction context (and vice-versa).
The solution is to take into account the transaction status when
storing in and serving from the query cache.
The query cache module did not check for the SQL_NO_CACHE keyword before
attempting to query the hash lookup table. This had a small performance impact.
By introducing a check on the query string before obtaining the hash mutex
we can gain some performance if the SQL_NO_CACHE directive is used often.
"pthread_mutex_trylock" isn't implemented correctly for the Windows platform.
This temporary patch reverts the patch for bug#21074 for Windows until
pthread_mutex_trylock is properly implemented.
Invaldating a subset of a sufficiently large query cache can take a long time.
During this time the server is efficiently frozen and no other operation can
be executed. This patch addresses this problem by setting a time limit on
how long time a dictionary access request can take before giving up on the
attempt. This patch does not work for query cache invalidations issued by
DROP, ALTER or RENAME TABLE operations.
Killing a SELECT query with KILL QUERY or KILL CONNECTION
causes a server crash if the query cache is enabled.
Normal evaluation of a query may be interrupted by the
KILL QUERY/CONNECTION statement, in this case the mysql_execute_command
function returns TRUE, and the thd->killed flag has true value.
In this case the result of the query may
be cached incompletely (omitting call to query_cache_insert inside
the net_real_write function), and next call to query_cache_end_of_result
may lead to server crash.
Thus, the query_cache_end_of_result function has been modified to abort
query cache in the case of killed thread.
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.
to a single statement.
---
Bug#24795: SHOW PROFILE
Profiling is only partially functional on some architectures. Where
there is no getrusage() system call, presently Null values are
returned where it would be required. Notably, Windows needs some love
applied to make it as useful.
Syntax this adds:
SHOW PROFILES
SHOW PROFILE [types] [FOR QUERY n] [OFFSET n] [LIMIT n]
where "n" is an integer
and "types" is zero or many (comma-separated) of
"CPU"
"MEMORY" (not presently supported)
"BLOCK IO"
"CONTEXT SWITCHES"
"PAGE FAULTS"
"IPC"
"SWAPS"
"SOURCE"
"ALL"
It also adds a session variable (boolean) "profiling", set to "no"
by default, and (integer) profiling_history_size, set to 15 by
default.
This patch abstracts setting THDs' "proc_info" behind a macro that
can be used as a hook into the profiling code when profiling
support is compiled in. All future code in this line should use
that mechanism for setting thd->proc_info.
---
Tests are now set to omit the statistics.
---
Adds an Information_schema table, "profiling" for access to
"show profile" data.
---
Merge zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-community-3--bug24795
into zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-community
---
Fix merge problems.
---
Fixed one bug in the query_source being NULL.
Updated test results.
---
Include more thorough profiling tests.
Improve support for prepared statements.
Use session-specific query IDs, starting at zero.
---
Selecting from I_S.profiling is no longer quashed in profiling, as
requested by Giuseppe.
Limit the size of captured query text.
No longer log queries that are zero length.
high load
MySQL server could crash if two or more threads would initiate query
cache resize at the moments very close in time.
The problem was introduced with the fix of bug 21051 in 5.0 and 5.1:
simultaneous query cache resizes would wait for the first one in
progress, but then each thread would try to finish the operation,
accessing the data that was already reset (attempt to dereference
'bins' pointer, which may be NULL already).
The solution is to check after synchronization if another thread has
done the reset already (test 'query_cache_size > 0' again).
No test case is provided because the bug is a subject to a race.
(Mostly in DBUG_PRINT() and unused arguments)
Fixed bug in query cache when used with traceing (--with-debug)
Fixed memory leak in mysqldump
Removed warnings from mysqltest scripts (replaced -- with #)
There were two problems: RESET QUERY CACHE took a long time to complete
and other threads were blocked during this time.
The patch does three things:
1 fixes a bug with improper use of test-lock-test_again technique.
AKA Double-Checked Locking is applicable here only in few places.
2 Somewhat improves performance of RESET QUERY CACHE.
Do my_hash_reset() instead of deleting elements one by one. Note
however that the slowdown also happens when inserting into sorted
list of free blocks, should be rewritten using balanced tree.
3 Makes RESET QUERY CACHE non-blocking.
The patch adjusts the locking protocol of the query cache in the
following way: it introduces a flag flush_in_progress, which is
set when Query_cache::flush_cache() is in progress. This call
sets the flag on enter, and then releases the lock. Every other
call is able to acquire the lock, but does nothing if
flush_in_progress is set (as if the query cache is disabled).
The only exception is the concurrent calls to
Query_cache::flush_cache(), that are blocked until the flush is
over. When leaving Query_cache::flush_cache(), the lock is
acquired and the flag is reset, and one thread waiting on
Query_cache::flush_cache() (if any) is notified that it may
proceed.
when high concurrency": remove HASH::current_record and make it
an external search parameter, so that it can not be the cause of a
race condition under high concurrent load.
The bug was in a race condition in table_hash_search,
when column_priv_hash.current_record was overwritten simultaneously
by multiple threads, causing the search for a suitable grant record
to fail.
No test case as the bug is repeatable only under concurrent load.
