Fixed a problem using LOCK TABLES and BDB tables

thread-safe version of the MySQL client library with the

@code{--with-thread-safe-client} configure options. This will create a

@code{libmysqlclient_r} library with which you should link your threaded

applications.  @xref{Thread-safe clients}.

applications.  @xref{Threaded clients}.

@item

Options that pertain to particular systems can be found in the

* C API datatypes::             C API Datatypes

* C API function overview::     C API Function Overview

* C API functions::             C API Function Descriptions

* C Thread functions::          

* C API problems::              Common questions and problems when using the C API

* Building clients::            Building Client Programs

* Thread-safe clients::         How to Make a Thread-safe Client

* Threaded clients::            How to Make a Threaded Client

@end menu

The C API code is distributed with MySQL. It is included in the

is closed, at which time client memory is reclaimed.

For programming with threads, consult the 'how to make a thread-safe

client' chapter. @xref{Thread-safe clients}.

client' chapter. @xref{Threaded clients}.

@node C API datatypes, C API function overview, C, C

when an error occurred and what it was.

@node C API functions, C API problems, C API function overview, C

@node C API functions, C Thread functions, C API function overview, C

@subsection C API Function Descriptions

@menu

@code{MYSQL_FIELD_OFFSET mysql_field_seek(MYSQL_RES *result, MYSQL_FIELD_OFFSET offset)}

* Thread-safe clients::         How to Make a Thread-safe Client

* Threaded clients::         How to Make a Threaded Client

@subsubheading Description

Sets the field cursor to the given offset.   The next call to

An unknown error occurred.

@end table

@node C Thread functions, C API problems, C API functions, C

@subsection C Threaded Function Descriptions

@node C API problems, Building clients, C API functions, C

You need to use the following functions when you want to create a

threaded client. @xref{Threaded clients}.

@menu

* my_init::                     

* my_thread_init()::            

* my_thread_end()::             

@end menu

@node my_init, my_thread_init(), C Thread functions, C Thread functions

@subsubsection @code{my_init()}

@findex @code{my_init()}

@subsubheading Description

This function needs to be called once in the program before calling any

MySQL function.  This initializes some global variables that MySQL

needs.  If you are using a thread safe client library, this will also

call @code{my_thread_init()} for this thread.

This is automaticly called by @code{mysql_init()}

and @code{mysql_connect()}.

@subsubheading Return Values

none.

@node my_thread_init(), my_thread_end(), my_init, C Thread functions

@subsubsection @code{my_thread_init()}

@findex @code{my_thread_init()}

@subsubheading Description

This function needs to be called for each created thread to initialize

thread specific variables.

This is automaticly called by @code{my_init()} and @code{mysql_connect()}.

@subsubheading Return Values

none.

@node my_thread_end(),  , my_thread_init(), C Thread functions

@subsubsection @code{my_thread_end()}

@findex @code{my_thread_end()}

@subsubheading Description

This function needs to be called before calling @code{pthread_exit()} to

freed memory allocated by @code{my_thread_init()}.

Note that this function is NOT invoked automaticly be the client

library!

@subsubheading Return Values

none.

@node C API problems, Building clients, C Thread functions, C

@subsection Common questions and problems when using the C API

@tindex @code{mysql_query()}

adding @code{-lm} to the end of the compile/link line.

@node Building clients, Thread-safe clients, C API problems, C

@node Building clients, Threaded clients, C API problems, C

@subsection Building Client Programs

@cindex client programs, building

files.

@node Thread-safe clients,  , Building clients, C

@subsection How to Make a Thread-safe Client

@node Threaded clients,  , Building clients, C

@subsection How to Make a Threaded Client

@cindex clients, thread-safe

@cindex thread-safe clients

@cindex clients, threaded

@cindex threaded clients

The client library is almost thread safe. The biggest problem is

that the subroutines in @file{net.c} that read from sockets are not

Newer binary distributions should have both a normal and a

thread-safe client library.

To get a really thread-safe client where you can interrupt the client

from other threads and set timeouts when talking with the MySQL

server, you should use the @code{-lmysys}, @code{-lstring}, and @code{-ldbug}

libraries and the @code{net_serv.o} code that the server uses.

To get a threaded client where you can interrupt the client from other

threads and set timeouts when talking with the MySQL server, you should

use the @code{-lmysys}, @code{-lstring}, and @code{-ldbug} libraries and

the @code{net_serv.o} code that the server uses.

If you don't need interrupts or timeouts, you can just compile a thread

safe client library @code{(mysqlclient_r)} and use this.  @xref{C,,

MySQL C API}.  In this case you don't have to worry about the

@code{net_serv.o} object file or the other MySQL libraries.

When using a threaded client and you want to use timeouts and interrupts,

you can make great use of the routines in the @file{thr_alarm.c} file.

If you are using routines from the @code{mysys} library, the only thing

you must remember is to call @code{my_init()} first!

When using a threaded client and you want to use timeouts and

interrupts, you can make great use of the routines in the

@file{thr_alarm.c} file.  If you are using routines from the

@code{mysys} library, the only thing you must remember is to call

@code{my_init()} first! @xref{C Thread functions}.

All functions except @code{mysql_real_connect()} are by default

thread safe.  The following notes describe how to compile a thread safe

establish and release a mutex lock.

@end itemize

You need to know the following if you have a thread that is calling

MySQL functions, but that thread has not created the connection to the

MySQL database:

When you call @code{mysql_init()} or @code{mysql_connect()}, MySQL will

create a thread specific variable for the thread that is used by the

debug library (among other things).

If you have in a thread call a MySQL function, before a thread has

called @code{mysql_init()} or @code{mysql_connect()}, the thread will

not have the necessary thread specific variables in place and you are

likely to end up with a core dump sooner or later.

The get things to work smoothly you have to do the following:

@enumerate

@item

Call @code{my_init()} at the start of your program if it calls

any other MySQL function before calling @code{mysql_real_connect()}.

@item

Call @code{my_thread_init()} in the thread handler before calling

any MySQL function.

@item

In the thread, call @code{my_thread_end()} before calling

@code{pthread_exit()}.  This will free the memory used by MySQL thread

specific variables.

@end enumerate

You may get some errors because of undefined symbols when linking your

client with @code{mysqlclient_r}. In most cases this is because you haven't

included the thread libraries on the link/compile line.

@node Cplusplus, Java, C, Clients

@section MySQL C++ APIs

threads to continue.

@end itemize

You need to know the following if you have a thread that is calling

MySQL functions, but that thread has not created the connection to the

MySQL database:

When you call @code{mysql_init()} or @code{mysql_connect()}, MySQL will

create a thread specific variable for the thread that is used by the

debug library (among other things).

If you have in a thread call a MySQL function, before a thread has

called @code{mysql_init()} or @code{mysql_connect()}, the thread will

not have the necessary thread specific variables in place and you are

likely to end up with a core dump sooner or later.

The get things to work smoothly you have to do the following:

@enumerate

@item

Call @code{my_init()} at the start of your program if it calls

any other MySQL function before calling @code{mysql_real_connect()}.

@item

Call @code{my_thread_init()} in the thread handler before calling

any MySQL function.

@item

In the thread, call @code{my_thread_end()} before calling

@code{pthread_exit()}.  This will free the memory used by MySQL thread

specific variables.

@end enumerate

Exceptions to the above behaveour is when you use @code{REPAIR} or

@code{OPTIMIZE} or when the indexes are created in a batch after an

@code{LOAD DATA INFILE} or after an @code{ALTER TABLE} statement.

@appendixsubsec Changes in release 3.23.42

@itemize @bullet

@item

Fixed a problem when using @code{LOCK TABLES} and @code{BDB} tables.

@item

Fixed problem with @code{REPAIR TABLE} on MyISAM tables with row lengths

between 65517 - 65520 bytes

@item

chomp($pwd = `pwd`); $pwd = "." if ($pwd eq '');

require "$pwd/bench-init.pl" || die "Can't read Configuration file: $!\n";

$create_loop_count=$opt_loop_count;

if ($opt_small_test)

{

  $opt_loop_count/=100;

  $create_loop_count/=1000;

}

$max_tables=min($limits->{'max_tables'},$opt_loop_count);

if ($opt_small_test)

{

  $max_tables=10;

}

print "Testing the speed of creating and droping tables\n";

print "Testing with $max_tables tables and $opt_loop_count loop count\n\n";

$loop_time=new Benchmark;

for ($i=1 ; $i <= $opt_loop_count ; $i++)

for ($i=1 ; $i <= $create_loop_count ; $i++)

{

  do_many($dbh,$server->create("bench_$i",

			       ["i int NOT NULL",

}

$end_time=new Benchmark;

print "Time for create+drop ($opt_loop_count): " .

print "Time for create+drop ($create_loop_count): " .

    timestr(timediff($end_time, $loop_time),"all") . "\n";

if ($opt_fast && defined($server->{vacuum}))

  DBUG_ENTER("close_thread_tables");

  if (thd->locked_tables)

  {

    ha_commit_stmt(thd);			// If select statement

    DBUG_VOID_RETURN;				// LOCK TABLES in use

  }

  TABLE *table,*next;

  bool found_old_table=0;