Write UNION() for MERGE tables

@code{MERGE} table, you are only dropping the @code{MERGE}

specification.

Note that @code{DELETE FROM merge_table} used without a @code{WHERE}

will only clear the mapping for the table, not delete everything in the

mapped tables. (We plan to fix this in 4.0).

With identical tables we mean that all tables are created with identical

column information.  You can't put a MERGE over tables where the columns

are packed differently or doesn't have exactly the same columns.

be very useful when you suspect an error in a client and want to know

exactly what @code{mysqld} thought the client send to it.

By default, the @code{mysql.server} script starts the @strong{MySQL}

server with the @code{-l} option.  If you need better performance when

you start using @strong{MySQL} in a production environment, you can

remove the @code{-l} option from @code{mysql.server} or change it to

@code{--log-binary}.

The entries in this log are written as @code{mysqld} receives the questions.

This may be different than the order in which the statements is executed.

This is in contrast to the update log and the binary log which is written

after the query is executed, but before any locks are released.

@cindex update log

@cindex files, update log

@node Update log, Binary log, Query log, Log files

rm hostname-old.log

@end example

By default, the @code{mysql.server} script starts the @strong{MySQL}

server with the @code{-l} option.  If you need better performance when

you start using @strong{MySQL} in a production environment, you can

remove the @code{-l} option from @code{mysql.server} or change it to

@code{--log-update}.

Update logging is smart because it logs only statements that really update

data. So an @code{UPDATE} or a @code{DELETE} with a @code{WHERE} that finds no

rows is not written to the log. It even skips @code{UPDATE} statements that

set a column to the value it already has.

The update logging is done immediately after a query completes but before

any locks are released or any commit is done. This ensures that the log

will be logged in the execution order.

If you want to update a database from update log files, you could do the

following (assuming your update logs have names of the form

@file{file_name.###}):

If you are using @code{BEGIN} or @code{SET AUTO_COMMIT=0}, you must use

the @strong{MySQL} binary log for backups instead of the old update log.

The binary logging is done immediately after a query completes but before

any locks are released or any commit is done. This ensures that the log

will be logged in the execution order.

All updates (@code{UPDATE}, @code{DELETE} or @code{INSERT}) that changes

a transactional table (like BDB tables) is cached until a @code{COMMIT}.

Any updates to a not transactional table is stored in the binary log at

more than @code{long_query_time} to execute. The time to get the initial

table locks are not counted as execution time.

The slow query log is logged after the query is executed and after all

locks has been released. This may be different than the order in which

the statements is executed.

If no file name is given, it defaults to the name of the host machine

suffixed with @code{-slow.log}. If a filename is given, but doesn't

contain a path, the file is written in the data directory.

@appendixsubsec Changes in release 3.23.34

@itemize @bullet

@item

@code{SHOW CREATE TABLE} now dumps the @code{UNION()} for @code{MERGE} tables.

@item

Fixed bug when replicating timestamps.

@item

Fixed bug in bi-directonal replication.

@item

Added the @code{INNOBASE} table handler and the @code{BDB} table handler

to the @strong{MySQL} source distribution.

@item

When using @code{SET CHARACTER SET}, one can't use translated

characters in database, table and column names.

@item

@code{DELETE FROM merge_table} used without a @code{WHERE}

will only clear the mapping for the table, not delete everything in the

mapped tables

@item

You cannot build in another directory when using

MIT-pthreads. Because this requires changes to MIT-pthreads, we are not

likely to fix this.

		   filename));

      if (check_param.testflag & (T_REP_BY_SORT | T_REP))

	VOID(fprintf(stderr,

		     "Try fixing it by using the --safe-recover (-o) option\n"));

		     "Try fixing it by using the --safe-recover (-o) or the --force (-f) option\n"));

    }

    else if (!(param->error_printed & 2) &&

	     !(param->testflag & T_FORCE_CREATE))

412

412

411

Table	Create Table

t3	CREATE TABLE `t3` (

  `a` int(11) NOT NULL default '0',

  `b` char(20) default NULL,

  KEY `a` (`a`)

) TYPE=MRG_MyISAM UNION=(t1,t2)

c

test1

test1

  MY_BASEDIR_VERSION=$MY_PWD		# Where bin, share and data are

  ledir=$MY_BASEDIR_VERSION/bin		# Where mysqld is

  DATADIR=$MY_BASEDIR_VERSION/data

  if test -z "defaults"

  then

    defaults="--defaults-extra-file=$MY_BASEDIR_VERSION/data/my.cnf"

  fi

# Check if this is a 'moved install directory'

elif test -f ./var/mysql/db.frm -a -f ./share/mysql/english/errmsg.sys -a \

 -x ./libexec/mysqld

  DBUG_RETURN(myrg_create(fn_format(buff,name,"","",2+4+16),

			  (const char **) table_names, (my_bool) 0));

}

void ha_myisammrg::append_create_info(String *packet)

{

  char buff[FN_REFLEN];

  packet->append(" UNION=(",8);

  MYRG_TABLE *table,*first;

  for (first=table=file->open_tables ; table != file->end_table ; table++)

  {

    char *name=table->table->s->filename;

    fn_format(buff,name,"","",3);

    if (table != first)

      packet->append(',');

    packet->append(buff,(uint) strlen(buff));

  }

  packet->append(')');

}