Fixed error message when opening a not-MyISAM file.

tonu@x3.internalnet

Administrator@co3064164-a.

Administrator@co3064164-a.rochd1.qld.optushome.com.au

monty@tramp.mysql.fi

are things that are design-related.  @xref{Bugs}.

MySQL is written in multiple layers and different independent

modules.  These modules are listed below with an indication of how

modules.  Some of the new modules are listed below with an indication of how

well-tested each of them is:

@cindex modules, list of

@table @strong

@item The ISAM table handler --- Stable

This manages storage and retrieval of all data in MySQL Version 3.22

and earlier.  In all MySQL releases there hasn't been a single 

(reported) bug in this code. The only known way to get a corrupted table 

is to kill the server in the middle of an update.  Even that is unlikely 

to destroy any data beyond rescue, because all data are flushed to disk 

between each query.  There hasn't been a single bug report about lost data 

because of bugs in MySQL.

@cindex ISAM table handler

@cindex storing, data

@cindex retrieving, data

@cindex data, ISAM table handler

@item The MyISAM table handler --- Stable

This is new in MySQL Version 3.23.  It's largely based on the ISAM

table code but has a lot of new and very useful features.

@item The parser and lexical analyser --- Stable

There hasn't been a single reported bug in this system for a long time.

@item The C client code --- Stable

No known problems.  In early Version 3.20 releases, there were some limitations

in the send/receive buffer size.  As of Version 3.21, the buffer size is now

dynamic up to a default of 16M.

@item Standard client programs --- Stable

These include @code{mysql}, @code{mysqladmin}, @code{mysqlshow},

@code{mysqldump}, and @code{mysqlimport}.

@item Basic SQL --- Stable

The basic SQL function system and string classes and dynamic memory

handling.  Not a single reported bug in this system.

@item Query optimizer --- Stable

@item Range optimizer --- Stable

@item Join optimizer --- Stable

@item Locking --- Gamma

This is very system-dependent.  On some systems there are big problems

using standard OS locking (@code{fcntl()}).  In these cases, you should run the

to occur on some Linux systems, and on SunOS when using NFS-mounted file

systems.

@item Linux threads --- Stable

The major problem found has been with the @code{fcntl()} call, which is

fixed by using the @w{@code{--skip-locking}} option to

@code{mysqld}.  Some people have reported lockup problems with Version 0.5.

LinuxThreads will need to be recompiled if you plan to use

1000+ concurrent connections.  Although it is possible to run that many

connections with the default LinuxThreads (however, you will never go

above 1021), the default stack spacing of 2 MB makes the application

unstable, and we have been able to reproduce a coredump after creating

1021 idle connections.  @xref{Linux}.

@item Solaris 2.5+ pthreads --- Stable

We use this for all our production work.

@item MIT-pthreads (Other systems) --- Stable

There have been no reported bugs since Version 3.20.15 and no known bugs since

Version 3.20.16.  On some systems, there is a ``misfeature'' where some

operations are quite slow (a 1/20 second sleep is done between each query).

Of course, MIT-pthreads may slow down everything a bit, but index-based

@code{SELECT} statements are usually done in one time frame so there shouldn't

be a mutex locking/thread juggling.

@item Other thread implementions --- Beta - Gamma

The ports to other systems are still very new and may have bugs, possibly

in MySQL, but most often in the thread implementation itself.

@item @code{LOAD DATA ...}, @code{INSERT ... SELECT} --- Stable

Some people thought they had found bugs here, but these usually have

turned out to be misunderstandings.  Please check the manual before reporting

problems!

@item @code{ALTER TABLE} --- Stable

Small changes in Version 3.22.12.

@item DBD --- Stable

Now maintained by Jochen Wiedmann 

(@email{wiedmann@@neckar-alb.de}).  Thanks!

@item @code{mysqlaccess} --- Stable

Written and maintained by Yves Carlier 

(@email{Yves.Carlier@@rug.ac.be}). Thanks!

@item @code{GRANT} --- Stable

Big changes made in MySQL Version 3.22.12.

@item @strong{MyODBC} (uses ODBC SDK 2.5) --- Gamma

@item @strong{MyODBC 2.50} (uses ODBC SDK 2.5) --- Gamma

It seems to work well with some programs.

@item Replication -- Beta / Gamma

@item Replication -- Gamma

We are still working on replication, so don't expect this to be rock

solid yet.  On the other hand, some MySQL users are already

using this with good results.

@item BDB Tables -- Beta

@item BDB Tables -- Gamma

The Berkeley DB code is very stable, but we are still improving the interface

between MySQL and BDB tables, so it will take some time before this

is tested as well as the other table types.

@item InnoDB Tables -- Beta

@item InnoDB Tables -- Gamma

This is a recent addition to @code{MySQL}. They appear to work well and

can be used after some initial testing.

@item Automatic recovery of MyISAM tables - Beta

@item Automatic recovery of MyISAM tables - Gamma

This only affects the new code that checks if the table was closed properly

on open and executes an automatic check/repair of the table if it wasn't.

@item MERGE tables -- Beta / Gamma

The usage of keys on @code{MERGE} tables is still not well tested.  The

other parts of the @code{MERGE} code are quite well tested.

@item FULLTEXT -- Beta

Text search seems to work, but is still not widely used.

@item Bulk-insert - Alpha

New feature in MyISAM in MySQL 4.0 for faster insert of many rows.

@end table

MySQL AB provides high-quality support for paying customers, but the 

shell> mysqladmin -h 'your-host-name' variables

@end example

If you get @code{Errcode 13}, which means @code{Permission denied}, when

starting @code{mysqld} this means that you didn't have the right to

read/create files in the MySQL database or log directory. In this case

you should either start @code{mysqld} as the root user or change the

permissions for the involved files and directories so that you have the

right to use them. 

If @code{safe_mysqld} starts the server but you can't connect to it,

you should make sure you have an entry in @file{/etc/hosts} that looks like

this:

@item @code{max_allowed_packet}

The maximum size of one packet. The message buffer is initialized to

@code{net_buffer_length} bytes, but can grow up to @code{max_allowed_packet}

bytes when needed.  This value by default is small, to catch big (possibly

wrong) packets.  You must increase this value if you are using big

@code{BLOB} columns. It should be as big as the biggest @code{BLOB} you want

to use.  The current protocol limits @code{max_allowed_packet} to 16M.

@code{net_buffer_length} bytes, but can grow up to

@code{max_allowed_packet} bytes when needed.  This value by default is

small, to catch big (possibly wrong) packets.  You must increase this

value if you are using big @code{BLOB} columns. It should be as big as

the biggest @code{BLOB} you want to use.  The protocol limiits for

@code{max_allowed_packet} is 16M in MySQL 3.23 and 4G in MySQL 4.0.

@item @code{max_binlog_cache_size}

If a multi-statement transaction requires more than this amount of memory,

@cindex error messages, displaying

@cindex perror

@code{perror} can be used to print error message(s). @code{perror} can

be invoked like this:

@cindex errno

@cindex Errcode

For most system errors MySQL will, in addition to a internal text message,

also print the system error code in one of the following styles:

@code{message ... (errno: #)} or @code{message ... (Errcode: #)}.

You can find out what the error code means by either examining the

documentation for your system or use the @code{perror} utility.

@code{perror} prints a description for a system error code, or an MyISAM/ISAM

table handler error code.

@code{perror} is invoked like this:

@example

shell> perror [OPTIONS] [ERRORCODE [ERRORCODE...]]

For example:

Example:

shell> perror 64 79

shell> perror 13 64

Error code  13:  Permission decided

Error code  64:  Machine is not on the network

Error code  79:  Can not access a needed shared library

@end example

@code{perror} can be used to display a description for a system error

code, or an MyISAM/ISAM table handler error code. The error messages

are mostly system dependent.

Note that the error messages are mostly system dependent!

@node Batch Commands,  , perror, Client-Side Scripts

Constant expressions used by indexes are evaluated only once.

@item

@code{COUNT(*)} on a single table without a @code{WHERE} is retrieved

directly from the table information.  This is also done for any @code{NOT NULL}

expression when used with only one table.

directly from the table information for MyISAM and HEAP tables.  This is

also done for any @code{NOT NULL} expression when used with only one table.

@item

Early detection of invalid constant expressions. MySQL quickly

detects that some @code{SELECT} statements are impossible and returns no rows.

unnecessary @code{GROUP BY}'s.

@item

As soon as MySQL has sent the first @code{#} rows to the client, it

will abort the query.

will abort the query (If you are not using @code{SQL_CALC_FOUND_ROWS}).

@item

@code{LIMIT 0} will always quickly return an empty set.  This is useful

to check the query and to get the column types of the result columns.

higher speed by using the @code{INSERT DELAYED} statement. @xref{INSERT,

, @code{INSERT}}.

@item

Note that with @code{MyISAM} you can insert rows at the same time

Note that with @code{MyISAM} tables you can insert rows at the same time

@code{SELECT}s are running if there are no deleted rows in the tables.

@item

When loading a table from a text file, use @code{LOAD DATA INFILE}. This

flush-tables}.

@end enumerate

This procedure will be built into @code{LOAD DATA INFILE} in some future

version of MySQL.

Note that @code{LOAD DATA INFILE} also does the above optimization if

you insert into an empty table; The main difference with the above

procedure is that you can let myisamchk allocate much more temporary

memory for the index creation that you may want MySQL to allocate for

every index recreation.

Since @strong{MySQL 4.0} you can also use

@code{ALTER TABLE tbl_name DISABLE KEYS} instead of

@code{myisamchk -r -q /path/to/db/tbl_name}. This way you can also skip

@code{FLUSH TABLES} steps.

@item

You can speed up insertions by locking your tables:

You can speed up insertions that is done over multiple statements by

locking your tables:

@example

mysql> LOCK TABLES a WRITE;

statements. Locking is not needed if you can insert all rows with a single

statement.

For transactional tables, you should use @code{BEGIN/COMMIT} instead of

@code{LOCK TABLES} to get a speedup.

Locking will also lower the total time of multi-connection tests, but the

maximum wait time for some threads will go up (because they wait for

locks).  For example:

in the tables. In MySQL you can do this with the @code{EXPLAIN}

command. @xref{EXPLAIN, Explain, Explain, manual}.

@item

Try to avoid complex @code{SELECT} queries on tables that are updated a

Try to avoid complex @code{SELECT} queries on MyISAM tables that are updated a

lot. This is to avoid problems with table locking.

@item

The new @code{MyISAM} tables can insert rows in a table without deleted

  or	ADD [CONSTRAINT symbol] FOREIGN KEY index_name (index_col_name,...)

            [reference_definition]

  or    ALTER [COLUMN] col_name @{SET DEFAULT literal | DROP DEFAULT@}

  or    CHANGE [COLUMN] old_col_name create_definition

  or    MODIFY [COLUMN] create_definition

  or    CHANGE [COLUMN] old_col_name create_definition [FIRST | AFTER column_name]

  or    MODIFY [COLUMN] create_definition [FIRST | AFTER column_name]

  or    DROP [COLUMN] col_name

  or    DROP PRIMARY KEY

  or    DROP INDEX index_name

@node Packet too large, Communication errors, Out of memory, Common errors

@appendixsubsec @code{Packet too large} Error

A communication packet is a single SQL statement sent to the MySQL server

or a single row that is sent to the client.

When a MySQL client or the @code{mysqld} server gets a packet bigger

than @code{max_allowed_packet} bytes, it issues a @code{Packet too large}

error and closes the connection.

If you are using the @code{mysql} client, you may specify a bigger buffer by

starting the client with @code{mysql --set-variable=max_allowed_packet=8M}.

If you are using other clients that do not allow you to specify the maximum

packet size (such as @code{DBI}), you need to set the packet size when you

start the server.  You cau use a command-line option to @code{mysqld} to set

@code{max_allowed_packet} to a larger size.  For example, if you are

expecting to store the full length of a @code{BLOB} into a table, you'll need

to start the server with the @code{--set-variable=max_allowed_packet=16M}

option.

than @code{max_allowed_packet} bytes, it issues a @code{Packet too

large} error and closes the connection.  With some clients, you may also

get @code{Lost connection to MySQL server during query} error if the

communication packet is too big.

Note that both the client and the server has it's own

@code{max_allowed_packet} variable. If you want to handle big packets,

you have to increase this variable both in the client and in the server.

It's safe to increase this variable as memory is only allocated when

needed; This variable is more a precaution to catch wrong packets

between the client/server and also to ensure that you don't accidently

use big packets so that you run out of memory.

If you are using the @code{mysql} client, you may specify a bigger

buffer by starting the client with @code{mysql --set-variable=max_allowed_packet=8M}.  Other clients have different methods to set this variable.

You can use the option file to set @code{max_allowed_packet} to a larger

size in @code{mysqld}.  For example, if you are expecting to store the

full length of a @code{MEDIUMBLOB} into a table, you'll need to start

the server with the @code{set-variable=max_allowed_packet=16M} option.

You can also get strange problems with large packets if you are using

big blobs, but you haven't given @code{mysqld} access to enough memory

@code{ulimit -d 256000} to the beginning of the @code{safe_mysqld} script

and restart @code{mysqld}.

@node Communication errors, Full table, Packet too large, Common errors

@appendixsubsec Communication Errors / Aborted Connection

@itemize @bullet

@item

Added boolean fulltext search code. It should be considered early alpha.

@item

Extended @code{MODIFY} and @code{CHANGE} in @code{ALTER TABLE} to accept

the @code{AFTER} keyword.

@end itemize

@node News-4.0.0,  , News-4.0.1, News-4.0.x

      my_errno=HA_ERR_RECORD_FILE_FULL;

      DBUG_RETURN(-1);

    }

    if (*length > MI_MAX_BLOCK_LENGTH)

      *length=MI_MAX_BLOCK_LENGTH;

    info->state->data_file_length+= *length;

    info->s->state.split++;

    info->update|=HA_STATE_WRITE_AT_END;

      next_filepos=info->s->state.dellink != HA_OFFSET_ERROR ?

	info->s->state.dellink : info->state->data_file_length;

    if (*flag == 0)				/* First block */

    {

      if (*reclength > MI_MAX_BLOCK_LENGTH)

      {

	head_length= 16;

	temp[0]=13;

	mi_int4store(temp+1,*reclength);

	mi_int3store(temp+4,length-head_length);

	mi_sizestore((byte*) temp+8,next_filepos);

      }

      else

      {

	head_length=5+8+long_block*2;

	temp[0]=5+(uchar) long_block;

	  mi_sizestore((byte*) temp+5,next_filepos);

	}

      }

    }

    else

    {

      head_length=3+8+long_block;

  }

  else

  {

    if (info->header[0] > 6)

    if (info->header[0] > 6 && info->header[0] != 13)

      return_val=BLOCK_SYNC_ERROR;

  }

  info->next_filepos= HA_OFFSET_ERROR; /* Dummy ifall no next block */

  info->next_filepos= HA_OFFSET_ERROR; /* Dummy if no next block */

  switch (info->header[0]) {

  case 0:

    info->filepos=filepos+4;

    return return_val | BLOCK_FIRST | BLOCK_LAST;

  case 13:

    info->rec_len=mi_uint4korr(header+1);

    info->block_len=info->data_len=mi_uint3korr(header+5);

    info->next_filepos=mi_sizekorr(header+8);

    info->second_read=1;

    info->filepos=filepos+16;

    return return_val | BLOCK_FIRST;

  case 3:

    info->rec_len=info->data_len=mi_uint2korr(header+1);

    info->block_len=info->rec_len+ (uint) header[3];

      DBUG_PRINT("error",("Wrong header in %s",name_buff));

      DBUG_DUMP("error_dump",(char*) share->state.header.file_version,

		head_length);

      my_errno=HA_ERR_CRASHED;

      my_errno=HA_ERR_WRONG_TABLE_DEF;

      goto err;

    }

    share->options= mi_uint2korr(share->state.header.options);

#define MI_DYN_MAX_BLOCK_LENGTH	((1L << 24)-4L)

#define MI_DYN_MAX_ROW_LENGTH	(MI_DYN_MAX_BLOCK_LENGTH - MI_SPLIT_LENGTH)

#define MI_DYN_ALIGN_SIZE	4	/* Align blocks on this */

#define MI_MAX_DYN_HEADER_BYTE	12	/* max header byte for dynamic rows */

#define MI_MAX_DYN_HEADER_BYTE	13	/* max header byte for dynamic rows */

#define MI_MAX_BLOCK_LENGTH	(((ulong) 1 << 24)-1)

#define MEMMAP_EXTRA_MARGIN	7	/* Write this as a suffix for file */