Merge

@c @synindex tp fn cp

@synindex cp fn

@iftex

@c Well this is normal in Europe. Maybe this shold go into the include.texi?

@c Well this is normal in Europe. Maybe this should go into the include.texi?

@afourpaper

@end iftex

@c Get version and other info

@end menu

@node caching

@chapter How do MySQL handle caching

@chapter How MySQL handles caching

MySQL has the following caches:

(Note that the some of the filename has wrong spelling of cache :)

(Note that the some of the filename have a wrong spelling of cache. :)

@itemize @bullet

@item Key cache

@item Heap table cache

Many use of GROUP BY or DISTINCT caches all found

rows in a HEAP table (this is a very quick, in memory table with hash index)

rows in a HEAP table (this is a very quick in-memory table with hash index)

@item Join row cache.

For every full join in a SELECT statement (a full join here means there

was no keys that one could use to find the next table in a list), the

were no keys that one could use to find the next table in a list), the

found rows are cached in a join cache.  One SELECT query can use many

join caches in the worst case.

@end itemize

@node flush tables

@chapter How do MySQL handle flush tables

@chapter How MySQL handles flush tables

@itemize @bullet

@item

@end itemize

@node Filesort

@chapter How do MySQL do sorting (filesort)

@chapter How MySQL does sorting (filesort)

- Read all rows according to key or by table-scanning.

- Store the sort-key in a buffer (sort_buffer).

- When the buffer gets full, run a qsort on it and store the result

  in a temporary file.  Save a pointer to the sorted block.

- Repeate the above until all rows has been read.

- Repeat the above until all rows have been read.

- Repeat the following until there is less than MERGEBUFF2 (15) blocks left.

  - Do a multi-merge of up to MERGEBUFF (7) regions to one block in

    another temporary file.  Repeat until all blocks from the first file

    is in the second file.

    are in the second file.

- On the last multi-merge, only the pointer to the row (last part of

  the sort-key) is written to a result file.

- Now the code in sql/records.cc will be used to read through the

- Now the code in sql/records.cc will be used to read through them

  in sorted order by using the row pointers in the result file.

  To optimize this, we read in a big block of row pointers, sort these

  and then we read the rows in the sorted order into a row buffer

@contents

@bye

Do text here do something ??

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

It seems to work well with some programs.

@item replication -- alpha

@item Replication -- Alpha

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

solid yet.  On the other hand, some @strong{MySQL} users are already

using this with good results...

@item BDB tables -- alpha

@item BDB Tables -- Alpha

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

between @strong{MySQL} and BDB tables, so it will take some time before this

is as tested as the other table types.

@subsection Alpha-DEC-Unix notes (Tru64)

If you are using egcs 1.1.2 on Digital UNIX, you should upgrade to gcc

2.95.2, as egcs has some bad bugs on DEC!

2.95.2, as egcs on DEC has some serious bugs!

When compiling threaded programs under Digital UNIX, the documentation

recommends using the @code{-pthread} option for @code{cc} and @code{cxx} and

@itemize @bullet

@item

DON'T EVER GIVE ANYBODY (BUT THE @strong{MySQL} ROOT USER) ACCESS TO THE

DON'T EVER GIVE ANYONE (EXCEPT THE @strong{MySQL} ROOT USER) ACCESS TO THE

mysql.user DATABASE!  The encrypted password is the real password in

@strong{MySQL}; If you know this for one user you can easily login as

him if you have access to his 'host'.

and other access privilege information.  (Passwords are stored

encrypted, so a malicious user cannot simply read them to know the plain

text password).  If they can access the @code{mysql.user} password

column, they can however use it to login into the @strong{MySQL} server

for the given user.  With sufficient privileges, the same use can

however replace a password with a different one.)

column, they can use it to login into the @strong{MySQL} server

for the given user.  With sufficient privileges, the same user can

replace a password with a different one.)

@end itemize

There are some things that you cannot do with the @strong{MySQL}

see.  Rather, the password supplied by a user who is attempting to

connect is encrypted (using the @code{PASSWORD()} function). The

encrypted password is then used when the client/server is checking if

the password is connect (This is done without the encrypted password

the password is correct (This is done without the encrypted password

ever traveling over the connection).  Note that from @strong{MySQL}'s

point of view the encrypted password is the REAL password, so you should

not give anyone access to it!  In particular, don't give normal users

@item

If you get an error message where the hostname is not shown or where the

host name is an IP, even if you try to connect with an hostname:

hostname is an IP, even if you try to connect with a hostname:

@example

shell> mysqladmin -u root -pxxxx -h some-hostname ver

@item

Try to find out what is wrong with your DNS server and fix this.

@item

Specify IP's instead of hostnames in the @code{MySQL} privilege tables.

Specify IPs instead of hostnames in the @code{MySQL} privilege tables.

@item

Start mysqld with @code{--skip-name-resolve}.

@item

If you make changes to the grant tables directly (using @code{INSERT} or

@code{UPDATE} statement) and your changes seem to be ignored, remember

that you must issue a @code{FLUSH PRIVILEGES} statement or execute a

@code{mysqladmin flush-privileges} command to cause the server to reread

@code{mysqladmin flush-privileges} command to cause the server to re-read

the privilege tables.  Otherwise your changes have no effect until the

next time the server is restarted.  Remember that after you set the

@code{root} password with an @code{UPDATE} command, you won't need to

specify it until after you flush the privileges, because the server

still won't know you've changed the password yet!

won't know you've changed the password yet!

@item

If you have access problems with a Perl, PHP, Python or ODBC program, try to

connect to the server with @code{mysql -u user_name db_name} or @code{mysql

-u user_name -pyour_pass db_name}.  If you are able to connect using the

@code{mysql} client, there is a problem with your program and not with the

access privileges.  (Notice that there is no space between @code{-p} and the

access privileges.  (Note that there is no space between @code{-p} and the

password; you can also use the @code{--password=your_pass} syntax to specify

the password.)

the password. If you use the @code{-p} option alone, MySQL will prompt you

for the password.)

@item

For testing, start the @code{mysqld} daemon with the

analogous to the way that @strong{MySQL} interprets @code{TIME} values

as representing elapsed time rather than as time of day.

Note that if you add/subtract a date value against something that

contains a time part, the date value will automaticly be converted to a

Note that if you add or subtract a date value against something that

contains a time part, the date value will be automatically converted to a

datetime value:

@example

if no @code{PRIMARY KEY} was specified explicitly.)

@item

If you are doing an @code{ALTER TABLE} on/to a @code{MyISAM} table,

all non unique index are created in a separate batch (like in @code{REPAIR}).

This should make @code{ALTER TABLE} much faster when you have many index.

If you use @code{ALTER TABLE} on a @code{MyISAM} table, all non-unique 

indexes are created in a separate batch (like in @code{REPAIR}).

This should make @code{ALTER TABLE} much faster when you have many indexes.

@item

@findex mysql_info()

has no way to stop transmission of the file in the middle of the operation,

so the default bahavior is the same as if @code{IGNORE} is specified.

If you are @code{LOAD DATA INFILE} to an empty @code{MyISAM} table,

all non unique index are created in a separate batch (like in @code{REPAIR}).

If you use @code{LOAD DATA INFILE} on an empty @code{MyISAM} table,

all non-unique indexes are created in a separate batch (like in @code{REPAIR}).

This normally makes @code{LOAD DATA INFILE} much faster when you have many

index.

indexes.

@code{LOAD DATA INFILE} is the complement of @code{SELECT ... INTO OUTFILE}.

@xref{SELECT, , @code{SELECT}}.

you are dumping a big database.

Note that if you are using a new copy of the @code{mysqldump} program

and is going to do a dump that will be read into a very old @code{MySQL}

and you are going to do a dump that will be read into a very old @code{MySQL}

server, you should not use the @code{--opt} or @code{-e} options.

@code{mysqldump} supports the following options:

@itemize @bullet

@item

If you are using Access 2000, you should get an install Microsoft MDAC from

If you are using Access 2000, you should get and install Microsoft MDAC from

@uref{http://www.microsoft.com/data/download_21242023.htm}.  This will

fix the bug in Access that when you export data to @strong{MySQL}, the

table and column names wasn't specified.

table and column names aren't specified.

@item

You should have a primary key in the table.

@item

@item @uref{http://www.mysql.com/Downloads/Contrib/mybackup}

@item @uref{http://www.mswanson.com/mybackup, mybackup home page}

Wrapper for mysqldump to backup all databases. By "Marc Swanson".

Wrapper for mysqldump to backup all databases. By Marc Swanson.

@end itemize

@appendixsec RPMs for common tools (Most are for RedHat 6.1)

@appendixsubsec Changes in release 3.23.23

@itemize @bullet

@item

Changed @code{ALTER TABLE} to create non unique index in a separate batch

(which should make @code{ALTER TABLE} much faster when you have many index)

Changed @code{ALTER TABLE} to create non-unique indexes in a separate batch

(which should make @code{ALTER TABLE} much faster when you have many indexes).

@item

Added delayed index handling to @code{LOAD DATA INFILE}, when you are

reading into an empty file.

@item

Fixed a bug with @code{DATE_ADD/DATE_SUB} where it returned a datetime instead

of a date.

datetime.

@item

Fixed a problem with the thread cache which made some threads show up as

@code{***DEAD***} in @code{SHOW PROCESSLIST}.

at the same time as concurrent inserts crash. This only affects systems

that don't have the @code{pthread_rwlock_rdlock} code.

@item

When deleting rows with a non-unique key in HEAP table, all rows wasn't 

When deleting rows with a non-unique key in a HEAP table, all rows weren't 

always deleted.

@item

Fixed the BDB tables works on part keys.

Fixed that BDB tables work on part keys.

@item

Added @code{CHANGE MASTER TO} command

@item

Fixed fatal bug in @code{LOAD TABLE FROM MASTER} that did not lock the table during index re-build

@item @code{LOAD DATA INFILE} broke replication if the database was excluded from replication 

@item More variables in @code{SHOW SLAVE STATUS} and @code{SHOW MASTER STATUS}

@item @code{SLAVE STOP} now will not return until the slave thread actually exits

@end itemize

@node News-3.23.22, News-3.23.21, News-3.23.23, News-3.23.x

Fixed that @code{lex_hash.h} is created properly for each @code{MySQL}

distribution.

@item

Fixed that @code{MASTER} and @code{COLLECTION} are not a reserved words.

Fixed that @code{MASTER} and @code{COLLECTION} are not reserved words.

@item

The log generated by @code{--slow-query-log} didn't contain the whole queries.

@item

Fixed memory leak in the client library when using @code{host=..} in the

@code{my.cnf} file.

@item

Optimized functions that manipulates the hours/minutes/seconds.

Optimized functions that manipulate the hours/minutes/seconds.

@item

Fixed bug when comparing the result of @code{DATE_ADD}/@code{DATE_SUB}

against a number

Fixed bug when comparing the result of @code{DATE_ADD()}/@code{DATE_SUB()}

against a number.

@item

Changed the meaning of @code{-F, --fast} for @code{myisamchk}. Added option

@code{-C, --check-only-changed} to @code{myisamchk}.

@item

Added @code{ANALYZE table_name} to update key statistics for tables.

@item

Changed binary items @code{0x...} to be default regarded as an integer

Changed binary items @code{0x...} to be default regarded as an integer.

@item

Fix for SCO and @code{SHOW PROCESSLIST}.

@item

@item

Fixed a newly introduced bug in @code{MyISAM}, where the index file couldn't

get bigger than 64M.

@item Added @code{SHOW MASTER STATUS} and @code{SHOW SLAVE STATUS}

@end itemize

@node News-3.23.21, News-3.23.20, News-3.23.22, News-3.23.x

@code{myisamchk} didn't correctly update row checksum when used with

@code{-ro} (This only gave an warning in subsequent runs).

@item

Fixed bug in @code{REPAIR TABLE} so that it works with tables without index.

Fixed bug in @code{REPAIR TABLE} so that it works with tables without indexes.

@item

Fixed buffer overrun in @code{DROP DATABASE}

@item

@item

Check if locked threads take any CPU.

@item

Fix configure so the one can compile all libraries (like @code{MyISAM})

Fix configure so that one can compile all libraries (like @code{MyISAM})

without threads.

@item

Change to use mkstemp() instead of tempnam() for system that supports the call.

SET table_field1=concatenate(text_field1, text_field2), table_field3=23

IGNORE text_field3

This can be used to skip over extra columns in the text file, update columns

This can be used to skip over extra columns in the text file, or update columns

based on expressions of the read data...

on the in-data and 

@end example

@item

@code{LOAD DATA INFILE 'file_name' INTO TABLE 'table_name' ERRORS TO err_table_name}

which would cause any errors/warnings to be logged into the err_table_name

This would cause any errors and warnings to be logged into the err_table_name

table. That table would have a structure like:

@example

thread_test.o:		thread_test.c

			$(COMPILE) -c @MT_INCLUDES@ $(INCLUDES) $<

# Don't update the files from bitkeeper

%::SCCS/s.%

case "$target_os" in

  sco3.2v5*) 

     CFLAGS="$CFLAGS -DSCO"

     CXXFLAGS="$CXXFLAGS -DSCO"

     LD='$(CC) $(CFLAGS)'

     case "$CFLAGS" in

       *-belf*) 

# generated by configure from the .h.in files

dist-hook:

	rm -f $(distdir)/mysql_version.h $(distdir)/my_config.h

# Don't update the files from bitkeeper

%::SCCS/s.%