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Kirill Smelkov
mariadb
Commits
ed68d5a3
Commit
ed68d5a3
authored
Mar 14, 2002
by
unknown
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Massive cleanups to internals.texi.
Docs/internals.texi: Massive cleanups.
parent
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Docs/internals.texi
View file @
ed68d5a3
\input
texinfo @c -*-texinfo-*-
\input
texinfo @c -*-texinfo-*-
@c Copyright
1998
TcX AB, Detron HB and Monty Program KB
@c Copyright
2002 MySQL AB,
TcX AB, Detron HB and Monty Program KB
@c
@c
@c
%**start of header
@c
%**start of header
@setfilename internals.info
@setfilename internals.info
@c We want the types in the same index
@c We want the types in the same index
@c @synindex tp fn cp
@synindex cp fn
@synindex cp fn
@iftex
@iftex
@c Well this is normal in Europe. Maybe this should go into the include.texi?
@afourpaper
@afourpaper
@end iftex
@end iftex
@c Get version and other info
@c Get version and other info
@include include.texi
@include include.texi
@ifclear tex-debug
@ifclear tex-debug
@c This removes the black squares in the right margin
@c This removes the black squares in the right margin
@finalout
@finalout
@end ifclear
@end ifclear
@c Set background for HTML
@c Set background for HTML
@set
_
body
_
tags BGCOLOR=#FFFFFF TEXT=#000000 LINK=#101090 VLINK=#7030B0
@set
_
body
_
tags BGCOLOR=#FFFFFF TEXT=#000000 LINK=#101090 VLINK=#7030B0
@settitle @strong
{
MySQL
}
i
nternals Manual for version @value
{
mysql
_
version
}
.
@settitle @strong
{
MySQL
}
I
nternals Manual for version @value
{
mysql
_
version
}
.
@setchapternewpage o
ff
@setchapternewpage o
dd
@paragraphindent 0
@paragraphindent 0
@c
%**end of header
@c
%**end of header
@ifinfo
@ifinfo
...
@@ -35,67 +39,77 @@ END-INFO-DIR-ENTRY
...
@@ -35,67 +39,77 @@ END-INFO-DIR-ENTRY
@sp 10
@sp 10
@center @titlefont
{
@strong
{
MySQL
}
Internals Manual
}
@center @titlefont
{
@strong
{
MySQL
}
Internals Manual
}
@sp 10
@sp 10
@center Copyright @copyright
{}
1998 TcX AB, Detron HB and Monty Program KB
@center Copyright @copyright
{}
1998-2002 MySQL AB
@page
@end titlepage
@end titlepage
@node Top,
Introduction
, (dir), (dir)
@node Top,
caching
, (dir), (dir)
@ifinfo
@ifinfo
This is a manual about @strong
{
MySQL
}
internals.
This is a manual about @strong
{
MySQL
}
internals.
@end ifinfo
@end ifinfo
@menu
@menu
* caching:: How MySQL Handles Caching
* flush tables:: How MySQL Handles @code
{
FLUSH TABLES
}
* filesort:: How MySQL Does Sorting (@code
{
filesort
}
)
* coding guidelines:: Coding Guidelines
* mysys functions:: Functions In The @code
{
mysys
}
Library
* DBUG:: DBUG Tags To Use
* protocol:: MySQL Client/Server Protocol
@end menu
@end menu
@node caching,,,
@chapter How MySQL handles caching
@node caching, flush tables, Top, Top
@chapter How MySQL Handles Caching
@strong
{
MySQL
}
has the following caches:
@strong
{
MySQL
}
has the following caches:
(Note that the some of the filename have a wrong spelling of cache. :)
(Note that the some of the filename have a wrong spelling of cache. :)
@
itemize @bullet
@
table @strong
@item Key
c
ache
@item Key
C
ache
A shared cache for all B-tree index blocks in the different NISAM
A shared cache for all B-tree index blocks in the different NISAM
files. Uses hashing and reverse linked lists for quick caching of the
files. Uses hashing and reverse linked lists for quick caching of the
last used blocks and quick flushing of changed entries for a specific
last used blocks and quick flushing of changed entries for a specific
table. (@file
{
mysys/mf
_
keycash.c
}
)
table. (@file
{
mysys/mf
_
keycash.c
}
)
@item Record
c
ache
@item Record
C
ache
This is used for quick scanning of all records in a table.
This is used for quick scanning of all records in a table.
(@file
{
mysys/mf
_
iocash.c
}
and @file
{
isam/
_
cash.c
}
)
(@file
{
mysys/mf
_
iocash.c
}
and @file
{
isam/
_
cash.c
}
)
@item Table
c
ache
@item Table
C
ache
This holds the last used tables. (@file
{
sql/sql
_
base.cc
}
)
This holds the last used tables. (@file
{
sql/sql
_
base.cc
}
)
@item Hostname
c
ache
@item Hostname
C
ache
For quick lookup (with reverse name resolving). Is a must when one has a
For quick lookup (with reverse name resolving). Is a must when one has a
slow DNS.
slow DNS.
(@file
{
sql/hostname.cc
}
)
(@file
{
sql/hostname.cc
}
)
@item Privilege
c
ache
@item Privilege
C
ache
To allow quick change between databases the last used privileges are
To allow quick change between databases the last used privileges are
cached for each user/database combination.
cached for each user/database combination.
(@file
{
sql/sql
_
acl.cc
}
)
(@file
{
sql/sql
_
acl.cc
}
)
@item Heap
table c
ache
@item Heap
Table C
ache
Many use of
GROUP BY or DISTINCT caches all found
Many use of
@code
{
GROUP BY
}
or @code
{
DISTINCT
}
caches all found rows in
rows in a HEAP table (this is a very quick in-memory table with hash index
)
a @code
{
HEAP
}
table. (This is a very quick in-memory table with hash index.
)
@item Join
row cache.
@item Join
Row Cache
For every full join in a
SELECT statement (a full join here means there
For every full join in a
@code
{
SELECT
}
statement (a full join here means
were no keys that one could use to find the next table in a list), the
there were no keys that one could use to find the next table in a list),
found rows are cached in a join cache. One SELECT query can use many
the found rows are cached in a join cache. One @code
{
SELECT
}
query can
join caches in the worst case.
use many
join caches in the worst case.
@end
itemiz
e
@end
tabl
e
@node flush tables,,,
@chapter How MySQL handles flush tables
@node flush tables, filesort, caching, Top
@chapter How MySQL Handles @code
{
FLUSH TABLES
}
@itemize @bullet
@itemize @bullet
@item
@item
Flush tables is handled in @
cod
e
{
sql/sql
_
base.cc::close
_
cached
_
tables()
}
.
Flush tables is handled in @
fil
e
{
sql/sql
_
base.cc::close
_
cached
_
tables()
}
.
@item
@item
The idea of flush tables is to force all tables to be closed. This
The idea of flush tables is to force all tables to be closed. This
...
@@ -109,8 +123,8 @@ all tables)!
...
@@ -109,8 +123,8 @@ all tables)!
When one does a @code
{
FLUSH TABLES
}
, the variable @code
{
refresh
_
version
}
When one does a @code
{
FLUSH TABLES
}
, the variable @code
{
refresh
_
version
}
will be incremented. Every time a thread releases a table it checks if
will be incremented. Every time a thread releases a table it checks if
the refresh version of the table (updated at open) is the same as
the refresh version of the table (updated at open) is the same as
the current
refresh
_
version
. If not it will close it and broadcast
the current
@code
{
refresh
_
version
}
. If not it will close it and broadcast
a signal on
COND
_
refresh
(to wait any thread that is waiting for
a signal on
@code
{
COND
_
refresh
}
(to wait any thread that is waiting for
all instanses of a table to be closed).
all instanses of a table to be closed).
@item
@item
...
@@ -119,8 +133,8 @@ The current @code{refresh_version} is also compared to the open
...
@@ -119,8 +133,8 @@ The current @code{refresh_version} is also compared to the open
refresh version is different the thread will free all locks, reopen the
refresh version is different the thread will free all locks, reopen the
table and try to get the locks again; This is just to quickly get all
table and try to get the locks again; This is just to quickly get all
tables to use the newest version. This is handled by
tables to use the newest version. This is handled by
@
cod
e
{
sql/lock.cc::mysql
_
lock
_
tables()
}
and
@
fil
e
{
sql/lock.cc::mysql
_
lock
_
tables()
}
and
@
cod
e
{
sql/sql
_
base.cc::wait
_
for
_
tables()
}
.
@
fil
e
{
sql/sql
_
base.cc::wait
_
for
_
tables()
}
.
@item
@item
When all tables has been closed @code
{
FLUSH TABLES
}
will return an ok
When all tables has been closed @code
{
FLUSH TABLES
}
will return an ok
...
@@ -134,8 +148,8 @@ After this it will give other threads a chance to open the same tables.
...
@@ -134,8 +148,8 @@ After this it will give other threads a chance to open the same tables.
@end itemize
@end itemize
@node
Filesort,,,
@node
filesort, coding guidelines, flush tables, Top
@chapter How MySQL
does sorting (filesort
)
@chapter How MySQL
Does Sorting (@code
{
filesort
}
)
@itemize @bullet
@itemize @bullet
...
@@ -146,7 +160,7 @@ Read all rows according to key or by table scanning.
...
@@ -146,7 +160,7 @@ Read all rows according to key or by table scanning.
Store the sort-key in a buffer (@code
{
sort
_
buffer
}
).
Store the sort-key in a buffer (@code
{
sort
_
buffer
}
).
@item
@item
When the buffer gets full, run a
qsort
on it and store the result
When the buffer gets full, run a
@code
{
qsort
}
on it and store the result
in a temporary file. Save a pointer to the sorted block.
in a temporary file. Save a pointer to the sorted block.
@item
@item
...
@@ -174,8 +188,9 @@ and then we read the rows in the sorted order into a row buffer
...
@@ -174,8 +188,9 @@ and then we read the rows in the sorted order into a row buffer
@end itemize
@end itemize
@node Coding guidelines,,,
@chapter Coding guidelines
@node coding guidelines, mysys functions, filesort, Top
@chapter Coding Guidelines
@itemize @bullet
@itemize @bullet
...
@@ -225,23 +240,23 @@ Don't use two commands on the same line.
...
@@ -225,23 +240,23 @@ Don't use two commands on the same line.
Do not check the same pointer for @code
{
NULL
}
more than once.
Do not check the same pointer for @code
{
NULL
}
more than once.
@item
@item
Use long function and variable names in English
;
This makes your code
Use long function and variable names in English
.
This makes your code
easier to read.
easier to read.
@item
@item
Use
my
_
var as opposed to myVar or MyVar (@samp
{_}
rather than dancing SHIFT
Use
@code
{
my
_
var
}
as opposed to @code
{
myVar
}
or @code
{
MyVar
}
(@samp
{_}
to seperate words in identifiers).
rather than dancing SHIFT
to seperate words in identifiers).
@item
@item
Think assembly - make it easier for the compiler to optimize your code.
Think assembly - make it easier for the compiler to optimize your code.
@item
@item
Comment your code when you do something that someone else may think
Comment your code when you do something that someone else may think
is not
''
trivial''.
is not
``
trivial''.
@item
@item
Use @code
{
libstring
}
functions (in the
strings
directory)
Use @code
{
libstring
}
functions (in the
@file
{
strings
}
directory)
instead of standard
libc
string functions whenever possible.
instead of standard
@code
{
libc
}
string functions whenever possible.
@item
@item
Avoid using @code
{
malloc()
}
(its REAL slow); For memory allocations
Avoid using @code
{
malloc()
}
(its REAL slow); For memory allocations
...
@@ -268,26 +283,25 @@ Any @code{#define}'s are in all-caps.
...
@@ -268,26 +283,25 @@ Any @code{#define}'s are in all-caps.
Matching @samp
{
@
{}
are in the same column.
Matching @samp
{
@
{}
are in the same column.
@item
@item
Put the @samp
{
@
{}
after a 'switch' on the same line
Put the @samp
{
@
{}
after a @code
{
switch
}
on the same line, as this gives
better overall indentation for the switch statement:
@example
@example
switch (arg)
{
switch (arg)
{
@end example
@end example
Because this gives better overall indentation for the switch statement.
@item
@item
In all other cases, @
{
and @
}
should be on their own line, except
In all other cases, @
samp
{
@
{}
and @samp
{
@
}
}
should be on their own line, except
if there is nothing inside @
{
@
}
.
if there is nothing inside @
samp
{
@
{}
and @samp
{
@
}
}
.
@item
@item
Have a space after
'if'
Have a space after
@code
{
if
}
@item
@item
Put a space after
','
for function arguments
Put a space after
@samp
{
,
}
for function arguments
@item
@item
Functions return
0
on success, and non-zero on error, so you can do:
Functions return
@samp
{
0
}
on success, and non-zero on error, so you can do:
@example
@example
if(a() || b() || c())
{
error("something went wrong");
}
if(a() || b() || c())
{
error("something went wrong");
}
...
@@ -335,113 +349,110 @@ Suggested mode in emacs:
...
@@ -335,113 +349,110 @@ Suggested mode in emacs:
(setq c-default-style "MY")
(setq c-default-style "MY")
@end example
@end example
@node mysys functions,,,
@chapter mysys functions
@node mysys functions, DBUG, coding guidelines, Top
@chapter Functions In The @code
{
mysys
}
Library
Functions i mysys: (For flags se my
_
sys.h)
Functions in @code
{
mysys
}
: (For flags see @file
{
my
_
sys.h
}
)
int my
_
copy
_
A((const char *from,const char *to,myf MyFlags));
- Copy file
@table @code
@item int my
_
copy
_
A((const char *from, const char *to, myf MyFlags));
int my
_
delete
_
A((const char *name,myf MyFlags));
Copy file from @code
{
from
}
to @code
{
to
}
.
- Delete file
@item int my
_
delete
_
A((const char *name, myf MyFlags));
int my
_
getwd
_
A((string buf,uint size,myf MyFlags));
Delete file @code
{
name
}
.
int my
_
setwd
_
A((const char *dir,myf MyFlags));
- Get and set working directory
@item int my
_
getwd
_
A((string buf, uint size, myf MyFlags));
@item int my
_
setwd
_
A((const char *dir, myf MyFlags));
string my
_
tempnam
_
A((const char *pfx,myf MyFlags));
Get and set working directory.
- Make a uniq temp file name by using dir and adding something after
pfx to make name uniq. Name is made by adding a uniq 6 length-string
@item string my
_
tempnam
_
A((const char *pfx, myf MyFlags));
and TMP
_
EXT after pfx.
Make a unique temporary file name by using dir and adding something after
Returns pointer to malloced area for filename. Should be freed by
@code
{
pfx
}
to make name unique. The file name is made by adding a unique
free().
six character string and @code
{
TMP
_
EXT
}
after @code
{
pfx
}
.
Returns pointer to @code
{
malloc()
}
'ed area for filename. Should be freed by
File my
_
open
_
A((const char *FileName,int Flags,myf MyFlags));
@code
{
free()
}
.
File my
_
create
_
A((const char *FileName,int CreateFlags,
int AccsesFlags, myf MyFlags));
@item File my
_
open
_
A((const char *FileName,int Flags,myf MyFlags));
int my
_
close
_
A((File Filedes,myf MyFlags));
@item File my
_
create
_
A((const char *FileName, int CreateFlags, int AccsesFlags, myf MyFlags));
uint my
_
read
_
A((File Filedes,byte *Buffer,uint Count,myf MyFlags));
@item int my
_
close
_
A((File Filedes, myf MyFlags));
uint my
_
write
_
A((File Filedes,const byte *Buffer,uint Count,
@item uint my
_
read
_
A((File Filedes, byte *Buffer, uint Count, myf MyFlags));
myf MyFlags));
@item uint my
_
write
_
A((File Filedes, const byte *Buffer, uint Count, myf MyFlags));
ulong my
_
seek
_
A((File fd,ulong pos,int whence,myf MyFlags));
@item ulong my
_
seek
_
A((File fd,ulong pos,int whence,myf MyFlags));
ulong my
_
tell
_
A((File fd,myf MyFlags));
@item ulong my
_
tell
_
A((File fd,myf MyFlags));
- Use instead of open,open-with-create-flag, close read and write
Use instead of open, open-with-create-flag, close, read, and write
to get automatic error-messages (flag: MYF
_
WME) and only have
to get automatic error messages (flag @code
{
MYF
_
WME
}
) and only have
to test for != 0 if error (flag: MY
_
NABP).
to test for != 0 if error (flag @code
{
MY
_
NABP
}
).
int my
_
rename
_
A((const char *from,const char *to,myf MyFlags));
@item int my
_
rename
_
A((const char *from, const char *to, myf MyFlags));
- Rename file
Rename file from @code
{
from
}
to @code
{
to
}
.
FILE *my
_
fopen
_
A((const char *FileName,int Flags,myf MyFlags));
@item FILE *my
_
fopen
_
A((const char *FileName,int Flags,myf MyFlags));
FILE *my
_
fdopen
_
A((File Filedes,int Flags,myf MyFlags));
@item FILE *my
_
fdopen
_
A((File Filedes,int Flags,myf MyFlags));
int my
_
fclose
_
A((FILE *fd,myf MyFlags));
@item int my
_
fclose
_
A((FILE *fd,myf MyFlags));
uint my
_
fread
_
A((FILE *stream,byte *Buffer,uint Count,myf MyFlags));
@item uint my
_
fread
_
A((FILE *stream,byte *Buffer,uint Count,myf MyFlags));
uint my
_
fwrite
_
A((FILE *stream,const byte *Buffer,uint Count,
@item uint my
_
fwrite
_
A((FILE *stream,const byte *Buffer,uint Count, myf MyFlags));
myf MyFlags));
@item ulong my
_
fseek
_
A((FILE *stream,ulong pos,int whence,myf MyFlags));
ulong my
_
fseek
_
A((FILE *stream,ulong pos,int whence,myf MyFlags));
@item ulong my
_
ftell
_
A((FILE *stream,myf MyFlags));
ulong my
_
ftell
_
A((FILE *stream,myf MyFlags));
Same read-interface for streams as for files.
- Same read-interface for streams as for files
@item gptr
_
mymalloc
_
A((uint uSize,const char *sFile,uint uLine, myf MyFlag));
gptr
_
mymalloc
_
A((uint uSize,const char *sFile,
@item gptr
_
myrealloc
_
A((string pPtr,uint uSize,const char *sFile,uint uLine, myf MyFlag));
uint uLine, myf MyFlag));
@item void
_
myfree
_
A((gptr pPtr,const char *sFile,uint uLine));
gptr
_
myrealloc
_
A((string pPtr,uint uSize,const char *sFile,
@item int
_
sanity
_
A((const char *sFile,unsigned int uLine));
uint uLine, myf MyFlag));
@item gptr
_
myget
_
copy
_
of
_
memory
_
A((const byte *from,uint length,const char *sFile, uint uLine,myf MyFlag));
void
_
myfree
_
A((gptr pPtr,const char *sFile,uint uLine));
@code
{
malloc(size,myflag)
}
is mapped to these functions if not compiled
int
_
sanity
_
A((const char *sFile,unsigned int uLine));
with @code
{
-DSAFEMALLOC
}
.
gptr
_
myget
_
copy
_
of
_
memory
_
A((const byte *from,uint length,
const char *sFile, uint uLine,
@item void TERMINATE
_
A((void));
myf MyFlag));
Writes @code
{
malloc()
}
info on @code
{
stdout
}
if compiled with
- malloc(size,myflag) is mapped to this functions if not compiled
@code
{
-DSAFEMALLOC
}
.
with -DSAFEMALLOC
@item int my
_
chsize
_
A((File fd, ulong newlength, myf MyFlags));
void TERMINATE
_
A((void));
Change size of file @code
{
fd
}
to @code
{
newlength
}
.
- Writes malloc-info on stdout if compiled with -DSAFEMALLOC.
@item void my
_
error
_
D((int nr, myf MyFlags, ...));
int my
_
chsize
_
A((File fd,ulong newlength,myf MyFlags));
Writes message using error number (see @file
{
mysys/errors.h
}
) on @code
{
stdout
}
,
- Change size of file
or using curses, if @code
{
MYSYS
_
PROGRAM
_
USES
_
CURSES()
}
has been called.
void my
_
error
_
D((int nr,myf MyFlags, ...));
@item void my
_
message
_
A((const char *str, myf MyFlags));
- Writes message using error number (se mysys/errors.h) on
Writes @code
{
str
}
on @code
{
stdout
}
, or using curses, if
stdout or curses if MYSYS
_
PROGRAM
_
USES
_
CURSES() is called.
@code
{
MYSYS
_
PROGRAM
_
USES
_
CURSES()
}
has been called.
void my
_
message
_
A((const char *str,myf MyFlags));
@item void my
_
init
_
A((void ));
- Writes message-string on
Start each program (in @code
{
main()
}
) with this.
stdout or curses if MYSYS
_
PROGRAM
_
USES
_
CURSES() is called.
@item void my
_
end
_
A((int infoflag));
void my
_
init
_
A((void ));
Gives info about program.
- Start each program (in main) with this.
If @code
{
infoflag
&
MY
_
CHECK
_
ERROR
}
, prints if some files are left open.
void my
_
end
_
A((int infoflag));
If @code
{
infoflag
&
MY
_
GIVE
_
INFO
}
, prints timing info and malloc info
- Gives info about program.
about program.
- If infoflag
&
MY
_
CHECK
_
ERROR prints if some files are left open
- If infoflag
&
MY
_
GIVE
_
INFO prints timing info and malloc info
@item int my
_
redel
_
A((const char *from, const char *to, int MyFlags));
about prog.
Delete @code
{
from
}
before rename of @code
{
to
}
to @code
{
from
}
. Copies state
from old file to new file. If @code
{
MY
_
COPY
_
TIME
}
is set, sets old time.
int my
_
redel
_
A((const char *from, const char *to, int MyFlags));
- Delete from before rename of to to from. Copyes state from old
@item int my
_
copystat
_
A((const char *from, const char *to, int MyFlags));
file to new file. If MY
_
COPY
_
TIME is set sets old time.
Copy state from old file to new file. If @code
{
MY
_
COPY
_
TIME
}
is set,
sets old time.
int my
_
copystat
_
A((const char *from, const char *to, int MyFlags));
- Copye state from old file to new file.
@item string my
_
filename
_
A((File fd));
If MY
_
COPY
_
TIME is set sets copy also time.
Returns filename of open file.
string my
_
filename
_
A((File fd));
@item int dirname
_
A((string to, const char *name));
- Give filename of open file.
Copy name of directory from filename.
int dirname
_
A((string to,const char *name));
@item int test
_
if
_
hard
_
path
_
A((const char *dir
_
name));
- Copy name of directory from filename.
Test if @code
{
dir
_
name
}
is a hard path (starts from root).
int test
_
if
_
hard
_
path
_
A((const char *dir
_
name));
@item void convert
_
dirname
_
A((string name));
- Test if dirname is a hard path (Starts from root)
Convert dirname according to system.
In MSDOS, changes all characters to capitals and changes @samp
{
/
}
to @samp
{
\}
.
void convert
_
dirname
_
A((string name));
- Convert dirname acording to system.
@item string fn
_
ext
_
A((const char *name));
- In MSDOS changes all caracters to capitals and changes '/' to
Returns pointer to extension in filename.
'
\'
string fn
_
ext
_
A((const char *name));
@item string fn
_
format
_
A((string to,const char *name,const char *dsk,const char *form,int flag));
- Returns pointer to extension in filename
string fn
_
format
_
A((string to,const char *name,const char *dsk,
const char *form,int flag));
format a filename with replace of library and extension and
format a filename with replace of library and extension and
converts between different systems.
converts between different systems.
params to and name may be identicall
params to and name may be identicall
...
@@ -455,60 +466,93 @@ Functions i mysys: (For flags se my_sys.h)
...
@@ -455,60 +466,93 @@ Functions i mysys: (For flags se my_sys.h)
"open(fn
_
format(temp
_
buffe,name,"","",4),...)" to unpack home and
"open(fn
_
format(temp
_
buffe,name,"","",4),...)" to unpack home and
convert filename to system-form.
convert filename to system-form.
string fn
_
same
_
A((string toname,const char *name,int flag));
@item string fn
_
same
_
A((string toname, const char *name, int flag));
- Copys directory and extension from name to toname if neaded.
Copys directory and extension from @code
{
name
}
to @code
{
toname
}
if neaded.
copy can be forced by same flags that in fn
_
format.
Copying can be forced by same flags used in @code
{
fn
_
format()
}
.
@item int wild
_
compare
_
A((const char *str, const char *wildstr));
Compare if @code
{
str
}
matches @code
{
wildstr
}
. @code
{
wildstr
}
can contain
@samp
{
*
}
and @samp
{
?
}
as wildcard characters.
Returns 0 if @code
{
str
}
and @code
{
wildstr
}
match.
int wild
_
compare
_
A((const char *str,const char *wildstr));
@item void get
_
date
_
A((string to, int timeflag));
- Compare if str matches wildstr. Wildstr can contain "*" and "?"
Get current date in a form ready for printing.
as match-characters.
Returns 0 if match.
void get
_
date
_
A((string to,int timeflag));
@item void soundex
_
A((string out
_
pntr, string in
_
pntr))
- Get current date in a form ready for printing.
Makes @code
{
in
_
pntr
}
to a 5 char long string. All words that sound
alike have the same string.
void soundex
_
A((string out
_
pntr, string in
_
pntr))
@item int init
_
key
_
cache
_
A((ulong use
_
mem, ulong leave
_
this
_
much
_
mem));
- Makes in
_
pntr to a 5 chars long string. All words that sounds
Use caching of keys in MISAM, PISAM, and ISAM.
alike have the same string.
@code
{
KEY
_
CACHE
_
SIZE
}
is a good size.
Remember to lock databases for optimal caching.
int init
_
key
_
cache
_
A((ulong use
_
mem,ulong leave
_
this
_
much
_
mem));
@item void end
_
key
_
cache
_
A((void));
- Use cacheing of keys in MISAM, PISAM, and ISAM.
End key caching.
KEY
_
CACHE
_
SIZE is a good size.
- Remember to lock databases for optimal cacheing
void end
_
key
_
cache
_
A((void));
- End key-cacheing.
@node DBUG,
,,
@node DBUG,
protocol, mysys functions, Top
@chapter
The DBUG tags to use:
@chapter
DBUG Tags To Use
Here is some of the tags we now use:
Here is some of the tags we now use:
(We should probably add a couple of new ones)
(We should probably add a couple of new ones)
"enter" Arguments to the function.
@table @code
"exit" Results from the function.
@item enter
"info" is something that may be interesting.
Arguments to the function.
"warning" is when something doesn't go the usual route or may be wrong.
"error" when something went wrong.
@item exit
"loop" write in a loop, that is probably only useful when debugging
Results from the function.
the loop. These should normally be deleted when on is
satisfied with the code and it has been in real use for a while.
@item info
Something that may be interesting.
@item warning
When something doesn't go the usual route or may be wrong.
@item error
When something went wrong.
@item loop
Write in a loop, that is probably only useful when debugging
the loop. These should normally be deleted when one is
satisfied with the code and it has been in real use for a while.
@end table
Some specific to mysqld, because we want to watch these carefully:
Some specific to mysqld, because we want to watch these carefully:
"trans" Starting/stopping transactions.
@table @code
"quit" 'info' when mysqld is preparing to die.
@item trans
"query" Print query
Starting/stopping transactions.
@item quit
@code
{
info
}
when mysqld is preparing to die.
@item query
Print query.
@end table
@node protocol,,,
@chapter MySQL client/server protocol
Raw packet without compression
@node protocol, , DBUG, Top
==============================
@chapter MySQL Client/Server Protocol
@menu
* raw packet without compression::
* raw packet with compression::
* basic packets::
* communication::
* fieldtype codes::
@end menu
@node raw packet without compression, raw packet with compression, protocol, protocol
@section Raw Packet Without Compression
@example
-------------------------------------------------
-------------------------------------------------
| Packet Length | Packet no | Data |
| Packet Length | Packet no | Data |
| 3 Bytes | 1 Byte | n Bytes |
| 3 Bytes | 1 Byte | n Bytes |
-------------------------------------------------
-------------------------------------------------
@end example
3 Byte packet length
3 Byte packet length
The length is calculated with int3store
The length is calculated with int3store
...
@@ -526,12 +570,15 @@ n Byte data
...
@@ -526,12 +570,15 @@ n Byte data
The packet length can be recalculated with:
The packet length can be recalculated with:
length = byte1 + (256 * byte2) + (256 * 256 * byte3)
length = byte1 + (256 * byte2) + (256 * 256 * byte3)
Raw packet with compression
@node raw packet with compression, basic packets, raw packet without compression, protocol
===========================
@section Raw Packet With Compression
@example
-----------------------------------------------------
-----------------------------------------------------
| Packet Length | Packet no | Uncomp. Packet Length |
| Packet Length | Packet no | Uncomp. Packet Length |
| 3 Bytes | 1 Byte | 3 Bytes |
| 3 Bytes | 1 Byte | 3 Bytes |
-----------------------------------------------------
-----------------------------------------------------
@end example
3 Byte packet length
3 Byte packet length
The length is calculated with int3store
The length is calculated with int3store
...
@@ -540,14 +587,23 @@ Raw packet with compression
...
@@ -540,14 +587,23 @@ Raw packet with compression
1 Byte packet no
1 Byte packet no
3 Byte uncompressed packet length
3 Byte uncompressed packet length
If compression is used the first 7 bytes of each paket
If compression is used the first 7 bytes of each packet
is the header of the paket.
is the header of the packet.
@node basic packets, communication, raw packet with compression, protocol
@section Basic Packets
@menu
* ok packet::
* error packet::
@end menu
@node ok packet, error packet, basic packets, basic packets
@subsection OK Packet
Basic packets
==============
OK-packet
For details see sql/net
_
pkg.cc
For details see sql/net
_
pkg.cc
function send
_
ok
function send
_
ok
@example
-------------------------------------------------
-------------------------------------------------
| Header | No of Rows | Affected Rows |
| Header | No of Rows | Affected Rows |
| | 1 Byte | 1-8 Byte |
| | 1 Byte | 1-8 Byte |
...
@@ -558,6 +614,7 @@ OK-packet
...
@@ -558,6 +614,7 @@ OK-packet
| Messagetext |
| Messagetext |
| n Byte |
| n Byte |
-------------------------------------------------
-------------------------------------------------
@end example
Header
Header
1 byte number of rows ? (always 0 ?)
1 byte number of rows ? (always 0 ?)
...
@@ -568,7 +625,11 @@ OK-packet
...
@@ -568,7 +625,11 @@ OK-packet
1-8 bytes length of message
1-8 bytes length of message
n bytes messagetext
n bytes messagetext
Error-packet
@node error packet, , ok packet, basic packets
@subsection Error Packet
@example
-------------------------------------------------
-------------------------------------------------
| Header | Statuscode | Error no |
| Header | Statuscode | Error no |
| | 1 Byte | 2 Byte |
| | 1 Byte | 2 Byte |
...
@@ -576,6 +637,7 @@ Error-packet
...
@@ -576,6 +637,7 @@ Error-packet
| Messagetext | 0x00 |
| Messagetext | 0x00 |
| n Byte | 1 Byte |
| n Byte | 1 Byte |
-------------------------------------------------
-------------------------------------------------
@end example
Header
Header
1 byte status code (0xFF = ERROR)
1 byte status code (0xFF = ERROR)
...
@@ -584,9 +646,8 @@ Error-packet
...
@@ -584,9 +646,8 @@ Error-packet
1 byte 0x00
1 byte 0x00
@node communication, fieldtype codes, basic packets, protocol
The communication
@section Communication
=================
> Packet from server to client
> Packet from server to client
< Paket from client tor server
< Paket from client tor server
...
@@ -677,9 +738,10 @@ The communication
...
@@ -677,9 +738,10 @@ The communication
n data
n data
Fieldtype Codes:
@node fieldtype codes, , communication, protocol
================
@section Fieldtype Codes
@example
display
_
length |enum
_
field
_
type |flags
display
_
length |enum
_
field
_
type |flags
----------------------------------------------------
----------------------------------------------------
Blob 03 FF FF 00 |01 FC |03 90 00 00
Blob 03 FF FF 00 |01 FC |03 90 00 00
...
@@ -698,7 +760,7 @@ Datetime 03 13 00 00 |01 0C |03 00 00 00
...
@@ -698,7 +760,7 @@ Datetime 03 13 00 00 |01 0C |03 00 00 00
Timestamp 03 0E 00 00 |01 07 |03 61 04 00
Timestamp 03 0E 00 00 |01 07 |03 61 04 00
Time 03 08 00 00 |01 0B |03 00 00 00
Time 03 08 00 00 |01 0B |03 00 00 00
Date 03 0A 00 00 |01 0A |03 00 00 00
Date 03 0A 00 00 |01 0A |03 00 00 00
@end example
@c The Index was empty, and ugly, so I removed it. (jcole, Sep 7, 2000)
@c The Index was empty, and ugly, so I removed it. (jcole, Sep 7, 2000)
...
...
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