ASCII Code - The extended ASCII table

 ASCII stands for American Standard Code for Information Interchange. It's a 7-bit character code where every single bit represents a unique character. On this webpage you will find 8 bits, 256 characters, according to ISO 8859-1 and Microsoft® Windows Latin-1 increased characters, which is available in certain programs such as Microsoft Word.

ASCII control characters (character code 0-31) The first 32 characters in the ASCII-table are unprintable control codes and are used to control peripherals such as printers.

DEC OCT HEX BIN Symbol HTML Number HTML Name Description 0 000 00 00000000 NUL �   Null char 1 001 01 00000001 SOH    Start of Heading 2 002 02 00000010 STX    Start of Text 3 003 03 00000011 ETX    End of Text 4 004 04 00000100 EOT    End of Transmission 5 005 05 00000101 ENQ    Enquiry 6 006 06 00000110 ACK    Acknowledgment 7 007 07 00000111 BEL    Bell 8 010 08 00001000 BS    Back Space 9 011 09 00001001 HT 	   Horizontal Tab 10 012 0A 00001010 LF 
   Line Feed 11 013 0B 00001011 VT    Vertical Tab 12 014 0C 00001100 FF    Form Feed 13 015 0D 00001101 CR 
   Carriage Return 14 016 0E 00001110 SO    Shift Out / X-On 15 017 0F 00001111 SI    Shift In / X-Off 16 020 10 00010000 DLE    Data Line Escape 17 021 11 00010001 DC1    Device Control 1 (oft. XON) 18 022 12 00010010 DC2    Device Control 2 19 023 13 00010011 DC3    Device Control 3 (oft. XOFF) 20 024 14 00010100 DC4    Device Control 4 21 025 15 00010101 NAK    Negative Acknowledgement 22 026 16 00010110 SYN    Synchronous Idle 23 027 17 00010111 ETB    End of Transmit Block 24 030 18 00011000 CAN    Cancel 25 031 19 00011001 EM    End of Medium 26 032 1A 00011010 SUB    Substitute 27 033 1B 00011011 ESC    Escape 28 034 1C 00011100 FS    File Separator 29 035 1D 00011101 GS    Group Separator 30 036 1E 00011110 RS    Record Separator 31 037 1F 00011111 US    Unit Separator

ASCII printable characters (character code 32-127)

Codes 32-127 are common for all the different variations of the ASCII table, they are called printable characters, represent letters, digits, punctuation marks, and a few miscellaneous symbols. You will find almost every character on your keyboard. Character 127 represents the command DEL.

DEC	OCT	HEX	BIN	Symbol	HTML Number	HTML Name	Description
32	040	20	00100000		 		Space
33	041	21	00100001	!	!		Exclamation mark
34	042	22	00100010	"	"	"	Double quotes (or speech marks)
35	043	23	00100011	#	#		Number
36	044	24	00100100	$	$		Dollar
37	045	25	00100101	%	%		Procenttecken
38	046	26	00100110	&	&	&	Ampersand
39	047	27	00100111	'	'		Single quote
40	050	28	00101000	(	(		Open parenthesis (or open bracket)
41	051	29	00101001	)	)		Close parenthesis (or close bracket)
42	052	2A	00101010	*	*		Asterisk
43	053	2B	00101011	+	+		Plus
44	054	2C	00101100	,	,		Comma
45	055	2D	00101101	-	-		Hyphen
46	056	2E	00101110	.	.		Period, dot or full stop
47	057	2F	00101111	/	/		Slash or divide
48	060	30	00110000	0	0		Zero
49	061	31	00110001	1	1		One
50	062	32	00110010	2	2		Two
51	063	33	00110011	3	3		Three
52	064	34	00110100	4	4		Four
53	065	35	00110101	5	5		Five
54	066	36	00110110	6	6		Six
55	067	37	00110111	7	7		Seven
56	070	38	00111000	8	8		Eight
57	071	39	00111001	9	9		Nine
58	072	3A	00111010	:	:		Colon
59	073	3B	00111011	;	&#59;		Semicolon
60	074	3C	00111100	<	&#60;	&lt;	Less than (or open angled bracket)
61	075	3D	00111101	=	&#61;		Equals
62	076	3E	00111110	>	&#62;	&gt;	Greater than (or close angled bracket)
63	077	3F	00111111	?	&#63;		Question mark
64	100	40	01000000	@	&#64;		At symbol
65	101	41	01000001	A	&#65;		Uppercase A
66	102	42	01000010	B	&#66;		Uppercase B
67	103	43	01000011	C	&#67;		Uppercase C
68	104	44	01000100	D	&#68;		Uppercase D
69	105	45	01000101	E	&#69;		Uppercase E
70	106	46	01000110	F	&#70;		Uppercase F
71	107	47	01000111	G	&#71;		Uppercase G
72	110	48	01001000	H	&#72;		Uppercase H
73	111	49	01001001	I	&#73;		Uppercase I
74	112	4A	01001010	J	&#74;		Uppercase J
75	113	4B	01001011	K	&#75;		Uppercase K
76	114	4C	01001100	L	&#76;		Uppercase L
77	115	4D	01001101	M	&#77;		Uppercase M
78	116	4E	01001110	N	&#78;		Uppercase N
79	117	4F	01001111	O	&#79;		Uppercase O
80	120	50	01010000	P	&#80;		Uppercase P
81	121	51	01010001	Q	&#81;		Uppercase Q
82	122	52	01010010	R	&#82;		Uppercase R
83	123	53	01010011	S	&#83;		Uppercase S
84	124	54	01010100	T	&#84;		Uppercase T
85	125	55	01010101	U	&#85;		Uppercase U
86	126	56	01010110	V	&#86;		Uppercase V
87	127	57	01010111	W	&#87;		Uppercase W
88	130	58	01011000	X	&#88;		Uppercase X
89	131	59	01011001	Y	&#89;		Uppercase Y
90	132	5A	01011010	Z	&#90;		Uppercase Z
91	133	5B	01011011	[	&#91;		Opening bracket
92	134	5C	01011100	\	&#92;		Backslash
93	135	5D	01011101	]	&#93;		Closing bracket
94	136	5E	01011110	^	&#94;		Caret - circumflex
95	137	5F	01011111	_	&#95;		Underscore
96	140	60	01100000	`	&#96;		Grave accent
97	141	61	01100001	a	&#97;		Lowercase a
98	142	62	01100010	b	&#98;		Lowercase b
99	143	63	01100011	c	&#99;		Lowercase c
100	144	64	01100100	d	&#100;		Lowercase d
101	145	65	01100101	e	&#101;		Lowercase e
102	146	66	01100110	f	&#102;		Lowercase f
103	147	67	01100111	g	&#103;		Lowercase g
104	150	68	01101000	h	&#104;		Lowercase h
105	151	69	01101001	i	&#105;		Lowercase i
106	152	6A	01101010	j	&#106;		Lowercase j
107	153	6B	01101011	k	&#107;		Lowercase k
108	154	6C	01101100	l	&#108;		Lowercase l
109	155	6D	01101101	m	&#109;		Lowercase m
110	156	6E	01101110	n	&#110;		Lowercase n
111	157	6F	01101111	o	&#111;		Lowercase o
112	160	70	01110000	p	&#112;		Lowercase p
113	161	71	01110001	q	&#113;		Lowercase q
114	162	72	01110010	r	&#114;		Lowercase r
115	163	73	01110011	s	&#115;		Lowercase s
116	164	74	01110100	t	&#116;		Lowercase t
117	165	75	01110101	u	&#117;		Lowercase u
118	166	76	01110110	v	&#118;		Lowercase v
119	167	77	01110111	w	&#119;		Lowercase w
120	170	78	01111000	x	&#120;		Lowercase x
121	171	79	01111001	y	&#121;		Lowercase y
122	172	7A	01111010	z	&#122;		Lowercase z
123	173	7B	01111011	{	&#123;		Opening brace
124	174	7C	01111100	|	&#124;		Vertical bar
125	175	7D	01111101	}	&#125;		Closing brace
126	176	7E	01111110	~	&#126;		Equivalency sign - tilde
127	177	7F	01111111		&#127;		Delete

The extended ASCII codes (character code 128-255)

There are several different variations of the 8-bit ASCII table. The table below is according to ISO 8859-1, also called ISO Latin-1. Codes 129-159 contain the Microsoft® Windows Latin-1 extended characters.

DEC	OCT	HEX	BIN	Symbol	HTML Number	HTML Name	Description
128	200	80	10000000	€	€	€	Euro sign
129	201	81	10000001
130	202	82	10000010	‚	‚	‚	Single low-9 quotation mark
131	203	83	10000011	ƒ	ƒ	ƒ	Latin small letter f with hook
132	204	84	10000100	„	„	„	Double low-9 quotation mark
133	205	85	10000101	…	…	…	Horizontal ellipsis
134	206	86	10000110	†	†	†	Dagger
135	207	87	10000111	‡	‡	‡	Double dagger
136	210	88	10001000	ˆ	ˆ	ˆ	Modifier letter circumflex accent
137	211	89	10001001	‰	‰	‰	Per mille sign
138	212	8A	10001010	Š	Š	Š	Latin capital letter S with caron
139	213	8B	10001011	‹	‹	‹	Single left-pointing angle quotation
140	214	8C	10001100	Œ	Œ	Œ	Latin capital ligature OE
141	215	8D	10001101
142	216	8E	10001110	Ž	Ž		Latin captial letter Z with caron
143	217	8F	10001111
144	220	90	10010000
145	221	91	10010001	‘	‘	‘	Left single quotation mark
146	222	92	10010010	’	’	’	Right single quotation mark
147	223	93	10010011	“	“	“	Left double quotation mark
148	224	94	10010100	”	”	”	Right double quotation mark
149	225	95	10010101	•	•	•	Bullet
150	226	96	10010110	–	–	–	En dash
151	227	97	10010111	—	—	—	Em dash
152	230	98	10011000	˜	˜	˜	Small tilde
153	231	99	10011001	™	™	™	Trade mark sign
154	232	9A	10011010	š	š	š	Latin small letter S with caron
155	233	9B	10011011	›	›	›	Single right-pointing angle quotation mark
156	234	9C	10011100	œ	œ	œ	Latin small ligature oe
157	235	9D	10011101
158	236	9E	10011110	ž	ž		Latin small letter z with caron
159	237	9F	10011111	Ÿ	Ÿ	ÿ	Latin capital letter Y with diaeresis
160	240	A0	10100000		 	 	Non-breaking space
161	241	A1	10100001	¡	¡	¡	Inverted exclamation mark
162	242	A2	10100010	¢	¢	¢	Cent sign
163	243	A3	10100011	£	£	£	Pound sign
164	244	A4	10100100	¤	¤	¤	Currency sign
165	245	A5	10100101	¥	¥	¥	Yen sign
166	246	A6	10100110	¦	¦	¦	Pipe, Broken vertical bar
167	247	A7	10100111	§	§	§	Section sign
168	250	A8	10101000	¨	¨	¨	Spacing diaeresis - umlaut
169	251	A9	10101001	©	©	©	Copyright sign
170	252	AA	10101010	ª	ª	ª	Feminine ordinal indicator
171	253	AB	10101011	«	«	«	Left double angle quotes
172	254	AC	10101100	¬	¬	¬	Not sign
173	255	AD	10101101		­	­	Soft hyphen
174	256	AE	10101110	®	®	®	Registered trade mark sign
175	257	AF	10101111	¯	¯	¯	Spacing macron - overline
176	260	B0	10110000	°	°	°	Degree sign
177	261	B1	10110001	±	±	±	Plus-or-minus sign
178	262	B2	10110010	²	²	²	Superscript two - squared
179	263	B3	10110011	³	³	³	Superscript three - cubed
180	264	B4	10110100	´	´	´	Acute accent - spacing acute
181	265	B5	10110101	µ	µ	µ	Micro sign
182	266	B6	10110110	¶	¶	¶	Pilcrow sign - paragraph sign
183	267	B7	10110111	·	·	·	Middle dot - Georgian comma
184	270	B8	10111000	¸	¸	¸	Spacing cedilla
185	271	B9	10111001	¹	¹	¹	Superscript one
186	272	BA	10111010	º	º	º	Masculine ordinal indicator
187	273	BB	10111011	»	»	»	Right double angle quotes
188	274	BC	10111100	¼	¼	¼	Fraction one quarter
189	275	BD	10111101	½	½	½	Fraction one half
190	276	BE	10111110	¾	¾	¾	Fraction three quarters
191	277	BF	10111111	¿	¿	¿	Inverted question mark
192	300	C0	11000000	À	À	À	Latin capital letter A with grave
193	301	C1	11000001	Á	Á	Á	Latin capital letter A with acute
194	302	C2	11000010	Â	Â	Â	Latin capital letter A with circumflex
195	303	C3	11000011	Ã	Ã	Ã	Latin capital letter A with tilde
196	304	C4	11000100	Ä	Ä	Ä	Latin capital letter A with diaeresis
197	305	C5	11000101	Å	Å	Å	Latin capital letter A with ring above
198	306	C6	11000110	Æ	Æ	Æ	Latin capital letter AE
199	307	C7	11000111	Ç	Ç	Ç	Latin capital letter C with cedilla
200	310	C8	11001000	È	È	È	Latin capital letter E with grave
201	311	C9	11001001	É	É	É	Latin capital letter E with acute
202	312	CA	11001010	Ê	Ê	Ê	Latin capital letter E with circumflex
203	313	CB	11001011	Ë	Ë	Ë	Latin capital letter E with diaeresis
204	314	CC	11001100	Ì	Ì	Ì	Latin capital letter I with grave
205	315	CD	11001101	Í	Í	Í	Latin capital letter I with acute
206	316	CE	11001110	Î	Î	Î	Latin capital letter I with circumflex
207	317	CF	11001111	Ï	Ï	Ï	Latin capital letter I with diaeresis
208	320	D0	11010000	Ð	Ð	Ð	Latin capital letter ETH
209	321	D1	11010001	Ñ	Ñ	Ñ	Latin capital letter N with tilde
210	322	D2	11010010	Ò	Ò	Ò	Latin capital letter O with grave
211	323	D3	11010011	Ó	Ó	Ó	Latin capital letter O with acute
212	324	D4	11010100	Ô	Ô	Ô	Latin capital letter O with circumflex
213	325	D5	11010101	Õ	Õ	Õ	Latin capital letter O with tilde
214	326	D6	11010110	Ö	Ö	Ö	Latin capital letter O with diaeresis
215	327	D7	11010111	×	×	×	Multiplication sign
216	330	D8	11011000	Ø	Ø	Ø	Latin capital letter O with slash
217	331	D9	11011001	Ù	Ù	Ù	Latin capital letter U with grave
218	332	DA	11011010	Ú	Ú	Ú	Latin capital letter U with acute
219	333	DB	11011011	Û	Û	Û	Latin capital letter U with circumflex
220	334	DC	11011100	Ü	Ü	Ü	Latin capital letter U with diaeresis
221	335	DD	11011101	Ý	Ý	Ý	Latin capital letter Y with acute
222	336	DE	11011110	Þ	Þ	Þ	Latin capital letter THORN
223	337	DF	11011111	ß	ß	ß	Latin small letter sharp s - ess-zed
224	340	E0	11100000	à	à	à	Latin small letter a with grave
225	341	E1	11100001	á	á	á	Latin small letter a with acute
226	342	E2	11100010	â	â	â	Latin small letter a with circumflex
227	343	E3	11100011	ã	ã	ã	Latin small letter a with tilde
228	344	E4	11100100	ä	ä	ä	Latin small letter a with diaeresis
229	345	E5	11100101	å	å	å	Latin small letter a with ring above
230	346	E6	11100110	æ	æ	æ	Latin small letter ae
231	347	E7	11100111	ç	ç	ç	Latin small letter c with cedilla
232	350	E8	11101000	è	è	è	Latin small letter e with grave
233	351	E9	11101001	é	é	é	Latin small letter e with acute
234	352	EA	11101010	ê	ê	ê	Latin small letter e with circumflex
235	353	EB	11101011	ë	ë	ë	Latin small letter e with diaeresis
236	354	EC	11101100	ì	ì	ì	Latin small letter i with grave
237	355	ED	11101101	í	í	í	Latin small letter i with acute
238	356	EE	11101110	î	î	î	Latin small letter i with circumflex
239	357	EF	11101111	ï	ï	ï	Latin small letter i with diaeresis
240	360	F0	11110000	ð	ð	ð	Latin small letter eth
241	361	F1	11110001	ñ	ñ	ñ	Latin small letter n with tilde
242	362	F2	11110010	ò	ò	ò	Latin small letter o with grave
243	363	F3	11110011	ó	ó	ó	Latin small letter o with acute
244	364	F4	11110100	ô	ô	ô	Latin small letter o with circumflex
245	365	F5	11110101	õ	õ	õ	Latin small letter o with tilde
246	366	F6	11110110	ö	ö	ö	Latin small letter o with diaeresis
247	367	F7	11110111	÷	÷	÷	Division sign
248	370	F8	11111000	ø	ø	ø	Latin small letter o with slash
249	371	F9	11111001	ù	ù	ù	Latin small letter u with grave
250	372	FA	11111010	ú	ú	ú	Latin small letter u with acute
251	373	FB	11111011	û	û	û	Latin small letter u with circumflex
252	374	FC	11111100	ü	ü	ü	Latin small letter u with diaeresis
253	375	FD	11111101	ý	ý	ý	Latin small letter y with acute
254	376	FE	11111110	þ	þ	þ	Latin small letter thorn
255	377	FF	11111111	ÿ	ÿ	ÿ	Latin small letter y with diaeresis

The VLC media player not working (can not be run as root) | Backtrack 5

1. Open Konsole Terminal
2. Type

  cd /usr/bin/
  hexedit vlc

3. Press Tab -> Switch to ASCII
4. Press Ctrl+ S -> Search "geteuid"

Modify to "getppid"

5. Press Ctrl+ X -> Save

JavaScript - Example mm/dd/yyyy formatted dates | USA

// use a function for the exact format desired...
function MDYDateString(d){
  function pad(n){
    return n< 10? '0'+ n: n;
  }
  return pad(d.getUTCMonth()+ 1)+ '/'+ pad(d.getUTCDate())+ '/'+ d.getUTCFullYear();
}
// prints something like 12/20/2012
var d= new Date();
console.log(MDYDateString(d));

JavaScript - check starts with and ends with | test startsWith and endsWith

Add this functions to the String prototype:

if (typeof String.prototype.startsWith != 'function') {
  String.prototype.startsWith = function (str){
    return this.slice(0, str.length) == str;
  };
}

if (typeof String.prototype.endsWith != 'function') {
  String.prototype.endsWith = function (str){
    return this.slice(-str.length) == str;
  };
}

Then use it:

"Starts with JavaScript".startsWith("Starts"); // true
var foo= "Ends with JavaScript";
var bar= "JavaScript";
foo.startsWith(bar); // true

UnRar - extract files from rar archives | BackTrack 5

apt-get install unrar
unrar x file.rar path/

unrar --help

MySQL - ERROR 2002 (HY000): Can't connect to local MySQL server through socket | BackTrack 5

mysql -u root -p
****

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

mkdir /var/run/mysqld
touch /var/run/mysqld/mysqld.sock

chown -R mysql /var/run/mysqld

/etc/init.d/mysql restart

PHP string to time not working - Error/Problem

Replace the - to /

Google Chrome can not be run as root - BackTrack 5

Google Chrome can not be run as root.

Please start Google Chrome as a normal user. To run as root, you must specify an alternate --user-data-dir for storage of profile information.

1. Open Konsole Terminal

2. Type

  cd /opt/google/chrome/
  hexedit chrome

3. Press Tab -> Switch to ASCII

4. Press Ctrl+ S -> Search "geteuid"

  Modify to "getppid"

5. Press Ctrl+ X -> Save

Install Flash Player - BackTrack 5

• As you may have noticed Flash Player does not work on Backtrack 5, so in order to fix this we first need to remove the current flash player by issuing the following commands:

root@bt:~# apt-get purge flashplugin-nonfree flashplugin-installer gnash gnash-common mozilla-plugin-gnash swfdec-mozilla
root@bt:~# rm -f /usr/lib/firefox/plugins/*flash*
root@bt:~# rm -f /usr/lib/firefox-addons/plugins/*flash*
root@bt:~# rm -f /usr/lib/mozilla/plugins/*flash*
root@bt:~# rm -f ~/.mozilla/plugins/*flash*so
root@bt:~# rm -rfd /usr/lib/nspluginwrapper

• After removing flash we need to get the new flash player from the official website:

1. Flash x64 ONLY FOR x64.
2. Flash Player Download the .tar.gz file.

• We will begin with Flash Square, SKIP THIS if you aren't using an x64 version of BackTrack.

root@bt:~# tar xvfz flashplayer10_2_p3_64bit_linux_111710.tar.gz
root@bt:~# chown root:root libflashplayer.so
root@bt:~# chmod 644 libflashplayer.so
root@bt:~# cp -f libflashplayer.so /usr/lib/mozilla/plugins/
root@bt:~# rm -rf libflashplayer.so
root@bt:~# ln -s /usr/lib/mozilla/plugins/libflashplayer.so /usr/lib/firefox/plugins/

• Next up we will take care of the Flash Player:

root@bt:~# tar xvfz install_flash_player_10_linux.tar.gz
root@bt:~# mkdir ~/.mozilla/plugins
root@bt:~# mv -f libflashplayer.so ~/.mozilla/plugins/
root@bt:~# ln -s /usr/lib/mozilla/plugins/libflashplayer.so /usr/lib/firefox-addons/plugins/
root@bt:~# ln -s /usr/lib/mozilla/plugins/libflashplayer.so /usr/lib/xulrunner-addons/plugins/

• We can test if flash player works over here.

Extract tar gz files (.tar.gz) - Linux command

Extract the vtigercrm-5.4.0.tar.gz archive file to /var/www/

tar xvfz vtigercrm-5.4.0.tar.gz -C /var/www/

More:

man tar

Top 1000 SQL Performance Tips - Top10SQLPerformanceTips

Interactive session from MySQL Camp I:
Specific Query Performance Tips (see also database design tips for tips on indexes):

1. Use EXPLAIN to profile the query execution plan
2. Use Slow Query Log (always have it on!)
3. Don't use DISTINCT when you have or could use GROUP BY
4. Insert performance
   1. Batch INSERT and REPLACE
   2. Use LOAD DATA instead of INSERT
5. LIMIT m,n may not be as fast as it sounds. Learn how to improve it and read more about Efficient Pagination Using MySQL
6. Don't use ORDER BY RAND() if you have > ~2K records
7. Use SQL_NO_CACHE when you are SELECTing frequently updated data or large sets of data
8. Avoid wildcards at the start of LIKE queries
9. Avoid correlated subqueries and in select and where clause (try to avoid in)
10. No calculated comparisons -- isolate indexed columns
11. ORDER BY and LIMIT work best with equalities and covered indexes
12. Separate text/blobs from metadata, don't put text/blobs in results if you don't need them
13. Derived tables (subqueries in the FROM clause) can be useful for retrieving BLOBs without sorting them. (Self-join can speed up a query if 1st part finds the IDs and uses then to fetch the rest)
14. ALTER TABLE...ORDER BY can take data sorted chronologically and re-order it by a different field -- this can make queries on that field run faster (maybe this goes in indexing?)
15. Know when to split a complex query and join smaller ones
16. Delete small amounts at a time if you can
17. Make similar queries consistent so cache is used
18. Have good SQL query standards
19. Don't use deprecated features
20. Turning OR on multiple index fields (<5.0) into UNION may speed things up (with LIMIT), after 5.0 the index_merge should pick stuff up.
21. Don't use COUNT * on Innodb tables for every search, do it a few times and/or summary tables, or if you need it for the total # of rows, use SQL_CALC_FOUND_ROWS and SELECT FOUND_ROWS()
22. Use INSERT ... ON DUPLICATE KEY update (INSERT IGNORE) to avoid having to SELECT
23. use groupwise maximum instead of subqueries
24. Avoid using IN(...) when selecting on indexed fields, It will kill the performance of SELECT query.
25. Prefer using UNION ALL if you don't need to merge the result

Scaling Performance Tips:

1. Use benchmarking
2. isolate workloads don't let administrative work interfere with customer performance. (ie backups)
3. Debugging sucks, testing rocks!
4. As your data grows, indexing may change (cardinality and selectivity change). Structuring may want to change. Make your schema as modular as your code. Make your code able to scale. Plan and embrace change, and get developers to do the same.

Network Performance Tips:

1. Minimize traffic by fetching only what you need.
   1. Paging/chunked data retrieval to limit
   2. Don't use SELECT *
   3. Be wary of lots of small quick queries if a longer query can be more efficient
2. Use multi_query if appropriate to reduce round-trips
3. Use stored procedures to avoid bandwidth wastage

OS Performance Tips:

1. Use proper data partitions
   1. For Cluster. Start thinking about Cluster *before* you need them
2. Keep the database host as clean as possible. Do you really need a windowing system on that server?
3. Utilize the strengths of the OS
4. pare down cron scripts
5. create a test environment
6. source control schema and config files
7. for LVM innodb backups, restore to a different instance of MySQL so Innodb can roll forward
8. partition appropriately
9. partition your database when you have real data -- do not assume you know your dataset until you have real data
10. Reduce swappiness of your OS

MySQL Server Overall Tips:

1. innodb_flush_commit=0 can help slave lag
2. Optimize for data types, use consistent data types. Use PROCEDURE ANALYSE() to help determine the smallest data type for your needs.
3. use optimistic locking, not pessimistic locking. try to use shared lock, not exclusive lock. share mode vs. FOR UPDATE
4. if you can, compress text/blobs
5. compress static data
6. don't back up static data as often
7. enable and increase the query and buffer caches if appropriate
8. config params -- http://docs.cellblue.nl/2007/03/17/easy-mysql-performance-tweaks/ is a good reference
9. Config variables & tips:
   1. use one of the supplied config files
   2. key_buffer, unix cache (leave some RAM free), per-connection variables, innodb memory variables
   3. be aware of global vs. per-connection variables
   4. check SHOW STATUS and SHOW VARIABLES (GLOBAL|SESSION in 5.0 and up)
   5. be aware of swapping esp. with Linux, "swappiness" (bypass OS filecache for innodb data files, innodb_flush_method=O_DIRECT if possible (this is also OS specific))
   6. defragment tables, rebuild indexes, do table maintenance
   7. If you use innodb_flush_txn_commit=1, use a battery-backed hardware cache write controller
   8. more RAM is good so faster disk speed
   9. use 64-bit architectures
10. --skip-name-resolve
11. increase myisam_sort_buffer_size to optimize large inserts (this is a per-connection variable)
12. look up memory tuning parameter for on-insert caching
13. increase temp table size in a data warehousing environment (default is 32Mb) so it doesn't write to disk (also constrained by max_heap_table_size, default 16Mb)
14. Run in SQL_MODE=STRICT to help identify warnings
15. /tmp dir on battery-backed write cache
16. consider battery-backed RAM for innodb logfiles
17. use --safe-updates for client
18. Redundant data is redundant
19. Keep an eye on buffer pool and keybuffer hit rate

Storage Engine Performance Tips:

1. InnoDB ALWAYS keeps the primary key as part of each index, so do not make the primary key very large
2. Utilize different storage engines on master/slave ie, if you need fulltext indexing on a table.
3. BLACKHOLE engine and replication is much faster than FEDERATED tables for things like logs.
4. Know your storage engines and what performs best for your needs, know that different ones exist.
   1. ie, use MERGE tables ARCHIVE tables for logs
   2. Archive old data -- don't be a pack-rat! 2 common engines for this are ARCHIVE tables and MERGE tables
5. use row-level instead of table-level locking for OLTP workloads
6. try out a few schemas and storage engines in your test environment before picking one.

Database Design Performance Tips:

1. Design sane query schemas. don't be afraid of table joins, often they are faster than denormalization
2. Don't use boolean flags
3. Use Indexes
4. Don't Index Everything
5. Do not duplicate indexes
6. Do not use large columns in indexes if the ratio of SELECTs:INSERTs is low.
7. Split out large blob elements in InnoDB
8. be careful of redundant columns in an index or across indexes
9. Use a clever key and ORDER BY instead of MAX
10. Normalize first, and denormalize where appropriate.
11. Databases are not spreadsheets, even though Access really really looks like one. Then again, Access isn't a real database
12. use INET_ATON and INET_NTOA for IP addresses, not char or varchar
13. make it a habit to REVERSE() email addresses, so you can easily search domains (this will help avoid wildcards at the start of LIKE queries if you want to find everyone whose e-mail is in a certain domain)
14. A NULL data type can take more room to store than NOT NULL
15. Avoid NULL in index attributes. Use 0 instead
16. Storing flags in a database can slow down execution due to a bad cardinality. Try using bit flags
17. Don't store flags in a NULL and NOT NULL manner. Update from NULL -> 1 is slower than 0 -> 1
18. Choose appropriate character sets & collations -- UTF16 will store each character in 2 bytes, whether it needs it or not, latin1 is faster than UTF8.
19. Use Triggers wisely
20. Use delayed key wrote
21. use min_rows and max_rows to specify approximate data size so space can be pre-allocated and reference points can be calculated.
22. Use HASH indexing for indexing across columns with similar data prefixes
23. Use myisam_pack_keys for int data
24. be able to change your schema without ruining functionality of your code
25. segregate tables/databases that benefit from different configuration variables
26. Don't access the last key part in a where clause with =
27. Abuse the system for optimiization you're using with system dependant features like RTREE's for optimized range queries

Other:

1. Hire a MySQL (tm) Certified DBA
2. Know that there are many consulting companies out there that can help, as well as MySQL's Professional Services.
3. Read and post to MySQL Planet at http://www.planetmysql.org
4. Attend the yearly MySQL Conference and Expo or other conferences with MySQL tracks (link to the conference here)
5. Support your local User Group (link to forge page w/user groups here)

Authored by

Jay Pipes, Sheeri Kritzer, Bill Karwin, Ronald Bradford, Farhan "Frank Mash" Mashraqi, Taso Du Val, Ron Hu, Klinton Lee, Rick James, Alan Kasindorf, Eric Bergen, Robert Eisele, Kaj Arno, Joel Seligstein, Amy Lee, Sameer Joshi, Surat Singh Bhati

Where does Konqueror store its history, and how do I erase it?

There are several kinds of "history" stored by Konqueror.

• The location bar combobox items and completion: you can clear those with right-click, "Clear History".

• The history module in the sidebar: you can clear it with a right-click on one of the host names, and selecting "Clear History".

• The HTTP cache (known as "Temporary Internet Files" in other environments) can be cleared in the KControl module called "Cache", using the "Clear cache" button on the bottom right.

 File locations (~/.kde is only an indication. Your distributor, or $KDEHOME, could have modified that value) :

• Combobox items: ~/.kde/share/config/konq_history

• History module and combobox completion: ~/.kde/share/apps/konqueror/konq_history (binary file)

• HTTP cache: ~/.kde/share/cache/http/ (previously in ~/.kde/share/apps/kio_http/cache/)

Linux - Installation PHP Development Tools (PDT) Eclipse

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