I have a table post:
field | type
---------------------------------
id | int A_I P_K
title | varchar(300)
content | text
When I insert a row with content more than 15k words, my database just save 10k words and I lost 5k words.
How can I fixed this?
I'm using MySQL and PHP framework Laravel 5.1
If you read the MySQL docs on TEXT type—or any other data type—you can find the limitations of each type.
For example, TEXT specifically has a limit of around 65K, however this limit can be decreased depending on the character encoding (e.g. UTF-8 or other multibyte encodings), because it's calculated in bytes and not by character.
A TEXT column with a maximum length of 65,535 (216 − 1) characters. The effective maximum length is less if the value contains multibyte characters. Each TEXT value is stored using a 2-byte length prefix that indicates the number of bytes in the value.
An optional length M can be given for this type. If this is done, MySQL creates the column as the smallest TEXT type large enough to hold values M characters long.
So if your requirements exceed these limits you should pick a type that is equipped to handle larger payloads, like MEDIUMBLOB and LONGBLOB, which can handle up to 16M and 4G repsectively.
Type of field stored in database, gives you something like space in "tiny" workshop, laboratory, "medium" factory, "long" like a a large factory.
but choose wisely, because that "space" sometimes accupies much more resources than it is needed. Use Type of field for it's purpose.
Type | Maximum length
-----------+-------------------------------------
TINYTEXT | 255 (2^8 −1) bytes
TEXT | 65,535 (2^16−1) bytes = 64 KiB
MEDIUMTEXT | 16,777,215 (2^24−1) bytes = 16 MiB
LONGTEXT | 4,294,967,295 (2^32−1) bytes = 4 GiB
Instead of type -> TEXT ( 65535 characters )
use type -> MEDIUMTEXT ( witch can contain 16 Million Characters )
Related
What is the size of column of int(11) in mysql in bytes?
And Maximum value that can be stored in this columns?
An INT will always be 4 bytes no matter what length is specified.
TINYINT = 1 byte (8 bit)
SMALLINT = 2 bytes (16 bit)
MEDIUMINT = 3 bytes (24 bit)
INT = 4 bytes (32 bit)
BIGINT = 8 bytes (64 bit).
The length just specifies how many characters to pad when selecting data with the mysql command line client. 12345 stored as int(3) will still show as 12345, but if it was stored as int(10) it would still display as 12345, but you would have the option to pad the first five digits. For example, if you added ZEROFILL it would display as 0000012345.
... and the maximum value will be 2147483647 (Signed) or 4294967295 (Unsigned)
INT(x) will make difference only in term of display, that is to show the number in x digits, and not restricted to 11. You pair it using ZEROFILL, which will prepend the zeros until it matches your length.
So, for any number of x in INT(x)
if the stored value has less digits than x, ZEROFILL will prepend zeros.
INT(5) ZEROFILL with the stored value of 32 will show 00032
INT(5) with the stored value of 32 will show 32
INT with the stored value of 32 will show 32
if the stored value has more digits than x, it will be shown as it is.
INT(3) ZEROFILL with the stored value of 250000 will show 250000
INT(3) with the stored value of 250000 will show 250000
INT with the stored value of 250000 will show 250000
The actual value stored in database is not affected, the size is still the same, and any calculation will behave normally.
This also applies to BIGINT, MEDIUMINT, SMALLINT, and TINYINT.
According to here, int(11) will take 4 bytes of space that is 32 bits of space with 2^(31) = 2147483648 max value and -2147483648min value. One bit is for sign.
As others have said, the minumum/maximum values the column can store and how much storage it takes in bytes is only defined by the type, not the length.
A lot of these answers are saying that the (11) part only affects the display width which isn't exactly true, but mostly.
A definition of int(2) with no zerofill specified will:
still accept a value of 100
still display a value of 100 when output (not 0 or 00)
the display width will be the width of the largest value being output from the select query.
The only thing the (2) will do is if zerofill is also specified:
a value of 1 will be shown 01.
When displaying values, the column will always have a width of the maximum possible value the column could take which is 10 digits for an integer, instead of the miniumum width required to display the largest value that column needs to show for in that specific select query, which could be much smaller.
The column can still take, and show a value exceeding the length, but these values will not be prefixed with 0s.
The best way to see all the nuances is to run:
CREATE TABLE `mytable` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`int1` int(10) NOT NULL,
`int2` int(3) NOT NULL,
`zf1` int(10) ZEROFILL NOT NULL,
`zf2` int(3) ZEROFILL NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `mytable`
(`int1`, `int2`, `zf1`, `zf2`)
VALUES
(10000, 10000, 10000, 10000),
(100, 100, 100, 100);
select * from mytable;
which will output:
+----+-------+-------+------------+-------+
| id | int1 | int2 | zf1 | zf2 |
+----+-------+-------+------------+-------+
| 1 | 10000 | 10000 | 0000010000 | 10000 |
| 2 | 100 | 100 | 0000000100 | 100 |
+----+-------+-------+------------+-------+
This answer is tested against MySQL 5.7.12 for Linux and may or may not vary for other implementations.
What is the size of column of int(11) in mysql in bytes?
(11) - this attribute of int data type has nothing to do with size of column. It is just the display width of the integer data type. From 11.1.4.5. Numeric Type Attributes:
MySQL supports an extension for optionally specifying the display
width of integer data types in parentheses following the base keyword
for the type. For example, INT(4) specifies an INT with a display
width of four digits.
A good explanation for this can be found here
To summarize : The number N in int(N) is often confused by the maximum size allowed for the column, as it does in the case of varchar(N). But this is not the case with Integer data types- the number N in the parentheses is not the maximum size for the column, but simply a parameter to tell MySQL what width to display the column at when the table's data is being viewed via the MySQL console (when you're using the ZEROFILL attribute).
The number in brackets will tell MySQL how many zeros to pad incoming integers with. For example: If you're using ZEROFILL on a column that is set to INT(5) and the number 78 is inserted, MySQL will pad that value with zeros until the number satisfies the number in brackets. i.e. 78 will become 00078 and 127 will become 00127. To sum it up: The number in brackets is used for display purposes.
In a way, the number in brackets is kind of usless unless you're using the ZEROFILL attribute.
So the size for the int would remain same i.e., -2147483648 to 2147483648 for signed and 0 to 4294967295 for unsigned (~ 2.15 billions and 4.2 billions, which is one of the reasons why developers remain unaware of the story behind the Number N in parentheses, as it hardly affects the database unless it contains over 2 billions of rows), and in terms of bytes it would be 4 bytes.
For more information on Integer Types size/range, refer to MySQL Manual
In MySQL integer int(11) has size is 4 bytes which equals 32 bit.
Signed value is : -2^(32-1) to 0 to 2^(32-1)-1
= -2147483648 to 0 to 2147483647
Unsigned values is : 0 to 2^32-1
= 0 to 4294967295
Though this answer is unlikely to be seen, I think the following clarification is worth making:
the (n) behind an integer data type in MySQL is specifying the display width
the display width does NOT limit the length of the number returned from a query
the display width DOES limit the number of zeroes filled for a zero filled column so the total number matches the display width (so long as the actual number does not exceed the display width, in which case the number is shown as is)
the display width is also meant as a useful tool for developers to know what length the value should be padded to
A BIT OF DETAIL
the display width is, apparently, intended to provide some metadata about how many zeros to display in a zero filled number.
It does NOT actually limit the length of a number returned from a query if that number goes above the display width specified.
To know what length/width is actually allowed for an integer data type in MySQL see the list & link: (types: TINYINT, SMALLINT, MEDIUMINT, INT, BIGINT);
So having said the above, you can expect the display width to have no affect on the results from a standard query, unless the columns are specified as ZEROFILL columns
OR
in the case the data is being pulled into an application & that application is collecting the display width to use for some other sort of padding.
Primary Reference: https://blogs.oracle.com/jsmyth/entry/what_does_the_11_mean
according to this book:
MySQL lets you specify a “width” for integer types, such as INT(11).
This is meaningless for most applications: it does not restrict the
legal range of values, but simply specifies the number of characters
MySQL’s interactive tools will reserve for display purposes. For
storage and computational purposes, INT(1) is identical to INT(20).
I think max value of int(11) is 4294967295
4294967295 is the answer, because int(11) shows maximum of 11 digits IMO
When I first learnt about field types in MySQL I would define anything that was not a number as a VARCHAR and set the length to anything. 500 2000, but am I right in saying the maximum is actually 255?
If this is the case, why does MySQL let me define columns with much larger lengths and what is it actually doing? Will it allow larger lengths? Does it define the column / field as something else?
Any advice welcomed.
This behavior was changed after 5.0.3:
Values in VARCHAR columns are variable-length strings. The length can
be specified as a value from 0 to 255 before MySQL 5.0.3, and 0 to
65,535 in 5.0.3 and later versions. The effective maximum length of a
VARCHAR in MySQL 5.0.3 and later is subject to the maximum row size
(65,535 bytes, which is shared among all columns) and the character
set used.
From The CHAR and VARCHAR Types documentation reference.
The maximum is 65k
The CHAR and VARCHAR Types
It was 255 before 5.0.3, but now:
Values in VARCHAR columns are variable-length strings. The length can be
specified as a value from 0 to 65,535.
The documentation of 5.0.x shows the transition:
Values in VARCHAR columns are variable-length strings. The length can be
specified as a value from 0 to 255 before MySQL 5.0.3, and 0 to 65,535
in 5.0.3 and later versions.
ref: What is the maximum range of varchar in MySQL?
There is a difference between varchar(n) with values of n up to 255 and values larger than 255.
MySQL stores variable length strings by encoding the length of the string in the first one or two bytes. For values less than 256, MySQL uses one byte of overhead for the length. For values of n as 256 or greater, MySQL uses two bytes of overhead for the length.
Note that this is based on the definition of the column, not on the contents. So an empty string ('') could occupy 1 byte as a varchar(255) and 2 bytes as a varchar(256) (not counting space for storing NULL flags).
To refresh your member, one byte can store integers from 0 to 255, and two bytes can store from 0 to 65,535. This is where these limits come from.
MySQL explanation, click on the link for further information.
A VARCHAR(255) column can hold a string with a maximum length of 255 characters. Assuming that the column uses the latin1 character set (one byte per character), the actual storage required is the length of the string (L), plus one byte to record the length of the string. For the string 'abcd', L is 4 and the storage requirement is five bytes. If the same column is instead declared to use the ucs2 double-byte character set, the storage requirement is 10 bytes: The length of 'abcd' is eight bytes and the column requires two bytes to store lengths because the maximum length is greater than 255 (up to 510 bytes).
I have php script that inserts articles in mysql DB.
the field type in mysql is text.
now, when i insert an article larger than 32K, it is truncated to 32K only. what i know is the max size of text in mysql is 64K.
PS.: mysql version is 5.0.51a-24+lenny5
PHP version is: PHP 5.3.2-1ubuntu4.9
mysql: max_allowed_packet=16M
any idea of why does mysql truncate it or how to fix it??
** EDIT **
my character set is utf8
by selecting hex of this field i got 65768, and as you know every two hex digits represent one byte, and thus here the actual size is 65768/2=32884
mysql> select length(hex(body)), length(body) from articles where article_id=62727;
+-------------------+--------------+
| length(hex(body)) | length(body) |
+-------------------+--------------+
| 65768 | 32884 |
+-------------------+--------------+
Thanks for your help
The TEXT type has a length of 64k Bytes and not Characters, so if you use a character set using more than one byte per character, then this error may occur.
In your case the string is always truncated at 32k, it looks like that you are using a UTF-16 character set which requires two bytes per character.
You have two possibilities:
Use a single-byte character set
Use a larger column type
From: http://dev.mysql.com/doc/refman/5.0/en/string-type-overview.html
A TEXT column with a maximum length of 65,535 (2^16 – 1) characters.
The effective maximum length is less if the value contains multi-byte characters.
So the maximum length of 64k characters is only possible with a charset like ANSI. UTF-8, for example, uses more than one byte to encode a character and thus less text can be stored in 2^16 bytes.
This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
Importance of varchar length in MySQL table
When using VARCHAR (assuming this is the correct data type for a short string) does the size matter? If I set it to 20 characters, will that take up less space or be faster than 255 characters?
Yes, is matter when you indexing multiple columns.
Prefixes can be up to 1000 bytes long (767 bytes for InnoDB tables). Note that prefix limits are measured in bytes, whereas the prefix length in CREATE TABLE statements is interpreted as number of characters. Be sure to take this into account when specifying a prefix length for a column that uses a multi-byte character set.
source : http://dev.mysql.com/doc/refman/5.0/en/column-indexes.html
In a latin1 collation, you can only specify up 3 columns of varchar(255).
While can specify up to 50 columns for varchar(20)
In-directly, without proper index, it will slow-down query speed
In terms of storage, it does not make difference,
as varchar stand for variable-length strings
In general, for a VARCHAR field, the amount of data stored in each field determines its footprint on the disk rather than the maximum size (unlike a CHAR field which always has the same footprint).
There is an upper limit on the total data stored within all fields of an index of 900 bytes (900 byte index size limit in character length).
The larger you make the field, the more likely people will try to use for purposes other than what you intended - and the greater the screen real-estate required to show the value - so its good practice to try to pick the right size, rather than assuming that if you make it as large as possible it will save you having to revisit the design.
The actual differences are:
TINYTEXT and other TEXT fields are stored separately from in-memory row inside MySQL heap, whereas VARCHAR() fields add up to 64k limit (so you can have more than 64k in TINYTEXTs, whereas you won't with VARCHAR).
TINYTEXT and other 'blob-like' fields will force SQL layer (MySQL) to use on-disk temporary tables whenever they are used, whereas VARCHAR will be still sorted 'in memory' (though will be converted to CHAR for the full width).
InnoDB internally doesn't really care whether it is tinytext or varchar. It is very easy to verify, create two tables, one with VARCHAR(255), another with TINYINT, and insert a record to both. They both will take single 16k page - whereas if overflow pages are used, TINYTEXT table should show up as taking at least 32k in 'SHOW TABLE STATUS'.
I usually prefer VARCHAR(255) - they don't cause too much of heap fragmentation for single row, and can be treated as single 64k object in memory inside MySQL. On InnoDB size differences are negligible.
In the documentation of MySQL:
http://dev.mysql.com/doc/refman/5.0/en/char.html
You have a table that indicates the bytes of a VARCHAR(4) (vs a CHAR(4)).
A simple VARCHAR(4) without string, only 1 byte. Then, a simple VARCHAR(255) without string is 1byte. A VARCHAR(4) with 'ab' is 3 bytes, and a VARCHAR(255) with 'ab' is 3 bytes. It's the same, but with the lenght limit :)
This will have no effect on performance. In this case the constraint merely helps ensure data integrity.
If you set it to 20, it will save only the first 20 characters. So yes, it will take up less space than 255 characters :).
The required storage space for VARCHAR is as follows:
VARCHAR(L), VARBINARY(L) — L + 1 bytes if column values require 0 – 255 bytes, L + 2 bytes if values may require more than 255 bytes
So VARCHAR does only require the space for the string plus one or two additional bytes for the length of the string.
I'm developing a database driven website for a Chinese audience in PHP. The content is stored in the database as a longtext field.
I was wondering how can I be sure the data to be stored isn't truncated?
It depends on the characters' sizes and some configuration options.
LONGTEXT [CHARACTER SET charset_name]
[COLLATE collation_name]
A TEXT column with a maximum length of
4,294,967,295 or 4GB (2^32 – 1)
characters. The effective maximum
length is less if the value contains
multi-byte characters. The effective
maximum length of LONGTEXT columns
also depends on the configured maximum
packet size in the client/server
protocol and available memory. Each
LONGTEXT value is stored using a
four-byte length prefix that indicates
the number of bytes in the value.
http://dev.mysql.com/doc/refman/5.0/en/string-type-overview.html