Suppose I have three columns, A, B, C. They each have a range of x, y and z possible values respectively.
Does an index on all three columns have a size proportional to x * y * z?
No. The size of an INDEX is (roughly)
N * L + overhead
N = Number of rows in the entire table.
L = Length (in bytes) of the values in all the columns of the index, plus columns in the PRIMARY KEY.
overhead = various pointer, lengths, padding, etc
Example: CREATE TABLE ... id INT PRIMARY KEY, A INT, INDEX(A) ...
INT is a 4-byte datatype. It can hold more than 4 billion distinct values. If there are 100 rows in the table, let's look at the BTree holding the secondary INDEX(A).
N = 100
L = 4 + 4 -- that bytes, not billions of bytes
N * L = 800, but once the overhead is added, and use the blocking, it will take 16KB. (Note: InnoDB allocates data and indexes in "blocks" of 16KB.)
Now add to that table
city VARCHAR(100), -- average length 10 characters
INDEX(city, A)
N = 100 -- still assuming 100 rows
L = (2+10) + 4 + 4 = 16
total = again, only 1-2 blocks.
The (2+10): 2 for the "length" of the string; 10, on average, for the actual string. (In some cases, the "2" is really "1" and if you are using utf8, each character could be multiple bytes.)
If that table grows to 1 million rows, the index may take 50MB, a lot of it being unavoidable "overhead".
A major exception:
For InnoDB, the size of the PRIMARY KEY is virtually zero since it is "clustered" with the data. Actually, there is about 1% extra for the non-leaf nodes in that BTree and some 'overhead'.
I want to store ranges in an SQL table column.
For example ,
amount greater than 10000
amount greater than 20000
amount 20000 - 100000
amount 100001 - maxvalue
and then filter the rows with a query like ex.
where amount = 10010
where amount = 20500
where amount = 6235633
plz suggest how to handle with 2 columns low - high or suggest a more feasible solution
and how to store maximum unknown value
Create a table with nullable low and high fields.
Then you can select records like this:
SELECT *
FROM table1 t1
WHERE <?> BETWEEN IFNULL(t1.low, <min_value>) AND IFNULL(t2.high, <max_value>)
The condition could be set without min and max values:
WHERE <?> BETWEEN t1.low AND t2.high AND t1.low + t2.hight IS NOT NULL
OR <?> >= t1.low AND t1.high IS NULL
OR <?> <= t1.high AND t1.low IS NULL
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
I have a Table with 2 columns: 'Id' (datatype=INT) , 'Representation' (datatype=binary).
I want to store a hexadecimal value in the form of binary digits in the 'Representation' Column.
What is the Max number of Binary digits that i can store in the 'Representation' column ?
MySql
BINARY
The MySql docs on the binary data type, mention:
The permissible maximum length is the same for BINARY and VARBINARY as it is for CHAR and VARCHAR, except that the length for BINARY and VARBINARY is a length in bytes rather than in characters.
So binary is put on the same level as char, and varbinary as varchar.
The docs on the char data type, mention:
The length of a CHAR column is fixed to the length that you declare when you create the table. The length can be any value from 0 to 255.
So the maximum size for binary is therefore achieved with this:
CREATE TABLE mytable (
id int,
representation binary(255)
)
This corresponds to 255 bytes of data, which corresponds to 510 hexadecimal digits, or 2040 bits.
VARBINARY
The varbinary type can store up to 65,535 bytes, from which the sizes of the other columns must be subtracted. Again, this follows from the docs on varchar:
Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 65,535. The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used.
So let's say you would need room for about 500 bytes in other columns, then you could defined this table:
CREATE TABLE mytable (
id int, // takes 4 bytes
representation binary(65000),
// other fields come here, taking up less than 532 bytes
)
... you would have 65,000 bytes, i.e. 130,000 hexadecimal digits or 520,000 bits.
SQL Server Binary
The Transact-SQL docs on binary state:
binary [ ( n ) ]
Fixed-length binary data with a length of n bytes, where n is a value from 1 through 8,000. The storage size is n bytes.
This means that with this table definition:
CREATE TABLE mytable (
id int,
representation binary(8000)
)
... you can store 8,000 bytes, i.e. 16,000 hexadecimal digits or 64,000 bits.
Note that the limit for varbinary is the same. The following advise is given in the docs:
Use varbinary when the sizes of the column data entries vary considerably.
I understand that the maximum row limit in mysql is 65535, which is equal to (2 ^ 16) - 1. I also understand that it is bad database design to have extremely long rows like that. However, this is my schema
CREATE TABLE mytable(
a VARCHAR(20000),
b VARCHAR(20000),
c VARCHAR(20000),
d VARCHAR(5535)
) CHARACTER SET=latin1;
This is the output I get
Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs
Let's do the math again
20000 + 20000 + 20000 + 5535 = 65535
which is equal to and does not surpass the limit. For the record, the highest value for column d that works is 5526.
I do not understand where those additional 9 characters come from.
The size of VARCHAR is calculated like this:
len + 1 bytes if column is 0 – 255 bytes, len + 2 bytes if column may require more than 255 bytes
so
CREATE TABLE mytable(
a VARCHAR(20000), -- 20002
b VARCHAR(20000), -- 20002
c VARCHAR(20000), -- 20002
d VARCHAR(5535) -- 5537
) CHARACTER SET=latin1;-- 65543 !!!! 8 Bytes to much
see this https://mariadb.com/kb/en/mariadb/data-type-storage-requirements/
from: http://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html
row length = 1
+ (sum of column lengths)
+ (number of NULL columns + delete_flag + 7)/8
+ (number of variable-length columns)
Try change column type to VARCHAR (20000) NOT NULL