存儲空間消耗磁盤比較 int varchar date
小結：
1、日期類型按照date存儲節省空間，僅3字節，而按照字符串型char 8字節 20190316 ， varchar 20190316 9字節；
2、對於小於32768的整數，按照smallint僅僅為2字節，較字符型節約空間；
3、時間戳 1552187447 用int ，而非char(12);整數ip，長ip，用bigint；能數字，不字符型；
2019-03-16 20190316
https://dev.mysql.com/doc/refman/8.0/en/integer-types.html
Table 11.1 Required Storage and Range for Integer Types Supported by MySQL
| Type | Storage (Bytes) | Minimum Value Signed | Minimum Value Unsigned | Maximum Value Signed | Maximum Value Unsigned |
|---|---|---|---|---|---|
TINYINT |
1 | -128 |
0 |
127 |
255 |
SMALLINT |
2 | -32768 |
0 |
32767 |
65535 |
MEDIUMINT |
3 | -8388608 |
0 |
8388607 |
16777215 |
INT |
4 | -2147483648 |
0 |
2147483647 |
4294967295 |
BIGINT |
8 | -263 |
0 |
263-1 |
264-1 |
>>> 2**32
4294967296
>>> 2**31
2147483648
>>>
>>> 2**15
32768
>>>
https://dev.mysql.com/doc/refman/8.0/en/char.html
| Value | CHAR(4) | Storage Required | VARCHAR(4) | Storage Required |
|---|---|---|---|---|
‘‘ |
‘ ‘ |
4 bytes | ‘‘ |
1 byte |
‘ab‘ |
‘ab ‘ |
4 bytes | ‘ab‘ |
3 bytes |
‘abcd‘ |
‘abcd‘ |
4 bytes | ‘abcd‘ |
5 bytes |
‘abcdefgh‘ |
‘abcd‘ |
4 bytes | ‘abcd‘ |
5 bytes |
The values shown as stored in the last row of the table apply only when not using strict mode; if MySQL is running in strict mode, values that exceed the column length are not stored, and an error results.
https://dev.mysql.com/doc/refman/8.0/en/storage-requirements.html#data-types-storage-reqs-date-time
Date and Time Type Storage Requirements
For TIME, DATETIME, and TIMESTAMP columns, the storage required for tables created before MySQL 5.6.4 differs from tables created from 5.6.4 on. This is due to a change in 5.6.4 that permits these types to have a fractional part, which requires from 0 to 3 bytes.
| Data Type | Storage Required Before MySQL 5.6.4 | Storage Required as of MySQL 5.6.4 |
|---|---|---|
YEAR |
1 byte | 1 byte |
DATE |
3 bytes | 3 bytes |
TIME |
3 bytes | 3 bytes + fractional seconds storage |
DATETIME |
8 bytes | 5 bytes + fractional seconds storage |
TIMESTAMP |
4 bytes | 4 bytes + fractional seconds storage |
As of MySQL 5.6.4, storage for YEAR and DATE remains unchanged. However, TIME, DATETIME, andTIMESTAMP are represented differently. DATETIME is packed more efficiently, requiring 5 rather than 8 bytes for the nonfractional part, and all three parts have a fractional part that requires from 0 to 3 bytes, depending on the fractional seconds precision of stored values.
| Fractional Seconds Precision | Storage Required |
|---|---|
| 0 | 0 bytes |
| 1, 2 | 1 byte |
| 3, 4 | 2 bytes |
| 5, 6 | 3 bytes |
For example, TIME(0), TIME(2), TIME(4), and TIME(6) use 3, 4, 5, and 6 bytes, respectively. TIME andTIME(0) are equivalent and require the same storage.
存儲空間消耗磁盤比較 int varchar date