Re: Predicting mysqldump.exe output size
Posted by:
Rick James
Date: January 07, 2012 11:06AM
An INT (4 bytes on disk) may dump as "0," (2 bytes) or "-1222333444," (12 bytes).
An ENUM (1 byte on disk) may dump as '"female",' (9 bytes, while taking 1 byte on disk).
A VARCHAR(100) may dump as '"",' (3 bytes, while taking 1 byte on disk), or '"\"\\\"",' (9 bytes, while taking 4 bytes on disk)
A TIMESTAMP (4 bytes) or DATETIME (8 bytes) dumps as '"2012-01-07 09:00:09",' (22 bytes).
Etc.
No, 8/3 is not constant.
Other factors:
* (dump is smaller) InnoDB has more overhead on disk (2x-3x is a common rule of thumb)
* (dump is smaller) "free" space clutters disk, not the dump (but you are counting this)
* (dump is smaller) Indexes are not dumped (and should not be included in your equation).
* (dump is bigger) The dump (probably) includes the CREATE TABLE -- this is a couple hundred bytes that came mostly from the .frm file (which is usually 8K on disk). For small tables, this is a large 'percentage overhead' in the dump.
* etc.
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Re: Predicting mysqldump.exe output size
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