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How can I determine or estimate the size of the SQL dump file prior to using something like mysqldump?

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up vote 11 down vote accepted

Please run this query:

    Data_BB / POWER(1024,1) Data_KB,
    Data_BB / POWER(1024,2) Data_MB,
    Data_BB / POWER(1024,3) Data_GB
FROM (SELECT SUM(data_length) Data_BB FROM information_schema.tables
WHERE table_schema NOT IN ('information_schema','performance_schema','mysql')) A;

This will give you a ballpark figure. The column index_length is not used because mysqldump does not dump indexes, only data. Just to be safe, you should always gzip it immediately:

mysqldump --all-databases --routines --triggers | gzip > MySQLData.sql.gz

Give it a Try !!!

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Thanks. In my case, the query returned about 10.4 GB and the actual file size (not gzipped) turned out to be about 10.8 GB. – Micah Bolen Mar 20 '13 at 19:18
You are welcome – RolandoMySQLDBA Mar 20 '13 at 19:19
@RolandoMySQLDBA is there a way of getting an approximation of the gzipped size? – KalenGi Mar 1 at 1:22
@KalenGi Not easily, no. Compression ratio is a function of both the algorithm and the data being compressed. For example, the text "123123123..." repeating for 5GB is going to have a much higher compression ratio than 5GB of images. – christianbundy Jun 9 at 19:10

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