Greetings, Nguyen.
Have you checked https://wiki.postgresql.org/wiki/Disk_Usage ?
You wrote 29.11.2018, 10:40:
> Hello Everyone,
> My name is Thuy.
> This matter is not bug, but I have a question as below. May you help me?
> How to calculate size of tables which are saved on disk?
> Based on my internet searching, how to calculate the length of the table based on the formula:
> 8KB × ceil(number of records / floor(floor(8KB × fillfactor - 24) / (28 + data length of 1 record)))
> Example:
> Column | Type |
> ----------+---------------+
> aid | integer |
> bid | integer |
> abalance | integer |
> filler | character(84) |
>
> data length of 1 record = aid(4 bytes) + bid(4 bytes) + abalance(4
> bytes) + filler(84 bytes + 1 byte) = 97 byte
> The data length of a record must be rounded to 8 bytes.
=>> Data length of 1 record is 104 bytes.
> Therefore, I think that 1 character is contained in 1 byte of memory.
> However, column "filler" can be input with 84 characters "a"
> (single byte) or 84 characters "あ" (double-byte)
> I don’t know why double-byte character can be contained in single byte character?
> Can you explain to me this question?
> Thank you in advance.
--
Kind regards,
Pavlo mailto:pavlo.golub@cybertec.at