RE: PostgreSQL and mySQL database size question

OK, but that only accounts for 3.2MB of the extra 49.6MB used by PostgreSQL.

-----Original Message-----
From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
Sent: Friday, April 27, 2001 2:05 PM
To: ingham@erols.com
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] PostgreSQL and mySQL database size question



FAQ item 4.7 discusses table size computations.   My guess is that it is
the 36 bytes-per-row that is the problem.  Those bytes record the
visibility of the row for proper transactions semantics and MVCC.


> Bruce,
>
> I have your book right in front of me... do you have that information in
the
> book?  If not, I will take a look at the FAQ.  As for mySQL, here are the
> storage requirements:
>
> Storage requirements for numeric types
>
> Column type     Storage required
> TINYINT        1 byte
> SMALLINT        2 bytes
> MEDIUMINT        3 bytes
> INT            4 bytes
> INTEGER        4 bytes
> BIGINT        8 bytes
> FLOAT(X)        4 if X <= 24 or 8 if 25 <= X <= 53
> FLOAT            4 bytes
> DOUBLE        8 bytes
> DOUBLE PRECISION    8 bytes
> REAL            8 bytes
> DECIMAL(M,D)    M+2 bytes if D > 0, M+1 bytes if D = 0 (D+2, if M < D)
> NUMERIC(M,D)    M+2 bytes if D > 0, M+1 bytes if D = 0 (D+2, if M < D)
>
> Storage requirements for date and time types
>
> Column type        Storage required
> DATE            3 bytes
> DATETIME        8 bytes
> TIMESTAMP        4 bytes
> TIME            3 bytes
> YEAR            1 byte
>
> Storage requirements for string types
>
> Column type        Storage required
>
> CHAR(M)        M bytes, 1 <= M <= 255
> VARCHAR(M)        L+1 bytes, where L <= M and 1 <= M <= 255
> TINYBLOB,
> TINYTEXT        L+1 bytes, where L < 2^8
> BLOB, TEXT        L+2 bytes, where L < 2^16
> MEDIUMBLOB,
> MEDIUMTEXT        L+3 bytes, where L < 2^24
> LONGBLOB,
> LONGTEXT        L+4 bytes, where L < 2^32
> ENUM('value1','value2',...) 1 or 2 bytes, depending on the number of
> enumeration values (65535 values maximum)
> SET('value1','value2',...) 1, 2, 3, 4 or 8 bytes, depending on the number
of
> set members (64 members maximum)
>
> Fred
>
> -----Original Message-----
> From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
> Sent: Friday, April 27, 2001 1:48 PM
> To: ingham@erols.com
> Cc: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] PostgreSQL and mySQL database size question
>
>
> Did you see the FAQ items on estimating database sizes?  Does MySQL have
> less overhead per row?
>
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026