Re: 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(at)candle(dot)pha(dot)pa(dot)us]
> Sent: Friday, April 27, 2001 1:48 PM
> To: ingham(at)erols(dot)com
> Cc: pgsql-general(at)postgresql(dot)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?
>
>

--
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