Thread: postgres 8.3 beta 2 storage question
Hi,
1.How does postgres version 8.3 betat 2 handle varchar and numeric data types in terms of storage
I understand for varchar it has 1byte overhead (instead of 4) if length<128
How does it handle for numeric? The manual says
"The actual storage requirement is two bytes for each group of four decimal digits, plus five to eight bytes overhead."
I dont understand how the overhead is measured here?...5 to 8 bytes?
2. Does postgres always inserts a complete record into a page unlike oracle whose record can span multiple pages? Does this waste space too?
Thanks
sharmila
1.How does postgres version 8.3 betat 2 handle varchar and numeric data types in terms of storage
I understand for varchar it has 1byte overhead (instead of 4) if length<128
How does it handle for numeric? The manual says
"The actual storage requirement is two bytes for each group of four decimal digits, plus five to eight bytes overhead."
I dont understand how the overhead is measured here?...5 to 8 bytes?
2. Does postgres always inserts a complete record into a page unlike oracle whose record can span multiple pages? Does this waste space too?
Thanks
sharmila
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> 1.How does postgres version 8.3 betat 2 handle varchar and numeric data
> types in terms of storage
> I understand for varchar it has 1byte overhead (instead of 4) if length<128
> How does it handle for numeric? The manual says
> "The actual storage requirement is two bytes for each group of four decimal
> digits, plus five to eight bytes overhead."
>which manual?
>( not these two: )
>http://www.postgresql.org/docs/8.1/static/datatype.html#DATATYPE-NUMERIC-DECIMAL
>http://www.postgresql.org/docs/8.2/static/datatype-numeric.html#DATATYPE-NUMERIC-DECIMAL
http://www.postgresql.org/docs/8.3/static/datatype-numeric.html
> 2. Does postgres always inserts a complete record into a page unlike oracle
> whose record can span multiple pages? Does this waste space too?
>records larger than one page are TOASTed
>http://www.postgresql.org/docs/current/static/storage-page-layout.html
Thanks
sharmila
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2007/11/27, SHARMILA JOTHIRAJAH <sharmi_jo@yahoo.com>: > 1.How does postgres version 8.3 betat 2 handle varchar and numeric data > types in terms of storage > I understand for varchar it has 1byte overhead (instead of 4) if length<128 > How does it handle for numeric? The manual says > "The actual storage requirement is two bytes for each group of four decimal > digits, plus five to eight bytes overhead." which manual? ( not these two: ) http://www.postgresql.org/docs/8.1/static/datatype.html#DATATYPE-NUMERIC-DECIMAL http://www.postgresql.org/docs/8.2/static/datatype-numeric.html#DATATYPE-NUMERIC-DECIMAL > 2. Does postgres always inserts a complete record into a page unlike oracle > whose record can span multiple pages? Does this waste space too? records larger than one page are TOASTed http://www.postgresql.org/docs/current/static/storage-page-layout.html -- Filip Rembiałkowski