Обсуждение: how to store more than 3 MB of character data in Postgres Varchar field

Hi,

We have  a requirement wherein we have to store around 3 MB of data in
Postgres database.

We had gone through the postgres website
http://www.postgresql.org/docs/7.4/interactive/datatype-character.html#DATATYPE-CHARACTER-SPECIAL-TABLE


The above link says "varchar" can store upto 1 GB of data.  But when i try
to insert using ODBC API's the varchar field takes
only 65484 characters.    But i could insert more characters using INSERT
SQL command.  Even in this case when we fetch the data it reads only 65540
characters. Remaining data is not read from the varchar field.

We have tried in 2 ways

1. table is created without any limit specified for varchar.     create table details (name varchar, data varchar);

2. create table utilntmlscripts (name character varying, data character
varying(10485770));     ERROR:  length for type 'varchar' cannot exceed 10485760     It's not allowing more than 10 MB
ofsize during table creation.
 


Is there anything needs to be configured to make the varchar field to
support upto 1 GB.
Even if it does not support 1 GB, can we store & retrieve atleast 10 MB of
character data
in Varchar field?

Please send the details of how this can be acheived.

Postgres Version 7.4.2
Accessing using UnixODBC driver from C++ application.

thanks,
Vadivel.

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Vadivel Subramaniam wrote:
> 
> Hi,
> 
> We have  a requirement wherein we have to store around 3 MB of data
> in Postgres database.
> 
> We had gone through the postgres website 
> http://www.postgresql.org/docs/7.4/interactive/datatype-character.html#DATATYPE-CHARACTER-SPECIAL-TABLE
> 
> The above link says "varchar" can store upto 1 GB of data. 

I don't think it does, it says the "longest possible character string" 
which covers type "text".
> But when
> i try to insert using ODBC API's the varchar field takes only 65484
> characters.    But i could insert more characters using INSERT SQL
> command.  Even in this case when we fetch the data it reads only
> 65540 characters. Remaining data is not read from the varchar field.

So, your problem is with the ODBC interface rather than actually 
inserting the data.

> We have tried in 2 ways
> 
> 1. table is created without any limit specified for varchar. create
> table details (name varchar, data varchar);
> 
> 2. create table utilntmlscripts (name character varying, data
> character varying(10485770)); ERROR:  length for type 'varchar'
> cannot exceed 10485760 It's not allowing more than 10 MB of size
> during table creation.
> 
> 
> Is there anything needs to be configured to make the varchar field to
>  support upto 1 GB. Even if it does not support 1 GB, can we store &
> retrieve atleast 10 MB of character data in Varchar field?

Check your ODBC settings and try type "text" instead of "varchar". I 
think the problem is with ODBC restrictions rather than anything else. 
You should be able to get type "text" to map to a "Memo" type or 
similar, which should hold more than 64k IIRC.

Failing that, try internal type "bytea" and large-object on the ODBC end.

--  Richard Huxton  Archonet Ltd

Vadivel Subramaniam <vadivel.subramaniam@flextronicssoftware.com> writes:
> 2. create table utilntmlscripts (name character varying, data character
> varying(10485770));
>       ERROR:  length for type 'varchar' cannot exceed 10485760
>       It's not allowing more than 10 MB of size during table creation.

Use type "text", or equivalently varchar with no length specification.

The 1-MB limit on what you can write as a length spec is somewhat
arbitrary, but certainly an enforced length spec larger than that
would be a completely arbitrary number as well ...
        regards, tom lane