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Re: Bulk Load and Extract from PostgreSQL

From: Sandeep Khandelwal <sandeep_khandelwal27(at)yahoo(dot)com>
To: "Davis, Sean \(NIH/NCI\) \[E\]" <sdavis2(at)mail(dot)nih(dot)gov>, pgsql-interfaces(at)postgresql(dot)org
Subject: Re: Bulk Load and Extract from PostgreSQL
Date: 2006-10-17 12:18:25
Message-ID: 20061017121825.72937.qmail@web33309.mail.mud.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-interfaces
Hi Sean.

The reference that you mentioned is just for Inclusion in the SQL commands directly. But.........

I am trying to load coma seperated data using COPY FROM STDIN command (TEXT mode) and using PQputCopydata API. COPY FROM STDIN command requires user to specify coma seperated text version of all the data.

My question is: If I have binary data(bytea) then I have to convert this data into string (char *) form and pass this data to PostgreSQL using PQputCopydata API. And, I don't have any API in Libpq to convert binary data into string.

Thanks,
Sandeep


----- Original Message ----
From: "Davis, Sean (NIH/NCI) [E]" <sdavis2(at)mail(dot)nih(dot)gov>
To: Sandeep Khandelwal <sandeep_khandelwal27(at)yahoo(dot)com>; pgsql-interfaces(at)postgresql(dot)org
Sent: Tuesday, October 17, 2006 4:13:56 PM
Subject: Re: [INTERFACES] Bulk Load and Extract from PostgreSQL


Sandeep,

Try looking here:

http://www.postgresql.org/docs/8.1/interactive/libpq-exec.html

Under "Escaping Binary Strings for Inclusion in SQL Commands"?  Will that satisfy your needs, or did I miss what you are trying to do?

Sean



-----Original Message-----
From: Sandeep Khandelwal [mailto:sandeep_khandelwal27(at)yahoo(dot)com]
Sent: Tue 10/17/2006 1:36 AM
To: Davis, Sean (NIH/NCI) [E]; pgsql-interfaces(at)postgresql(dot)org
Subject: Re: [INTERFACES] Bulk Load and Extract from PostgreSQL

Hi Sean.

Thanks for the reply.

I have one more question. While extracting data using COPT TO command (in TEXT mode) we have an API, PQunescapeBytea, to convert string representation of binary data(bytea) into binary. Similary we need to convert binary data into it's string representation while loading data into PostgreSQL ,using COPY FROM command in TEXT mode, with PQputCopydata. But there is no API to convert binary data into it's string representation. Could you tell me API or I am misinterpreting something.

Thanks in advance,
Sandeep


----- Original Message ----
From: Sean Davis <sdavis2(at)mail(dot)nih(dot)gov>
To: pgsql-interfaces(at)postgresql(dot)org
Cc: Sandeep Khandelwal <sandeep_khandelwal27(at)yahoo(dot)com>
Sent: Monday, October 16, 2006 4:04:45 PM
Subject: Re: [INTERFACES] Bulk Load and Extract from PostgreSQL


On Monday 16 October 2006 03:07, Sandeep Khandelwal wrote:
> Hi All.
>
> I want to extract and Load data from PostgreSQL using Libpq C API. Please
> let me know which approach will be good to load large number of rows into
> PostgreSQL(Insert or COPY FROM) and, which approach will be good to extract
> large number of rows from PostgreSQL (COPY TO or SELECT). I want to handle
> all the data types supported in the PostgreSQL.

copy is the faster way to go for a single table.  

Sean

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