Re: Does Postgres support bookmarks (tuples ids)?

Dann,
it is a very good suggestion! How does OLEDB implement the bookmarks? Is
there a specific Postgres feature that is used for the bookmarks?

Thank you!
Konstantin

On Tue, Nov 30, 2010 at 11:13 PM, Dann Corbit <DCorbit(at)connx(dot)com> wrote:

> Is your application by chance using OLEDB?
>
> If that is the case, then just get a PostgreSQL OLEDB provider that
> supports bookmarks.
>
>
>
> *From:* pgsql-general-owner(at)postgresql(dot)org [mailto:
> pgsql-general-owner(at)postgresql(dot)org] *On Behalf Of *Konstantin Izmailov
> *Sent:* Tuesday, November 30, 2010 9:50 PM
> *To:* pgsql-general(at)postgresql(dot)org
> *Subject:* [GENERAL] Does Postgres support bookmarks (tuples ids)?
>
>
>
> Dear experts,
>
> I've noticed that commercial databases (e.g. SQLServer) and some open
> source databases (e.g. Cubrid) support so called "bookmarks".
> As far as I understood, a bookmark allows quickly jump to a row for
> retrieval or modification.
>
> Here is scenario that I'm trying to deal with:
> A BI/ETL application is querying the Postgres database. The queries return
> lots of rows (36 mil), each is about 1KB or larger.
> So I'm using DECLARE CURSOR/FETCH to read the rows into a buffer (size is
> 10000 rows, and I'm freeing memory for oldest rows).
> The application may alter or re-read some previously read rows by the row
> index.
> Problem is: if a row is not in the buffer (freed) the application cannot
> resolve row index into row itself.
> I considered using a unique key to located the row, but unfortunately some
> queries do no allows determining the most unique key.
>
> I'm thinking, is it possible to retrieve/alter row by its index after a
> Postgres Cursor have read the row?
>
> The application allows a customer to define DB Schema as well as the
> queries, so my code does not have a prior knowledge about DB and queries.
> It is supposed to provide a certain API with functions based on row
> indexes. The API was initially designed for SQLServer, so the goal is to
> migrate the application from SQLServer to Postgres.
>
> Would you recommend a solution?
>
> Thank you
> Konstantin
>