Re: Get the offset of a tuple inside a table

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <hepeimail(at)gmail(dot)com>,<mabewlun(at)gmail(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Get the offset of a tuple inside a table
Date: 2010-09-22 00:47:02
Message-ID: 4C990BB60200002500035AB2@gw.wicourts.gov
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Pei He wrote:

> The offset is the order of a tuple in a Sequential Scan.

That's not a safe assumption. Try starting a sequential scan against
a large table on one connection; then before it finishes, start the
same query on another connection. The second query joins the one
already in progress and then starts over, "wrapping around".

-Kevin

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