Re: Should we improve documentation on isolation levels?

I am not sure if i am posting in the right place - correct me if I am wrong.
The following is not precise:

13.2.1. Read Committed Isolation Level

"Also note that two successive SELECT commands can see different data, even
though they are within a single transaction, if other transactions commit
changes during execution of the first SELECT."

I think it should be re-worded as follows

"Also note that two successive SELECT commands can see different data, even
though they are within a single transaction, if other transactions commit
after the first SELECT starts, and before the second SELECT starts."

The reason: there could be other DML running between these two SELECTs.

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AK <alkuzo(at)gmail(dot)com> wrote:

> The following is not precise:
>
> 13.2.1. Read Committed Isolation Level
>
> "Also note that two successive SELECT commands can see different data, even
> though they are within a single transaction, if other transactions commit
> changes during execution of the first SELECT."
>
> I think it should be re-worded as follows
>
> "Also note that two successive SELECT commands can see different data, even
> though they are within a single transaction, if other transactions commit
> after the first SELECT starts, and before the second SELECT starts."
>
> The reason: there could be other DML running between these two SELECTs.

That's a fair point.  I'll commit something to the master branch.
I don't think this rises to the level of a documentation bug that
needs to be back-patched.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

I concur - the documentation is not incorrect, it is just incomplete.

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AK <alkuzo(at)gmail(dot)com> wrote:

> the documentation is not incorrect, it is just incomplete.

Yeah, that's exactly how I saw it.  :-)

Docs changed on master only.  Thanks for the report!

--

Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company