Обсуждение: Hot Backup
Hello to all the Doers of Postgres!!! Last time I went through forums, people spoke highly about 7.3 and its capability to do hot backups. My problem is if thedatabase goes down and I lose my main data store, then I will lose all transactions back to the time I did the pg_dump. Other databases (i e Oracle) solves this by retaining their archive logs in some physically separate storage. So, when youlose your data, you can restore the data from back-up, and then apply your archive log, and avoid losing any committedtransactions. Postgresql has been lacking this all along. I've installed postgres 7.3b2 and still don't see any archive's flushed to anyother place. Please let me know how is hot backup procedure implemented in current 7.3 beta(2) release. Thanks.
Hi Sandeep. What you were calling Hot Backup is really called Point in Time Recovery (PITR). Hot Backup means making a complete backup of the database while it is running, something Postgresql has supported for a very long time. On Mon, 7 Oct 2002, Sandeep Chadha wrote: > Hello to all the Doers of Postgres!!! > > Last time I went through forums, people spoke highly about 7.3 and its > capability to do hot backups. My problem is if the database goes down > and I lose my main data store, then I will lose all transactions back > to the time I did the pg_dump. Let's make it clear that this kind of failure is EXTREMELY rare on real database servers since they almost ALL run their data sets on RAID arrays. While it is possible to lost >1 drive at the same time and all your database, it is probably more likely to have a bad memory chip corrupt your data silently, or a bad query delete data it shouldn't. That said, there IS work ongoing to provide this facility for Postgresql, but I would much rather have work done on making large complex queries run faster, or fix the little issues with foreign keys cause deadlocks. > Other databases (i e Oracle) solves this by retaining their archive > logs in some physically separate storage. So, when you lose your data, > you can restore the data from back-up, and then apply your archive log, > and avoid losing any committed transactions. > > > Postgresql has been lacking this all along. I've installed postgres > 7.3b2 and still don't see any archive's flushed to any other place. > Please let me know how is hot backup procedure implemented in current > 7.3 beta(2) release. Again, you'll get better response to your questions if you call it "point in time recovery" or pitr. Hot backup is the wrong word, and something Postgresql DOES have. It also supports WALs, which stands for Write ahead logs. These files store what the database is about to do before it does it. Should the database crash with transactions pending, the server will come back up and process the pending transactions that are in the WAL files, ensuring the integrity of your database. Point in Time recovery is very nice, but it's the last step in many to ensure a stable, coherent database, and will probably be in 7.4 or somewhere around there. If you're running in a RAID array, then the loss of your datastore should be a very remote possibility.
Hi All,
I have a question related to postgres.I have an application which is transferring data from MSSQL to Postgres at some regular interval.
I had around 20,000 data in MSSQL which should be transferred to postgres.
After transferring around 12000 data I got a error message
ERROR: deadlock detected
And after that data transfer has stopped.
How to avoid this error and what is the reason for this error.
--
Best Regards
- Savita
----------------------------------------------------
Hewlett Packard (India)
+91 80 2051288 (Phone)
847 1288 (HP Telnet)
----------------------------------------------------
On Fri, 22 Nov 2002, Savita wrote: > Hi All, > > I have a question related to postgres.I have an application which is > transferring data from MSSQL to Postgres at some regular interval. > > I had around 20,000 data in MSSQL which should be transferred to postgres. > After transferring around 12000 data I got a error message > ERROR: deadlock detected > And after that data transfer has stopped. > > How to avoid this error and what is the reason for this error. Most likely cause would be a concurrent transaction doing something that caused a foreign key to get into a dead lock situation (the current implementation grabs overly strong locks). In any case, we'll need more information about what else was going on probably.
Thanks Stephan, I wold like to know where to get LOCK manual/reference. And what is ther error number it will return when this error will come.Is there any work around this.HOw do I avoid this situation. -- Best Regards - Savita ---------------------------------------------------- Hewlett Packard (India) +91 80 2051288 (Phone) 847 1288 (HP Telnet) ---------------------------------------------------- Stephan Szabo wrote: > On Fri, 22 Nov 2002, Savita wrote: > > > Hi All, > > > > I have a question related to postgres.I have an application which is > > transferring data from MSSQL to Postgres at some regular interval. > > > > I had around 20,000 data in MSSQL which should be transferred to postgres. > > After transferring around 12000 data I got a error message > > ERROR: deadlock detected > > And after that data transfer has stopped. > > > > How to avoid this error and what is the reason for this error. > > Most likely cause would be a concurrent transaction doing something that > caused a foreign key to get into a dead lock situation (the current > implementation grabs overly strong locks). In any case, we'll need more > information about what else was going on probably.
On Fri, 22 Nov 2002, Savita wrote: > I wold like to know where to get LOCK manual/reference. Well, there's the entry for the LOCK command, but I don't think that's what you want, what exactly are you looking for? > And what is ther error number it will return when this error will come.Is there > any work around this.HOw do I avoid this situation. I don't know of an error number, but the string will will have that deadlock detected in it. :) As for a workaround, since we don't know what's causing it, we can't really give you a workaround. What's the schema of the table you're transferring to and what else was going on in the server at the time you got the deadlock? I'd guess it was a foreign key, but that only applies if you've got foreign keys, for example.
Hello, You try load data first and then referential constraints regards Haris Peco On Friday 22 November 2002 07:10 am, Savita wrote: > Thanks Stephan, > > I wold like to know where to get LOCK manual/reference. > > And what is ther error number it will return when this error will come.Is > there any work around this.HOw do I avoid this situation. > > -- > Best Regards > - Savita > ---------------------------------------------------- > Hewlett Packard (India) > +91 80 2051288 (Phone) > 847 1288 (HP Telnet) > ---------------------------------------------------- > > Stephan Szabo wrote: > > On Fri, 22 Nov 2002, Savita wrote: > > > Hi All, > > > > > > I have a question related to postgres.I have an application which is > > > transferring data from MSSQL to Postgres at some regular interval. > > > > > > I had around 20,000 data in MSSQL which should be transferred to > > > postgres. After transferring around 12000 data I got a error message > > > ERROR: deadlock detected > > > And after that data transfer has stopped. > > > > > > How to avoid this error and what is the reason for this error. > > > > Most likely cause would be a concurrent transaction doing something that > > caused a foreign key to get into a dead lock situation (the current > > implementation grabs overly strong locks). In any case, we'll need more > > information about what else was going on probably. > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/users-lounge/docs/faq.html
I recommend reading Tom Lane's talk "Concurrency Issues" at OSCON2002.
This will answer all questions and some more.
Best regards,
Hans
Savita wrote:
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>Hi All,
>
>I have a question related to postgres.I have an application which is transferring data from MSSQL to Postgres at some
regularinterval.
>
>I had around 20,000 data in MSSQL which should be transferred to postgres.
>After transferring around 12000 data I got a error message
>ERROR: deadlock detected
>And after that data transfer has stopped.
>
>How to avoid this error and what is the reason for this error.
>--
>Best Regards
>- Savita
>----------------------------------------------------
>Hewlett Packard (India)
>+91 80 2051288 (Phone)
>847 1288 (HP Telnet)
>----------------------------------------------------
>
>
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>Hi All,
><p>I have a question related to postgres.I have an application which is
>transferring data from MSSQL to Postgres at some regular interval.
><p>I had around 20,000 data in MSSQL which should be transferred to postgres.
><br>After transferring around 12000 data I got a error message
><br><b><font color="#3333FF">ERROR: deadlock detected</font></b>
><br><font color="#000000">And after that data transfer has stopped.</font><font color="#000000"></font>
><p><font color="#000000">How to avoid this error and what is the reason
>for this error.</font>
><br>--
><br>Best Regards
><br>- Savita
><br>----------------------------------------------------
><br>Hewlett Packard (India)
><br>+91 80 2051288 (Phone)
><br>847 1288 (HP Telnet)
><br>----------------------------------------------------
><br> </html>
>
>--------------880B7BB5722DEBFDA92AF2C3--
>
>
>
--
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I haven't seen this before, and I can't find it on techdocs. Can you post a link to it? -tfo In article <3DDDE7D0.5040803@cybertec.at>, Hans-Jurgen Schonig <hs@cybertec.at> wrote: > I recommend reading Tom Lane's talk "Concurrency Issues" at OSCON2002. > This will answer all questions and some more. > > Best regards, > > Hans
"Thomas O'Connell" <tfo@monsterlabs.com> writes: > Hans-Jurgen Schonig <hs@cybertec.at> wrote: >> I recommend reading Tom Lane's talk "Concurrency Issues" at OSCON2002. > I haven't seen this before, and I can't find it on techdocs. Can you > post a link to it? You can find a PDF at O'Reilly's conferences archive, http://conferences.oreillynet.com/cs/os2002/view/e_sess/2681 I recall asking Vince to put a copy on the Postgres website, but I don't think he ever got around to it. regards, tom lane