Re: [PERFORM] Replication: Slony-I vs. Mammoth Replicator vs. ?
One more point for your list: Choose Slony if Replicator doesn't support your platform. :-) -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Vivek Khera, Ph.D.Khera Communications, Inc. Internet: [EMAIL PROTECTED] Rockville, MD +1-301-869-4449 x806 AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/ ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] Replication: Slony-I vs. Mammoth Replicator vs. ?
Once again, Joshua, would you please explain what you mean with batch and live replication system? Slony does group multiple master transactions into one replication transaction to improve performance (fewer commits on the slaves). The interval of these groups is configurable and for high volume DBs it is recommended to use about one second, which means that all commits that fall into an interval of one second are replicated in one transaction on the slave. On normal running systems this results in a replication lag of 600 to 800 milliseconds in average. On overloaded systems the asynchronous nature of course allows the slaves to fall behind. Your description above is what I considered batch... you are taking a batch of transactions and replicating them versus each transaction. I am not saying it is bad in any way. I am just saying it is different that replicator. What is a usual average replication lag of Mammoth Replicator? Obviously it depends on the system, the network connectivity between the systems etc... In our test systems it takes less than 100 ms to replicate the data. Again it depends on the size of the transaction (the data being moved). What happens to the other existing slaves when you promote by hand? This is something that Slony has over replicator. Currently the new master will force a full dump to the slaves. Of course this is already on the road map, thanks to Slony :) and should be resolved by months end. The Slony documentation is an issue at the moment and the administrative tools around it are immature. The replication engine itself exceeds my own expectations and performs very robust. I have never suggested otherwise. My only comment about maturity is that their are actually many companies using replicator in production. We have already dealt with the 1.0 blues as they say. I hope you understand that I, in no way have ever suggested (purposely) anything negative about Slony. Only that I believe they serve different technical solutions. Sincerely, Joshua D. Drake Jan -- Command Prompt, Inc., home of Mammoth PostgreSQL - S/ODBC and S/JDBC Postgresql support, programming shared hosting and dedicated hosting. +1-503-667-4564 - [EMAIL PROTECTED] - http://www.commandprompt.com PostgreSQL Replicator -- production quality replication for PostgreSQL ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] Replication: Slony-I vs. Mammoth Replicator vs. ?
Centuries ago, Nostradamus foresaw when [EMAIL PROTECTED] (Joshua D. Drake) would write: I hope you understand that I, in no way have ever suggested (purposely) anything negative about Slony. Only that I believe they serve different technical solutions. Stipulating that I may have some bias ;-), I still don't find it at all clear what the different situations are shaped like that lead to Mammoth being forcibly preferable to Slony-I. (Note that I have a pretty decent understanding about how ERS and Slony work, so I'm not too frightened of technicalities... I set up instances of both on Thursday, so I'm pretty up to speed :-).) Win32 support may be true at the moment, although I have to discount that as we only just got the start of a beta release of native Win32 support for PostgreSQL proper. For that very reason, I had to point my youngest brother who needed something better than Access to Firebird last Saturday; I played with my niece while he was doing the install. And there is little reason to think that Slony-I won't be portable to Win32 given a little interest and effort, particularly once work to make it play well with pgxs gets done. -- (format nil [EMAIL PROTECTED] cbbrowne ntlug.org) http://www3.sympatico.ca/cbbrowne/multiplexor.html At Microsoft, it doesn't matter which file you're compiling, only which flags you #define. -- Colin Plumb ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
Re: [PERFORM] Replication: Slony-I vs. Mammoth Replicator vs. ?
Christopher Browne wrote:
Centuries ago, Nostradamus foresaw when [EMAIL PROTECTED] ("Joshua D. Drake") would write:
I hope you understand that I, in no way have ever suggested
(purposely) anything negative about Slony. Only that I believe they
serve different technical solutions.
Stipulating that I may have some bias ;-), I still don't find it at
all clear what the different situations are "shaped like" that lead to
Mammoth being forcibly preferable to Slony-I.
I would choose replicator if:
1. You want ease of setup
2. You want your each transaction to be replicated at time of commit
3. Your database is already laden with triggers
4. You are pushing a very high transactional load*
* Caveat I have no idea how well Slony performs on a system that does
say 200,000 transactions
an hours that are heavily geared toward updates. Replicator performs
very well in this scenario.
5. Replicators administrative tools are more mature than Slony (for
example you know exactly what state your slaves are in with Replicator).
I would choose Slony if:
1. The fact that it is Open Source matters to you
2. The auto promotion of slaves is important*
*This will be fixed in a couple of weeks with Replicator
To be fair, in the real world ---
It doesn't make a bit of difference which one you choose it really
comes down to this:
Replicator is dumb simple to setup. Any halfway talented person can
setup replicator
in 30 minutes with a single master / slave configuration.
Slony is Open Source and thus a little easier on the pocket book
initially.
Command Prompt, will support either one -- so the Replicator is
commercially supported
argument is a little weak here.
Sincerely,
Joshua D. Drake
Sincerely,
Joshua D. Drake
(Note that I have a pretty decent understanding about how ERS and
Slony work, so I'm not too frightened of technicalities... I set up
instances of both on Thursday, so I'm pretty up to speed :-).)
Win32 support may be true at the moment, although I have to discount
that as we only just got the start of a beta release of native Win32
support for PostgreSQL proper. For that very reason, I had to point
my youngest brother who needed "something better than Access" to
Firebird last Saturday; I played with my niece while he was doing the
install. And there is little reason to think that Slony-I won't be
portable to Win32 given a little interest and effort, particularly
once work to make it play well with "pgxs" gets done.
--
Command Prompt, Inc., home of Mammoth PostgreSQL - S/ODBC and S/JDBC
Postgresql support, programming shared hosting and dedicated hosting.
+1-503-667-4564 - [EMAIL PROTECTED] - http://www.commandprompt.com
PostgreSQL Replicator -- production quality replication for PostgreSQL
Re: [PERFORM] Replication: Slony-I vs. Mammoth Replicator vs. ?
Chris Cheston wrote: HI all, I'm trying to implement a highly-scalable, high-performance, real-time database replication system to back-up my Postgres database as data gets written. So far, Mammoth Replicator is looking pretty good but it costs $1000+ . Yes but it includes 30 days of support and 12 months of upgrades/updates :) Has anyone tried Slony-I and other replication systems? Slony-I is pretty new so I'm a little unsure if it's ready for a prime-time commercial system yet. It really depends on your needs. They are both good systems. Slony-I is a bit more of a beast to get up and running, and it is a batch replication system that uses triggers. Once it is up and running it works well though. Mammoth Replicator is easy to setup and is integrated into PostgreSQL. However replicator is 1000+ and doesn't support promoting of slaves automatically (you can do it by hand) like Slony does. Replicator is also live replication. Sincerely, Joshua D. Drake So... wanted to put this out to the experts. Has anyone got any recommendations or had experiences with real-time database replication solutions that don't rely on RAID? The reason why I don't want to rely on a hardware solution is because we are renting dedicated servers and we don't have access to the boxes, only to software that gets installed on the boxes. Thanks, Chris ---(end of broadcast)--- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match -- Command Prompt, Inc., home of Mammoth PostgreSQL - S/ODBC and S/JDBC Postgresql support, programming shared hosting and dedicated hosting. +1-503-667-4564 - [EMAIL PROTECTED] - http://www.commandprompt.com Mammoth PostgreSQL Replicator. Integrated Replication for PostgreSQL begin:vcard fn:Joshua D. Drake n:Drake;Joshua D. org:Command Prompt, Inc. adr:;;PO Box 215;Cascade Locks;Oregon;97014;USA email;internet:[EMAIL PROTECTED] title:Consultant tel;work:503-667-4564 tel;fax:503-210-0034 note:Command Prompt, Inc. is the largest and oldest US based commercial PostgreSQL support provider. We provide the only commercially viable integrated PostgreSQL replication solution, but also custom programming, and support. We authored the book Practical PostgreSQL, the procedural language plPHP, and adding trigger capability to plPerl. x-mozilla-html:FALSE url:http://www.commandprompt.com/ version:2.1 end:vcard ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
