On Thu, Dec 29, 2011 at 11:33 AM, Aleksej Trofimov <aleksej.trofimov@xxxxxxxxxx> wrote: > Postgres Streaming replication is WAL based replication, so using this type > of replication you will have absolutely identical database servers, what is > best choice for HA and scaling reads. Also this choice is not practically > affecting performance, because it is not adding any latency to database > layer. Let me chime in, because I'm in a similar situation. I'm preparing a POC WAL-replicated environment, and testing up until now has been inconclusive since we lack the kind of hardware in our test environment. I know I should require it, testing on similar hardware is the only way to get reliable results, but getting the budget approved would take way too long, and right now we're in a hurry to scale reads. So getting the hardware is not an option, my option is asking those who have the experience :-) I gather WAL replication introduces only a few possible bottlenecks. First, network bandwidth between master and slaves, and my app does write a lot - our monitoring tools show, today, an average of 1MB/s writes on the WAL array, with peaks exceeding 8MB/s, which can easily saturate our lowly 100Mb/s links. No worries, we can upgrade to 1Gb/s links. Second, is that WAL activity on streaming replication or WAL shipping is documented to contain more data than on non-replicated setups. What is not clear is how much more data. This not only affects our network bandwidth estimations, but also I/O load on the master server, slowing writes (and some reads that cannot happen on the slave). So, my question is, in your experience, how much of an increase in WAL activity can be expected? -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
