general questions on Postgresql and deployment on win32 platform
От | Calvin Wood |
---|---|
Тема | general questions on Postgresql and deployment on win32 platform |
Дата | |
Msg-id | cbdadedf04120220281fa78e51@mail.gmail.com обсуждение исходный текст |
Ответы |
Re: general questions on Postgresql and deployment on win32
(Richard Huxton <dev@archonet.com>)
Re: general questions on Postgresql and deployment on (Doug McNaught <doug@mcnaught.org>) |
Список | pgsql-general |
I have gone through the documentation that come with version 8 beta 4 and I have a number of questions. (1) backup/restore I notice that in the documentation, it seems to suggest that an online backup, made via pg_start_backup() and pg_stop_backup() functions would back up all databases running on the server, rather than any specific instance. If that's the case, is it correct to state that WAL is instance specific rather than database specific? Does it also mean that I must back up and restore all the databases (or database cluster in Postgresql Speak) even if I am only interested in 1 database? (2) WAL location I can't seem to find a way to move WAL log to a different location other than data/pg_xlog. On *nix platform, it's a simple matter of creating a symbolic link. But on win32, there is no equivalent. However, even under *nix system, I believe symbolic link can only be created for directories on the same hard drive. This seems less than optimal. Typically, one would place database files on RAID 5 drives (to maximize random access speed) and log files on mirrored drives (to maximize sequential access speed). (3) Trigger Is it correct to state that old and new keywords are only available to PL/pgSQL function (but not a SQL function) and to row level trigger? Is there anyway to refer to old and new rows for statement level trigger? The visibility rule is also quite confusing. Can someone please clarify it in terms of before/after and row/statement level triggers (i.e., 4 possible permutations). (4) Process/thread on win32 platform On win32 platform, a process simply provides environment for a thread to run (whereas a thread is more like a *nix process, win32 has something called fibre that is more lightweight than thread). Typically, it's not recommended to start a new process per connection for DBMS running on win32 lest its performance would suffer. For example, SQL Server actually spawns threads to manage connections rather than processes. Does the Postgresql on win32 platform use process or thread when a connection is made? I notice that the configuration file lets you specify maximum number of connections. If I have a very high number of persistent concurrent users (thus preventing connection pooling from helping much), would performance suffer significantly? Thanks for any responses.
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