What makes you think you need database connection pooling? Apache::DBI gives persistent connections, which solves the speed problem. It's easy to use, and whatever caveats you've heard are probably exaggerated. Unless some of your mod_perl processes are handling requests that don't involve a database at all, they should hold onto their connections.
Doing actual sharing of database handles is hard, since it involves passing sockets and file handles around between processes safely. That's why it hasn't been done. | [reply] |
I agree that it's often unnecessary to pool database connections, especially if the heavyweight Web servers are configured to use a lightweight front-end server as recommended in the mod_perl guide. I also agree that it's difficult to do. DBD::Proxy looks like an interesting attempt to deal with this, although its documentation mentions that its connect_cached method, which pools connections using an intermediary process, is new and still experimental. It might be worth a look, though.
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[d/l] |
It's not worth a look. It's very slow.
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Whether connection pooling can be done "easily" depends on how the underlying database client library handles sockets. AFAIK Oracle OCI doesn't support sharing connections between different clients, meaning that you'd actually have to write your own server daemon that sits between your web server and Oracle. This is seriously non-trivial to get right.
At a previous job we wrote such a beast - actually at the time we used FreeBSD for the front-end, and there were no Sybase libraries available for that platform. So we designed a simple communication protocol, with a server on the front-end listening on a Unix domain socket and then communicating with a multi-threaded server on the middle tier that itself talked to Sybase. It worked reasonably well, but there were always problems, and maintaining the two multi-threaded apps was a pain.
As perrin says - just use Apache::DBI, and maybe use a lightweight http proxy front-end to limit the number of processes that need to have a database connection.
Michael
P.S. - now if you were using Sybase instead you could use Apache::Sybase::ConPool
:-)
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You might want to look at ResourcePool, which does this outside of a web framework and for different types of datasources.
Chris
M-x auto-bs-mode
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That looks like it's only for a single process though. Not much use for pooling anything in a multi-process server like Apache/mod_perl.
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You should look at
SQL Relay. From it's description:
"SQL Relay is a persistent database connection pooling, proxying and load balancing system for Unix and Linux supporting ODBC, Oracle, MySQL, mSQL, PostgreSQL, Sybase, MS SQL Server, IBM DB2, Interbase, Lago and SQLite with C, C++, Perl, Perl-DBD, Python, Python-DB, Zope, PHP, Ruby and Java APIs, command line clients, a GUI configuration tool and extensive documentation. The APIs support advanced database operations such as bind variables, multi-row fetches, client side result set caching and suspended transactions. It is ideal for speeding up database-driven web-based applications, accessing databases from unsupported platforms, migrating between databases, distributing access to replicated databases and throttling database access.
"
I have not used it, but it does have a great deal of documentation and an apparently active email list. | [reply] |