From: Phillip Gawlowski <cmdjackryan@...>
Date: 2008-05-26T11:11:25+09:00
Subject: Re: Yup, it's call SQLite! :-)) Re: Is there a One 	TruePostgresinterface? Is Ruby-postgresmaintained?

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Joel VanderWerf wrote:
| John Carter wrote:
|> But unless one or more of those reasons are biting you hard, the
|> simplicity of sqllite is a major win.
|
| On the subject of sqlite (and tangentially ruby), and with all you smart
| folks on the list, a question:
|
| Does anyone know how to keep sqlite from going to disk so much, or is
| that a necessary part of the locking mechanism? Running with strace, the
| write() is immediately followed by fsync(). It keeps my disk very busy
| for what should be cheap insert operations to the end of a table with no
| indexes. Cpu usage is low too (and I'm using SQLite3::Database#prepare
| from the sqlite3 gem, to keep query overhead low).

Two suggestions:
1) Use indexes, as that will improve your performance, and it might just
help with making sure SQLite actually appends directly, instead of
seeking a position first. And the performance improvement even with
small DBs is remarkable: milliseconds instead of seconds..).
2) Are you using transactions? If you don't use transactions, every
insert or update is written to disk immediately, requiring a sync to
disk (we don't want inconsistent data). However, with a transaction,
every operation gets committed to the DB in one go (which is faster,
allows rollbacks in case an operation fails, and should require less
fsync() calls).

- --
Phillip Gawlowski
Twitter: twitter.com/cynicalryan
Blog: http://justarubyist.blogspot.com

Terminate input by end-of-file or marker, not by count.
~            - The Elements of Programming Style (Kernighan & Plaugher)
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