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re[2]: [Jdbm-general] Transaction memory size
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From: Kevin D. <ke...@tr...> - 2006-01-16 21:19:52
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<DIV><FONT face=Arial size=2>Eric-</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>No - when transactions
are disabled, they are cached and commited
to disk periodically (behind the scenes,
we manage the size of the uncomitted page
load and write to disk as necessary).
When Tx are off, writes go to only one file
(the db file), instead of writing to the
log, then to the db file.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Because writes
to the log are actually synced to the phyiscal
disk they are usually considerably slower
than non-transactional writes.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Running without
transactions should be several times faster
than running with them (at the risk of corrupting
the database file in the event of a crash,
of course).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>- K</FONT></DIV>
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<TD><FONT face=Arial size=2><FONT color=red>>
<BR>Kevin, <BR> <BR>Thanks for such
a quick response. The main reason I was trying
to avoid committing was because committing
seems to be relatively slow. If I disable
transactions will things be written to disk
immediately? Will this writing be faster
thena commit? <BR><BR>Eric <BR> <BR><BR><BR>From:
Kevin Day <A href="mailto:ke...@tr..."><FONT
color=#0000ff>[mailto:ke...@tr...]</FONT></A>
<BR>Sent: Monday, January 16, 2006 4:02 PM<BR>To:
Rosenberg, Eric<BR>Subject: re: [Jdbm-general]
Transaction memory size <BR> <BR><BR>Eric-
<BR><BR> <BR><BR>This is a limitation
in the current jdbm transaction manager (there
is a group of us working on an alternate
technique that will support arbitrarily large
transactions, but that's a long way off).
<BR><BR> <BR><BR>The recommended approach
at this point is to either: <BR><BR> <BR><BR>A.
Commit your transactions periodically
<BR><BR> <BR><BR>or <BR><BR> <BR><BR>B.
Run with transcations disabled for
large inserts (understand that this will
open you up to potential file corruption,
so you only want to run without transactions
when it is OK to lose the entire database
- i.e. during initial data population). <BR><BR> <BR><BR> <BR><BR>Cheers,
<BR><BR> <BR><BR>- Kevin <BR><BR> <BR><BR> <BR><BR> <BR>>
If I add / update a bunch of objects in JDBM
during a transaction is<BR>everything kept
in memory until I do a commit?<BR><BR>I am
trying to add an arbitrary number of objects
to JDBM and am<BR>wondering if it is safe
to add them all from a single transaction
or if<BR>I need to commit periodically to
ensure that I don't run out of memory.<BR><BR>Thanks,<BR>Eric<BR><BR><BR>-------------------------------------------------------<BR>This
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