Re: [firebird-support] garbage collect
great thanks to make sure I've got this right starting with the same database I can do either a) gbak with gc b) gbak without gc and gfix -sweep and I will have the same final result Extending this further, how can identify which tables contain (or did contain) the garbage. Number of record versions per table in the gstat output. -- With regards, Thomas Steinmaurer http://www.upscene.com/ Professional Tools and Services for Firebird FB TraceManager, IB LogManager, Database Health Check, Tuning etc.
Re: [firebird-support] garbage collect
On Apr 9, 2015, at 11:01 AM, Nick Upson n...@telensa.com [firebird-support] firebird-support@yahoogroups.com wrote: to make sure I've got this right Not quite. starting with the same database I can do either a) gbak with gc Won't advance the oldest active b) gbak without gc and gfix -sweep Will move the oldest active and will get a few more records than a) and I will have the same final result Best is gback with garbage collect plus sweep: moves the oldest actives, gets the most old versions, shouldn't take much longer since the sweep doesn't do much. Extending this further, how can identify which tables contain (or did contain) the garbage. gstat shows the number of versions present before you start. good luck, Ann
Re: [firebird-support] garbage collect
great thanks to make sure I've got this right starting with the same database I can do either a) gbak with gc b) gbak without gc and gfix -sweep and I will have the same final result Extending this further, how can identify which tables contain (or did contain) the garbage. As well as handling it better I'm trying to see if we can cause less of it Nick Upson, Telensa Ltd, Senior Operations Network Engineer direct +44 (0) 1799 533252, support hotline +44 (0) 1799 399200 On 5 April 2015 at 18:07, Ann Harrison aharri...@ibphoenix.com [firebird-support] firebird-support@yahoogroups.com wrote: On Apr 5, 2015, at 11:23 AM, Nick Upson n...@telensa.com [firebird-support] firebird-support@yahoogroups.com wrote: is there any effective difference between doing gbak with gc and gbak without gc and then gfix -sweep The only differences (that I can think of) are caused by concurrent actions. If you garbage collect during backup, the sweep can remove new garbage created while the backup ran. Imagine that garbage collection takes enough time for fine thousand transactions to complete and each of those transactions makes three record versions obsolete. Neither gbak nor sweep can remove record versions made obsolete by the completion of a concurrent transaction. So if you backup without garbage collection, your backup is quicker, sweep starts sooner and takes longer so those 15,000 old record versions continue moldering in your database. If you backup with garbage collection and then sweep, the backup is slower, but the sweep starts later and can remove those unlovable record versions. Sort of a wash, rinse, repeat thing - if that phrase means anything to those who aren't elderly Americans. Cheers, Ann From sunny Sint Maarten.
[firebird-support] garbage collect
Hi I'd like to do my backup without gc and then do the gc separately - is there any effective difference between doing gbak with gc and gbak without gc and then gfix -sweep Nick Upson, Telensa Ltd, Senior Operations Network Engineer direct +44 (0) 1799 533252, support hotline +44 (0) 1799 399200
Re: [firebird-support] garbage collect
On Apr 5, 2015, at 11:23 AM, Nick Upson n...@telensa.com [firebird-support] firebird-support@yahoogroups.com wrote: is there any effective difference between doing gbak with gc and gbak without gc and then gfix -sweep The only differences (that I can think of) are caused by concurrent actions. If you garbage collect during backup, the sweep can remove new garbage created while the backup ran. Imagine that garbage collection takes enough time for fine thousand transactions to complete and each of those transactions makes three record versions obsolete. Neither gbak nor sweep can remove record versions made obsolete by the completion of a concurrent transaction. So if you backup without garbage collection, your backup is quicker, sweep starts sooner and takes longer so those 15,000 old record versions continue moldering in your database. If you backup with garbage collection and then sweep, the backup is slower, but the sweep starts later and can remove those unlovable record versions. Sort of a wash, rinse, repeat thing - if that phrase means anything to those who aren't elderly Americans. Cheers, Ann From sunny Sint Maarten.
