Date: Tue, 13 May 2008 15:44:06 +0400 From: Anthony Pankov <ap00@mail.ru> To: freebsd-hackers@freebsd.org Subject: Re[2]: BDB corrupt Message-ID: <2117635718.20080513154406@mail.ru> In-Reply-To: <20080512152430.3720683e@mbook.local> References: <op.uavxx8ip2n4ijf@duckjen.nextgentel.no> <9FC19AC2-DAD8-418C-8B9C-F129DEC58CEF@gmail.com> <15336578.20080512123806@mail.ru> <200805121153.00809.jonathan%2Bfreebsd-hackers@hst.org.za> <1663320218.20080512223531@mail.ru> <20080512152430.3720683e@mbook.local>
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Monday, Mike Meyer May 12, 2008, 11:24:30 PM, you wrote: MM> On Mon, 12 May 2008 22:35:31 +0400 Anthony Pankov <ap00@mail.ru> wrote: >> Because BDB: >> 1. do not need additional installation >> 2. is part of base system which mean it is mature, reliable and stable MM> BDB in the base system is mature, reliable and stable *for what it's MM> used for in the base system.* So long as your requirements are covered MM> by that usage, you'll be ok. MM> The uses I know of for BDB in the base system all consist of databases MM> of relatively small items that are changed infrequently, and usually MM> with a locking mechanism. From what you've said, this doesn't describe MM> your requirements. MM> More importantly, from what other people are saying, your requirements MM> are ones for which it's known that BDB is *not* reliable, or otherwise MM> unsuitable. In particular, an effort is underway to allow parallel MM> ports builds, which implies concurrent access to the database, which MM> is a known source of problems for BDB. MM> <mike My requirements is 1. there is no need for SQL 2. processes are sharing db file in concurrent mode 3. reading/writing = 60%/40% With BDB clause 1 - satisfied clause 3 - satisfied (databases of relatively small items that are changed infrequently). Is there a problem with concurrent access? And, most important, is this the ONLY problem? (I still don't understand because of blurred mention of "data corruption".) If concurrency is the only problem then: 1. Ņan data corruption be avoided? Or this is impossible? 2. How? If all BDB readers would use O_SHLOCK and all writers O_EXLOCK is it guarantee for data integrity? -- Best regards, Anthony mailto:ap00@mail.ru
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