-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi
1. Short Export DBMail in a way suitable for incremental backup by standard backup tools, also simplify RDBMBS and DBMail flavours migrarting/upgrading 2. Terminology EEM - everything except emails. This includes user table, mail folders, subsription table, so on. 3. Use RDBMS buitin incremental backup support? Pros: no development is needed Cons: not all RDBMS support this; backup is RDBMS- and DBMail- dependent, so this will not always work with RDBMS and DBMail upgrade, will not help with RDBMS migrating, (requires special setup?) 4. Another Approach We can split the problem into 2 parts: 1. Exporting EEM - here incremental backup is not required 2. Exporting emails - here we need incremental backup 4.1. Export EEM using standard RDBMS export/backup tools Subsequent calls will overwrite EEM. Since the size of EEM is relatively small, should be perfectly O.K. Pros: no special development needed Cons: backup is RDBMS- and DBMail- dependent, so this will not always work with RDBMS and DBMail upgrade, will not help with RDBMS migrating 4.2. Export EEM using special (possibly XML-based) format Subsequent calls will overwrite EEM. Since the size of EEM is relatively small, should be perfectly O.K. Pros: backup is RDBMS-independent, so it makes possible to use it for RDBMS migration, RDBMS upgrade, DBMail upgrade and so on Cons: import-export utilities must be created and maintained 4.3. Export emails to Maildir format Important thing here is not to export the whole Maildir again and again, but only update it, deleting files with old mails and creating files with the new one. Here we can split export into two independent tasks: 1. Exporting new emails 2. Deleting emails which were deleted in DBMail database Task 2 can be done more rare, than task 1. For example, new emails can be injected every day, deleted emails can be cleaned up once a week. Pros: incremental backup will just work Cons: requires huge amount of inodes 4.4. Export emails to Mailbox format Optimization here should be the same as with Maildir - only new mails should be added, deleting of the old emails can be done more rare than injecting new emails. Pros: less inodes comparing to the Maildir Cons: performance sucks, adding one single email to the maibox will trigger backup of the whole Mailbox file - -- Best regards, Sergey Spiridonov -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGeli/J3NEeIx4r3YRAuvmAJ4nyavNZ2oMRpsHSHABrGZKn2ng5QCeMSab sre0SSATYN36gRncW/lAWjM= =/bt3 -----END PGP SIGNATURE----- _______________________________________________ Dbmail-dev mailing list Dbmail-dev@dbmail.org http://twister.fastxs.net/mailman/listinfo/dbmail-dev
