Artifact 48d946181712dc8f97cff5b6a039d06755a75258:
File www/selfcheck.html part of check-in [469002ccdf] - Added navbar to all pages, linking back to the index. Fixed typo in the index page. by aku on 2007-09-12 04:19:59. Also file www/selfcheck.html part of check-in [bbcb6326c9] - Pulled in the navbar and timeline changes. by aku on 2007-09-17 00:58:51.
0000: 3c 68 74 6d 6c 3e 0a 3c 68 65 61 64 3e 0a 3c 74 <html>.<head>.<t 0010: 69 74 6c 65 3e 46 6f 73 73 69 6c 20 52 65 70 6f itle>Fossil Repo 0020: 73 69 74 6f 72 79 20 49 6e 74 65 67 72 69 74 79 sitory Integrity 0030: 20 53 65 6c 66 2d 43 68 65 63 6b 73 3c 2f 74 69 Self-Checks</ti 0040: 74 6c 65 3e 0a 3c 2f 68 65 61 64 3e 0a 3c 62 6f tle>.</head>.<bo 0050: 64 79 20 62 67 63 6f 6c 6f 72 3d 22 77 68 69 74 dy bgcolor="whit 0060: 65 22 3e 0a 3c 70 3e 5b 20 3c 61 20 68 72 65 66 e">.<p>[ <a href 0070: 3d 22 69 6e 64 65 78 2e 68 74 6d 6c 22 3e 49 6e ="index.html">In 0080: 64 65 78 3c 2f 61 3e 20 5d 3c 2f 70 3e 0a 3c 68 dex</a> ]</p>.<h 0090: 72 3e 0a 3c 68 31 20 61 6c 69 67 6e 3d 22 63 65 r>.<h1 align="ce 00a0: 6e 74 65 72 22 3e 0a 46 6f 73 73 69 6c 20 52 65 nter">.Fossil Re 00b0: 70 6f 73 69 74 6f 72 79 20 49 6e 74 65 67 72 69 pository Integri 00c0: 74 79 20 53 65 6c 66 2d 43 68 65 63 6b 73 0a 3c ty Self-Checks.< 00d0: 2f 68 31 3e 0a 0a 3c 70 3e 0a 45 76 65 6e 20 74 /h1>..<p>.Even t 00e0: 68 6f 75 67 68 20 66 6f 73 73 69 6c 20 69 73 20 hough fossil is 00f0: 61 20 72 65 6c 61 74 69 76 65 6c 79 20 6e 65 77 a relatively new 0100: 20 70 72 6f 6a 65 63 74 20 61 6e 64 20 73 74 69 project and sti 0110: 6c 6c 20 63 6f 6e 74 61 69 6e 73 0a 6d 61 6e 79 ll contains.many 0120: 20 62 75 67 73 2c 20 69 74 20 69 73 20 64 65 73 bugs, it is des 0130: 69 67 6e 65 64 20 77 69 74 68 20 66 65 61 74 75 igned with featu 0140: 72 65 73 20 74 6f 20 67 69 76 65 20 69 74 20 61 res to give it a 0150: 20 68 69 67 68 20 6c 65 76 65 6c 0a 6f 66 20 69 high level.of i 0160: 6e 74 65 67 72 69 74 79 20 73 6f 20 74 68 61 74 ntegrity so that 0170: 20 79 6f 75 20 63 61 6e 20 68 61 76 65 20 63 6f you can have co 0180: 6e 66 69 64 65 6e 63 65 20 74 68 61 74 20 79 6f nfidence that yo 0190: 75 20 77 69 6c 6c 20 6e 6f 74 0a 6c 6f 73 65 20 u will not.lose 01a0: 79 6f 75 72 20 66 69 6c 65 73 2e 20 20 54 68 69 your files. Thi 01b0: 73 20 6e 6f 74 65 20 64 65 73 63 72 69 62 65 73 s note describes 01c0: 20 74 68 65 20 64 65 66 65 6e 73 69 76 65 20 6d the defensive m 01d0: 65 61 73 75 72 65 73 20 74 68 61 74 0a 66 6f 73 easures that.fos 01e0: 73 69 6c 20 75 73 65 73 20 74 6f 20 68 65 6c 70 sil uses to help 01f0: 20 70 72 65 76 65 6e 74 20 66 69 6c 65 20 6c 6f prevent file lo 0200: 73 73 20 64 75 65 20 74 6f 20 62 75 67 73 2e 0a ss due to bugs.. 0210: 3c 2f 70 3e 0a 0a 3c 68 32 3e 41 74 6f 6d 69 63 </p>..<h2>Atomic 0220: 20 43 68 65 63 6b 2d 69 6e 73 20 57 69 74 68 20 Check-ins With 0230: 52 6f 6c 6c 62 61 63 6b 3c 2f 68 32 3e 0a 0a 3c Rollback</h2>..< 0240: 70 3e 0a 54 68 65 20 66 6f 73 73 69 6c 20 72 65 p>.The fossil re 0250: 70 6f 73 69 74 6f 72 79 20 69 73 20 61 6e 0a 3c pository is an.< 0260: 61 20 68 72 65 66 3d 22 68 74 74 70 3a 2f 2f 77 a href="http://w 0270: 77 77 2e 73 71 6c 69 74 65 2e 6f 72 67 2f 22 3e ww.sqlite.org/"> 0280: 53 51 4c 69 74 65 20 76 65 72 73 69 6f 6e 20 33 SQLite version 3 0290: 3c 2f 61 3e 20 64 61 74 61 62 61 73 65 20 66 69 </a> database fi 02a0: 6c 65 2e 20 20 0a 53 51 4c 69 74 65 20 69 73 20 le. .SQLite is 02b0: 76 65 72 79 20 6d 61 74 75 72 65 20 61 6e 64 20 very mature and 02c0: 73 74 61 62 6c 65 20 61 6e 64 20 68 61 73 20 62 stable and has b 02d0: 65 65 6e 20 69 6e 20 77 69 64 65 2d 73 70 72 65 een in wide-spre 02e0: 61 64 20 75 73 65 20 66 6f 72 20 6d 61 6e 79 0a ad use for many. 02f0: 79 65 61 72 73 2c 20 73 6f 20 77 65 20 68 61 76 years, so we hav 0300: 65 20 6c 69 74 74 6c 65 20 77 6f 72 72 69 65 73 e little worries 0310: 20 74 68 61 74 20 69 74 20 6d 69 67 68 74 20 63 that it might c 0320: 61 75 73 65 20 72 65 70 6f 73 69 74 6f 72 79 0a ause repository. 0330: 63 6f 72 72 75 70 74 69 6f 6e 2e 20 20 53 51 4c corruption. 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If some kin 03c0: 64 20 6f 66 20 63 72 61 73 68 0a 64 6f 65 73 20 d of crash.does 03d0: 6f 63 63 75 72 20 69 6e 20 74 68 65 20 6d 69 64 occur in the mid 03e0: 64 6c 65 20 6f 66 20 61 20 63 68 61 6e 67 65 2c dle of a change, 03f0: 20 74 68 65 6e 20 61 6c 6c 20 74 68 65 20 63 68 then all the ch 0400: 61 6e 67 65 73 20 61 72 65 20 72 6f 6c 6c 65 64 anges are rolled 0410: 0a 62 61 63 6b 20 74 68 65 20 6e 65 78 74 20 74 .back the next t 0420: 69 6d 65 20 74 68 61 74 20 74 68 65 20 64 61 74 ime that the dat 0430: 61 62 61 73 65 20 69 73 20 61 63 63 65 73 73 65 abase is accesse 0440: 64 2e 0a 3c 2f 70 3e 0a 0a 3c 70 3e 0a 41 20 63 d..</p>..<p>.A c 0450: 68 65 63 6b 2d 69 6e 20 6f 70 65 72 61 74 69 6f heck-in operatio 0460: 6e 20 69 6e 20 66 6f 73 73 69 6c 20 6d 61 6b 65 n in fossil make 0470: 73 20 6d 61 6e 79 20 63 68 61 6e 67 65 73 20 74 s many changes t 0480: 6f 20 74 68 65 20 72 65 70 6f 73 69 74 6f 72 79 o the repository 0490: 0a 64 61 74 61 62 61 73 65 2e 20 20 42 75 74 20 .database. But 04a0: 61 6c 6c 20 74 68 65 73 65 20 63 68 61 6e 67 65 all these change 04b0: 73 20 68 61 70 70 65 6e 20 77 69 74 68 69 6e 20 s happen within 04c0: 61 20 73 69 6e 67 6c 65 20 74 72 61 6e 73 61 63 a single transac 04d0: 74 69 6f 6e 2e 0a 49 66 20 73 6f 6d 65 74 68 69 tion..If somethi 04e0: 6e 67 20 67 6f 65 73 20 77 72 6f 6e 67 20 69 6e ng goes wrong in 04f0: 20 74 68 65 20 6d 69 64 64 6c 65 20 6f 66 20 74 the middle of t 0500: 68 65 20 63 6f 6d 6d 69 74 2c 20 74 68 65 6e 20 he commit, then 0510: 74 68 65 20 74 72 61 6e 73 61 63 74 69 6f 6e 0a the transaction. 0520: 69 73 20 72 6f 6c 6c 65 64 20 62 61 63 6b 20 61 is rolled back a 0530: 6e 64 20 74 68 65 20 64 61 74 61 62 61 73 65 20 nd the database 0540: 69 73 20 75 6e 63 68 61 6e 67 65 64 2e 0a 3c 2f is unchanged..</ 0550: 70 3e 0a 0a 3c 68 32 3e 56 65 72 69 66 69 63 61 p>..<h2>Verifica 0560: 74 69 6f 6e 20 4f 66 20 44 65 6c 74 61 20 45 6e tion Of Delta En 0570: 63 6f 64 69 6e 67 73 20 50 72 69 6f 72 20 54 6f codings Prior To 0580: 20 54 72 61 6e 73 61 63 74 69 6f 6e 20 43 6f 6d Transaction Com 0590: 6d 69 74 3c 2f 68 32 3e 0a 0a 3c 70 3e 0a 54 68 mit</h2>..<p>.Th 05a0: 65 20 63 6f 6e 74 65 6e 74 20 66 69 6c 65 73 20 e content files 05b0: 74 68 61 74 20 63 6f 6d 70 72 69 73 65 20 74 68 that comprise th 05c0: 65 20 67 6c 6f 62 61 6c 20 73 74 61 74 65 20 6f e global state o 05d0: 66 20 61 20 66 6f 73 73 69 6c 20 72 65 73 70 6f f a fossil respo 05e0: 73 69 74 6f 72 79 0a 61 72 65 20 73 74 6f 72 65 sitory.are store 05f0: 64 20 69 6e 20 74 68 65 20 72 65 70 6f 73 69 74 d in the reposit 0600: 6f 72 79 20 61 73 20 61 20 74 72 65 65 2e 20 20 ory as a tree. 0610: 54 68 65 20 6c 65 61 76 65 73 20 6f 66 20 74 68 The leaves of th 0620: 65 20 74 72 65 65 20 61 72 65 0a 73 74 6f 72 65 e tree are.store 0630: 64 20 61 73 20 7a 6c 69 62 2d 63 6f 6d 70 72 65 d as zlib-compre 0640: 73 73 65 64 20 42 4c 4f 42 73 2e 20 20 49 6e 74 ssed BLOBs. Int 0650: 65 72 69 6f 72 20 6e 6f 64 65 73 20 61 72 65 20 erior nodes are 0660: 64 65 6c 74 61 73 20 66 72 6f 6d 20 74 68 65 69 deltas from thei 0670: 72 0a 64 65 63 65 6e 64 65 6e 74 73 2e 20 20 54 r.decendents. T 0680: 68 65 72 65 20 69 73 20 61 20 6c 6f 74 20 6f 66 here is a lot of 0690: 20 65 6e 63 6f 64 69 6e 67 20 67 6f 69 6e 67 20 encoding going 06a0: 6f 6e 20 68 65 72 65 2e 20 20 54 68 65 72 65 20 on here. There 06b0: 69 73 0a 7a 6c 69 62 2d 63 6f 6d 70 72 65 73 73 is.zlib-compress 06c0: 69 6f 6e 20 77 68 69 63 68 20 69 73 20 72 65 6c ion which is rel 06d0: 61 74 69 76 65 6c 79 20 77 65 6c 6c 2d 74 65 73 atively well-tes 06e0: 74 65 64 20 62 75 74 20 73 74 69 6c 6c 20 6d 69 ted but still mi 06f0: 67 68 74 0a 63 61 75 73 65 20 63 6f 72 72 75 70 ght.cause corrup 0700: 74 69 6f 6e 20 69 66 20 75 73 65 64 20 69 6d 70 tion if used imp 0710: 72 6f 70 65 72 6c 79 2e 20 20 41 6e 64 20 74 68 roperly. And th 0720: 65 72 65 20 69 73 20 74 68 65 20 72 65 6c 61 74 ere is the relat 0730: 69 76 65 6c 79 0a 6e 65 77 20 64 65 6c 74 61 2d ively.new delta- 0740: 65 6e 63 6f 64 69 6e 67 20 6d 65 63 68 61 6e 69 encoding mechani 0750: 73 6d 20 64 65 73 69 67 6e 65 64 20 65 78 70 72 sm designed expr 0760: 65 73 73 6c 79 20 66 6f 72 20 66 6f 73 73 69 6c essly for fossil 0770: 2e 20 20 57 65 20 77 61 6e 74 0a 74 6f 20 6d 61 . We want.to ma 0780: 6b 65 20 73 75 72 65 20 74 68 61 74 20 62 75 67 ke sure that bug 0790: 73 20 69 6e 20 74 68 65 73 65 20 65 6e 63 6f 64 s in these encod 07a0: 69 6e 67 20 6d 65 63 68 61 6e 69 73 6d 73 20 64 ing mechanisms d 07b0: 6f 20 6e 6f 74 20 6c 65 61 64 20 74 6f 0a 6c 6f o not lead to.lo 07c0: 73 73 20 6f 66 20 64 61 74 61 2e 0a 3c 2f 70 3e ss of data..</p> 07d0: 0a 0a 3c 70 3e 0a 54 6f 20 69 6e 63 72 65 61 73 ..<p>.To increas 07e0: 65 20 6f 75 72 20 63 6f 6e 66 69 64 65 6e 63 65 e our confidence 07f0: 20 74 68 61 74 20 65 76 65 72 79 74 68 69 6e 67 that everything 0800: 20 69 6e 20 74 68 65 20 72 65 70 6f 73 69 74 6f in the reposito 0810: 72 79 20 69 73 0a 72 65 63 6f 76 65 72 61 62 6c ry is.recoverabl 0820: 65 2c 20 66 6f 73 73 69 6c 20 6d 61 6b 65 73 20 e, fossil makes 0830: 73 75 72 65 20 69 74 20 63 61 6e 20 65 78 74 72 sure it can extr 0840: 61 63 74 20 61 6e 20 65 78 61 63 74 20 72 65 70 act an exact rep 0850: 6c 69 63 61 74 65 0a 6f 66 20 65 76 65 72 79 20 licate.of every 0860: 63 6f 6e 74 65 6e 74 20 66 69 6c 65 20 74 68 61 content file tha 0870: 74 20 69 74 20 63 68 61 6e 67 65 73 20 6a 75 73 t it changes jus 0880: 74 20 70 72 69 6f 72 20 74 6f 20 74 72 61 6e 73 t prior to trans 0890: 61 63 74 69 6f 6e 0a 63 6f 6d 6d 69 74 2e 20 20 action.commit. 08a0: 53 6f 20 64 75 72 69 6e 67 20 74 68 65 20 63 6f So during the co 08b0: 75 72 73 65 20 6f 66 20 63 68 65 63 6b 2d 69 6e urse of check-in 08c0: 2c 20 6d 61 6e 79 20 64 69 66 66 65 72 65 6e 74 , many different 08d0: 20 66 69 6c 65 73 0a 69 6e 20 74 68 65 20 72 65 files.in the re 08e0: 70 6f 73 69 74 6f 72 79 20 6d 69 67 68 74 20 62 pository might b 08f0: 65 20 6d 6f 64 69 66 69 65 64 2e 20 20 53 6f 6d e modified. 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