Merge latest wal2 changes with this branch.

FossilOrigin-Name: ea96001e801fbf228d1fb63b9d3c73fd9da54994d3cfe383ea76edfa6da83b8d

diff --cc ext/session/sqlite3session.h
Simple merge

diff --cc manifest
index 4bc575194a060923d2bbc7da8767814776d7c736,80a2f721d2d5a8cc4efe445be0ccbfe3aedd42ae..150a647bf7028f578fce5ddeab16621c875d49a2
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Merge\slatest\strunk\schanges\sinto\sthis\sbranch.
- D 2018-12-18T17:32:08.747
 -C Increase\stest\scoverage\sof\swal.c\sprovided\sby\spermutation\s"coverage-wal"\son\sthis\nbranch.
 -D 2018-12-27T16:49:33.954
++C Merge\slatest\swal2\schanges\swith\sthis\sbranch.
++D 2018-12-27T17:11:59.756
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F Makefile.in d8b254f8bb81bab43c340d70d17dc3babab40fcc8a348c8255881f780a45fee6
@@@ -423,11 -424,9 +426,11 @@@ F ext/session/sessioninvert.test ae1a00
  F ext/session/sessionrebase.test ccfa716b23bd1d3b03217ee58cfd90c78d4b99f53e6a9a2f05e82363b9142810
  F ext/session/sessionstat1.test 218d351cf9fcd6648f125a26b607b140310160184723c2666091b54450a68fb5
  F ext/session/sessionwor.test 07f0b304dc4df5454906069140bf6ec67edcaa3c548f3683354003cf2c22b64a
 -F ext/session/sqlite3session.c f88c4bd0404da56246b08f5d584462f8979ba6aedf8c30762b553f7ae91f51cf
 -F ext/session/sqlite3session.h 54d6356f5769d3695e5f63d719c6ee27671b2614973a2b675a3ff4d30d574233
 -F ext/session/test_session.c 98797aba475a799376c9a42214f2d1debf2d0c3cb657d9c8bbf4f70bf3fb4aec
 +F ext/session/sqlite3changebatch.c d5553b79e012ee2cb06c0a96bdf9dfe19e66354390ea0036cc46c4953142d517
 +F ext/session/sqlite3changebatch.h e72016998c9a22d439ddfd547b69e1ebac810c24
 +F ext/session/sqlite3session.c 994b1b691f3e1ab72a9d3949c2ca7dca4db3d9dd5ece5e34f74953411b8d36f9
- F ext/session/sqlite3session.h 2a449bb4ba954dd374bd8524af6187454f98fa1d61d16a9f6709ce0a191cf4f1
++F ext/session/sqlite3session.h fd5d353901575b587c877b957918ff9f2d8e0ff40a96b210cf79459c0e17d3b7
 +F ext/session/test_session.c 60e15d5db8ae7a0f521e70a7504ba1f74fc50548a25a5397808f487bc6a92b5d
  F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
  F ext/userauth/user-auth.txt e6641021a9210364665fe625d067617d03f27b04
  F ext/userauth/userauth.c f81aa5a3ecacf406f170c62a144405858f6f6de51dbdc0920134e629edbe2648
@@@ -451,12 -450,12 +454,12 @@@ F src/analyze.c 3dc6b98cf007b005af89df1
  F src/attach.c 92b51739a885da8bd84bc9a05485f1e48148bce5c15432f059b45af98fff75cd
  F src/auth.c 0fac71038875693a937e506bceb492c5f136dd7b1249fbd4ae70b4e8da14f9df
  F src/backup.c 78d3cecfbe28230a3a9a1793e2ead609f469be43e8f486ca996006be551857ab
 -F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 +F src/bitvec.c 8433d9e98dd6f2ea3286e0d2fe5d65de1bfc18a706486eb2026b01be066b5806
  F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 -F src/btree.c 5feb77070052b2cb9f6209e47a6a4de01b51d6fe2689bd56f6016faa22126826
 -F src/btree.h febb2e817be499570b7a2e32a9bbb4b607a9234f6b84bb9ae84916d4806e96f2
 -F src/btreeInt.h 620ab4c7235f43572cf3ac2ac8723cbdf68073be4d29da24897c7b77dda5fd96
 -F src/build.c cb86906fcc9150514024d74befa6905bce2323f51518cc5973e4be6a5b00fd16
 +F src/btree.c 3140a87697bdbb150eb57733421263011a19fc70752c7bde29c7ceff7a2133d3
 +F src/btree.h 1ed41c71481a1196a520064f2282bc13d768bbd8ae2850e319a3048f8ee7cb3d
 +F src/btreeInt.h 6c65e6c96f561596f6870c79a64d4706af81613881d7947e3f063e923f14115f
- F src/build.c a5402bf34cb8e4cde86f6c6fc0356a5d26a6d561b647464c13ef3366f545b56e
++F src/build.c a1bfe29e9743620d036f1a07b2fee269832db462a5a36aa95f94b3725fde0cb8
  F src/callback.c 25dda5e1c2334a367b94a64077b1d06b2553369f616261ca6783c48bcb6bda73
  F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
  F src/ctime.c 109e58d00f62e8e71ee1eb5944ac18b90171c928ab2e082e058056e1137cc20b
@@@ -473,10 -472,10 +476,10 @@@ F src/hash.c a12580e143f10301ed5166ea49
  F src/hash.h ab34c5c54a9e9de2e790b24349ba5aab3dbb4fd4
  F src/hwtime.h 747c1bbe9df21a92e9c50f3bbec1de841dc5e5da
  F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
- F src/insert.c f12f27eb606d601825be9a229a7390a8d64d40226697883f96de8e088d620055
+ F src/insert.c 2b5d4e52fdcf1b9e8a5fe88bb2a5f1c58338062145b95683c2e98467633620e8
  F src/legacy.c 134ab3e3fae00a0f67a5187981d6935b24b337bcf0f4b3e5c9fa5763da95bf4e
  F src/loadext.c e6f10875d52aca3b7e57ce1ec174aeafc9b6c00b43000cd30d791f9cb490b7a6
 -F src/main.c 008f45dd39cdc7fb9e7e1f61d75a5c97397f8e07427a8879be23e27747d5f948
 +F src/main.c c96ec2fffaf1c3963b31be1d378defd205228fa628522f49a6dd48d99d901851
  F src/malloc.c 07295435093ce354c6d9063ac05a2eeae28bd251d2e63c48b3d67c12c76f7e18
  F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
  F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@@ -514,10 -513,10 +517,10 @@@ F src/resolve.c 72fe8cae7326b979e7258ab
  F src/rowset.c d977b011993aaea002cab3e0bb2ce50cf346000dff94e944d547b989f4b1fe93
  F src/select.c 8c7317d5ee920516a56b8b4ca79fbfca70a1f8b52d67e884c808ea3a016c04e3
  F src/shell.c.in 207da30342db0b6fac8b2487abd60b059a5ea80cc9494bd1db76a1dd4aae7cca
- F src/sqlite.h.in 846968c2880c2223e0d65c544698fedcf45bbddc52693a9b020519725690e1fd
 -F src/sqlite.h.in b54cd42d2f3b739a00de540cafe2dcd0de3b8e1748a2db33a68def487e9e602f
++F src/sqlite.h.in a8ac449be3b5f7edeaf9066bec560323a61fcd032f199f7f462444afda119151
  F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
  F src/sqlite3ext.h 960f1b86c3610fa23cb6a267572a97dcf286e77aa0dd3b9b23292ffaa1ea8683
- F src/sqliteInt.h 6b99bba999b415775ddecb02298902a766e93e620a72a282d0db67534743478e
 -F src/sqliteInt.h 031e09cf6ea600e23fb4ce6e0a81f3f0e256b990dc6a71d21324d9ab8533b6cd
++F src/sqliteInt.h f055700619aff4d6f6dba2f09dfc1f98ae501a26a737ef9dab680ef9aeb42f36
  F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
  F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
  F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@@ -582,20 -581,20 +585,20 @@@ F src/update.c 1816d56c1bca1ba4e0ef98ca
  F src/upsert.c 0dd81b40206841814d46942a7337786932475f085716042d0cb2fc7791bf8ca4
  F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5
  F src/util.c d9eb0a6c4aae1b00a7369eadd7ca0bbe946cb4c953b6751aa20d357c2f482157
 -F src/vacuum.c 3ffe64ecfc94b7528c5d7bdb1c3a19d72fec63f2aa846e3b90f8de5dbbddf5aa
 -F src/vdbe.c f71d8ca9a293c99548dfcc0b93cf874bcbf877db30653be71334ac5959b63cdf
 +F src/vacuum.c ae2152420bad05336d86bb3b4a8a32ddb12b22ae19e5a976bee5f0a775429efb
- F src/vdbe.c 80b4a90624105b3ac1eb26192f1fe7f3f67421984b4e2d367cc21378794bb708
++F src/vdbe.c ba573da212e055550b797b52d7f7e415a84f6ba333c02db8429b097e2fbc43ed
  F src/vdbe.h 8990d668a89890a33326b0a29b992c4014b72f3b6cdcd9ee0e190593c247f9b0
  F src/vdbeInt.h 73f5051923f3f29779bfc374c0c68e23b8e5e3792def2e33e51b427edb890abd
  F src/vdbeapi.c 57a2d794a8833f269b878dbc24e955369bdb379af6c4e93ebc5ce1a20fa3daf4
- F src/vdbeaux.c 9f2a251e610ec962dca093e8d9644a5243be606c5f78a4a16582bd9edef50e1f
 -F src/vdbeaux.c ed00c59d24e2ffef24bddca98640195b14b196f1610eaf580c6ad7cfb73712c0
++F src/vdbeaux.c 408562b462ac83d68f038073b6c17ef069f99861729efdd82dd093b1f5dd1d07
  F src/vdbeblob.c f5c70f973ea3a9e915d1693278a5f890dc78594300cf4d54e64f2b0917c94191
  F src/vdbemem.c 7b3305bc4a5139f4536ac9b5f61da0f915e49d2e3fdfa87dfdfa9d7aba8bc1e9
  F src/vdbesort.c 90aad5a92608f2dd771c96749beabdb562c9d881131a860a7a5bccf66dc3be7f
  F src/vdbetrace.c 79d6dbbc479267b255a7de8080eee6e729928a0ef93ed9b0bfa5618875b48392
  F src/vtab.c 70188a745dc4e57d26e942681ff4b2912b7c8249ad5de3f60f0677b4337bcfaa
  F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
- F src/wal.c 2640020e19d6d2f14ac02fdc468ea965388d956880221d4c8088f20077a85598
 -F src/wal.c 8bfa18a1c5e04a21a8cb142cdb7f8236ad32300a2298565b6fe1cdd15beee3a6
 -F src/wal.h d2a69695c84137f76e19a247a342cb02ab0131001b6f58153d94b71195bbd84d
++F src/wal.c 80b66beb428e6e99abbb3ebc924bf8121936d0185d74931b50ff667779574f09
 +F src/wal.h c398e0269e8f37495cedb63b5e288c2aac6f6d103d05fb55f4affec21311615d
  F src/walker.c fb94aadc9099ff9c6506d0a8b88d51266005bcaa265403f3d7caf732a562eb66
  F src/where.c 3818e8a736a05d2cb194e64399af707e367fbcc5c251d785804d02eaf121288e
  F src/whereInt.h f125f29fca80890768e0b2caa14f95db74b2dacd3a122a168f97aa7b64d6968f
@@@ -731,15 -729,7 +734,15 @@@ F test/collateA.test b8218ab90d1fa5c59d
  F test/collateB.test 1e68906951b846570f29f20102ed91d29e634854ee47454d725f2151ecac0b95
  F test/colmeta.test 2c765ea61ee37bc43bbe6d6047f89004e6508eb1
  F test/colname.test fb28b3687e03625425bc216edf8b186ce974aa71008e2aa1f426a7dcb75a601d
- F test/conflict.test 029faa2d81a0d1cafb5f88614beb663d972c01db
 +F test/concfault.test 500f17c3fcfe7705114422bcc6ddd3c740001a43
 +F test/concurrent.test 86661967a680670127a62a819e60dc93c2d3d49043ac95b26dfa70d3e60dbde5
 +F test/concurrent2.test 9dfbeb0a323733fe1d13443371734bb94a674dbf777f464365475903873111f8
 +F test/concurrent3.test 530671ac706f6a1d0f4992dbdd33a86408330d03cd90fb9e82ecb1b27f5fd081
 +F test/concurrent4.test e0b12cd467137e50259df3b4f837507e82aaa07c35941c88664dc8ed1d089c44
 +F test/concurrent5.test 0c16cbf7446af162a14e6def30445e94016064eb994e5aa4ebb2bebc59554176
 +F test/concurrent6.test a7860e9ca13bb5fb76bcf41c5524fbfa9c37e6e258ecf84ffb5748a272488c67
 +F test/concurrent7.test b96fa5c4cfdf8d5c0bc66b6934214500bad0260884a736f054ccc76e81aae85d
+ F test/conflict.test c7cc007e2af151516ddf38f7412fe10d473a694f55e3df437e2c7b31c2590e8d
  F test/conflict2.test bb0b94cf7196c64a3cbd815c66d3ee98c2fecd9c
  F test/conflict3.test a83db76a6c3503b2fa057c7bfb08c318d8a422202d8bc5b86226e078e5b49ff9
  F test/contrib01.test 2a1cbc0f2f48955d7d073f725765da6fbceda6b4
@@@ -1196,7 -1187,8 +1200,7 @@@ F test/pagesize.test 5769fc62d8c890a83a
  F test/pcache.test c8acbedd3b6fd0f9a7ca887a83b11d24a007972b
  F test/pcache2.test af7f3deb1a819f77a6d0d81534e97d1cf62cd442
  F test/percentile.test 4243af26b8f3f4555abe166f723715a1f74c77ff
- F test/permutations.test 2a639a69a3ddee195b36cb5118e7a6ac2a1a0a320b08fdbb32239bf88189ec30
 -F test/permutations.test 027d8460ba7a2e7b1332388c81fc896f713e1bba57c7157a8278b6bdfd321111
++F test/permutations.test 2ef576293b632574521da217837c185b839b5e5edf379a78261facf4250bba07
  F test/pg_common.tcl 301ac19c1a52fd55166d26db929b3b89165c634d52b5f8ad76ea8cb06960db30
  F test/pragma.test c267bf02742c823a191960895b3d52933cebd7beee26757d1ed694f213fcd867
  F test/pragma2.test e5d5c176360c321344249354c0c16aec46214c9f
@@@ -1547,13 -1540,12 +1552,13 @@@ F test/trigger8.test 30cb0530bd7c472805
  F test/trigger9.test 2226ec795a33b0460ab5cf8891e9054cc7edef41
  F test/triggerA.test 837be862d8721f903dba3f3ceff05b32e0bee5214cf6ea3da5fadf12d3650e9d
  F test/triggerB.test 56780c031b454abac2340dbb3b71ac5c56c3d7fe
- F test/triggerC.test 302d8995f5ffe63bbc15053abb3ef7a39cf5a092
+ F test/triggerC.test c7fbc3eb241b5a7ba4b0815f76c3708483e91890f9573add12a610c45b2a6022
  F test/triggerD.test 8e7f3921a92a5797d472732108109e44575fa650
  F test/triggerE.test ede2e4bce4ba802337bd69d39447fa04a938e06d84a8bfc53c76850fc36ed86d
- F test/triggerF.test 6a8c22bd058cf467f0c7d112afe87f7a8c579c0c4681b914b8f19020f48528a4
+ F test/triggerF.test 5d76f0a8c428ff87a4d5ed52da06f6096a2c787a1e21b846111dfac4123de3ad
  F test/triggerG.test d5caeef6144ede2426dd13211fd72248241ff2ebc68e12a4c0bf30f5faa21499
  F test/tt3_checkpoint.c 9e75cf7c1c364f52e1c47fd0f14c4340a9db0fe1
 +F test/tt3_core.c 8cd89ead95410f70e7fb02c79f1e040f9c5ad5cf
  F test/tt3_index.c 39eec10a35f57672225be4d182862152896dee4a
  F test/tt3_lookaside1.c 0377e202c3c2a50d688cb65ba203afeda6fafeb9
  F test/tt3_stress.c c57d804716165811d979d4a719e05baccd79277f
@@@ -1609,17 -1601,17 +1614,18 @@@ F test/vtabJ.test d7b73675708cf63cfcb9d
  F test/vtab_alter.test 736e66fb5ec7b4fee58229aa3ada2f27ec58bc58c00edae4836890c3784c6783
  F test/vtab_err.test dcc8b7b9cb67522b3fe7a272c73856829dae4ab7fdb30399aea1b6981bda2b65
  F test/vtab_shared.test 5253bff2355a9a3f014c15337da7e177ab0ef8ad
- F test/wal.test 613efec03e517e1775d86b993a54877d2e29a477
+ F test/wal.test a233cd4733928a5aaef24738727c4094d561ea68089f93cccd1f6e9dec610212
 -F test/wal2.test 155b9efa999bdb38ce1cd729b9a4fcdbffd6b88be27f039bad1d2929d287d918
 +F test/wal2.test a225bafac35a47765b890bacdeb57e5e81039f21cc18a1e8ce88eb76e56b843c
  F test/wal2big.test 0b4ec526f9ca4bbabc355042c38045ae2e253fb46eb327bb7693d0122bc6968b
 +F test/wal2concurrent.test 7fc3e570073683a2a28f42bda46ecf516f5bc82afd703c1fbf4aa38e18fb3361
+ F test/wal2fault.test 2e8e60cacd5bcd451618aeffd05f676894d17202d3e2986e288d36e2c5993249
  F test/wal2lock.test 0ef98d72dc6bcf7711dedd684760488400d9a9a6eec0dc5d3822060437793552
  F test/wal2recover.test ba8f4bc9397c838734619f9e759bd98b00e355347b3cf80a2e677610d231d5d8
 -F test/wal2recover2.test d473784bc72ee70438d1aa1cbe449fb322d7e52e8eaa256135fb3182c66b1c78
 +F test/wal2recover2.test 3176a03eccebb203e5c5635d94624bf573392fccb3f9d39d9d9a27aab96e4c88
  F test/wal2rewrite.test 6ca6f631ffcf871240beab5f02608913fd075c6d0d31310b026c8383c65c9f9c
 -F test/wal2savepoint.test 2c82bd6a6ee5066c156040d2e9c2415646fcf96116ae7ad127eaf0c0b4a85f22
 +F test/wal2savepoint.test 29725383e7eb8b78fed46333d69dc45b4ed321db43ecc81766aadea991874bef
  F test/wal2simple.test 96206c98bf64ab20ec00a1c0f6c709e258b98b39f2149889361f31966ce5a703
 -F test/wal2snapshot.test 7a5f4629a3c43a43c3440b8b2ea9f07de91a46b0b9eea5f08f62b5bf5b6468df
 +F test/wal2snapshot.test 95a919e1c73dee0e0212d10931d03cc1116f68a0ff603163e551aaa5ac7025c1
  F test/wal3.test 2a93004bc0fb2b5c29888964024695bade278ab2
  F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
  F test/wal5.test 9c11da7aeccd83a46d79a556ad11a18d3cb15aa9
@@@ -1812,7 -1804,7 +1820,7 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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  U dan
- Z a47178a1de728bf0e9a383c129165be6
 -Z 537fbe586afdb7bdeed308e7bd56f47e
++Z 04d8d4c3b9345edf2ad657de9636b01f

diff --cc manifest.uuid
index df45b7c9cea15279d9cf394b5526911e4b94ea3f,f8fc8d6c56cb56fcd987b2480ca4007e50a669c1..2195f75437eadf77df2f8947590f1acc27e4ba98
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- b3a163b46cad19a2e6a90cdd5b4c2e94d66e80b7ad2a0c9857580fe74748a604
 -2f7f893a702728745445f6ef5f914c1157058a8fbdfd1a58cfb8906e5566729d
++ea96001e801fbf228d1fb63b9d3c73fd9da54994d3cfe383ea76edfa6da83b8d

diff --cc src/build.c
Simple merge

diff --cc src/sqlite.h.in
Simple merge

diff --cc src/sqliteInt.h
Simple merge

diff --cc src/vdbe.c
Simple merge

diff --cc src/vdbeaux.c
Simple merge

diff --cc src/wal.c
index b7e2391041cf22d54876d5fbe5ef6d41f05c8a5c,b90ba4df1a904b714a9370b1c10ff58882db4bbb..288bd0cb9d2f5ad32e7a9bb799486942b1a37c16
--- 1/src/wal.c
--- 2/src/wal.c
+++ b/src/wal.c
@@@ -305,6 -305,31 +305,32 @@@
  **
  ** The first wal file takes the same name as the wal file in legacy wal
  ** mode systems - "<db>-wal". The second is named "<db>-wal2".
++
+ **
+ ** CHECKPOINTS
+ **
+ ** The "pre-configured size" mentioned above is the value set by 
+ ** "PRAGMA journal_size_limit". Or, if journal_size_limit is not set, 
+ ** 1000 pages.
+ **
+ ** There is only a single type of checkpoint in wal2 mode (no "truncate",
+ ** "restart" etc.), and it always checkpoints the entire contents of a single
+ ** wal file. A wal file cannot be checkpointed until after a writer has written
+ ** the first transaction into the other wal file and all readers are reading a
+ ** snapshot that includes at least one transaction from the other wal file.
+ **
+ ** The wal-hook, if one is registered, is invoked after a write-transaction
+ ** is committed, just as it is in legacy wal mode. The integer parameter
+ ** passed to the wal-hook is the total number of uncheckpointed frames in both
+ ** wal files. Except, the parameter is set to zero if there is no frames 
+ ** that may be checkpointed. This happens in two scenarios:
+ **
+ **   1. The "other" wal file (the one that the writer did not just append to)
+ **      is completely empty, or
+ **
+ **   2. The "other" wal file (the one that the writer did not just append to)
+ **      has already been checkpointed.
+ **
  **
  ** WAL FILE FORMAT
  **
@@@ -3570,26 -3577,20 +3596,28 @@@ int sqlite3WalFindFrame
    int rc = SQLITE_OK;
    u32 iRead = 0;                  /* If !=0, WAL frame to return data from */
  
-   /* This routine is only be called from within a read transaction. */
-   assert( pWal->readLock!=WAL_LOCK_NONE );
+   /* This routine is only be called from within a read transaction. Or,
+   ** sometimes, as part of a rollback that occurs after an error reaquiring
+   ** a read-lock in walRestartLog().  */
+   assert( pWal->readLock!=WAL_LOCK_NONE || pWal->writeLock );
  
 -  /* If this is a wal2 system, the client must have a partial-wal lock 
 -  ** on wal file iApp. Or if it is a wal system, iApp==0 must be true.  */
 -  assert( bWal2==0 || iApp==1
 -       || pWal->readLock==WAL_LOCK_PART1 || pWal->readLock==WAL_LOCK_PART1_FULL2
 -  );
 -  assert( bWal2==0 || iApp==0
 -       || pWal->readLock==WAL_LOCK_PART2 || pWal->readLock==WAL_LOCK_PART2_FULL1
 -  );
 -  assert( bWal2 || iApp==0 );
 +  /* If this is a regular wal system, then iApp must be set to 0 (there is
 +  ** only one wal file, after all). Or, if this is a wal2 system and the
 +  ** write-lock is not held, the client must have a partial-wal lock on wal 
 +  ** file iApp. This is not always true if the write-lock is held and this
 +  ** function is being called after WalLockForCommit() as part of committing
 +  ** a CONCURRENT transaction.  */
 +#ifdef SQLITE_DEBUG
 +  if( bWal2 ){
 +    if( pWal->writeLock==0 ){
 +      int l = pWal->readLock;
 +      assert( iApp==1 || l==WAL_LOCK_PART1 || l==WAL_LOCK_PART1_FULL2 );
 +      assert( iApp==0 || l==WAL_LOCK_PART2 || l==WAL_LOCK_PART2_FULL1 );
 +    }
 +  }else{
 +    assert( iApp==0 );
 +  }
 +#endif
  
    /* Return early if read-lock 0 is held. */
    if( (pWal->readLock==0 && pWal->bShmUnreliable==0) ){
@@@ -4667,8 -4428,10 +4696,8 @@@ int sqlite3WalCheckpoint
  
    /* Copy data from the log to the database file. */
    if( rc==SQLITE_OK ){
 -    int iCkpt = walidxGetFile(&pWal->hdr);
 -
      if( (walPagesize(pWal)!=nBuf) 
-      && (walidxGetMxFrame(&pWal->hdr, 0) || walidxGetMxFrame(&pWal->hdr, 1))
+      && ((pWal->hdr.mxFrame2 & 0x7FFFFFFF) || pWal->hdr.mxFrame)
      ){
        rc = SQLITE_CORRUPT_BKPT;
      }else{

diff --cc test/permutations.test
index d7c03fd329c0fc387ce37586bed5c4a34eb2cab0,5dc203d80cfdc85fe24ede1a8c6caa3c7ec447a8..c0a2c2ef90f6a57cb6e3c9aede1b8dd71fd41574
--- 1/test/permutations.test
--- 2/test/permutations.test
+++ b/test/permutations.test
@@@ -430,21 -430,21 +430,27 @@@ lappend ::testsuitelist xx
  test_suite "coverage-wal" -description {
    Coverage tests for file wal.c.
  } -files {
 -  wal2big.test wal2recover.test wal2rewrite.test
 -  wal2simple.test wal2snapshot.test wal2.test
 -  wal3.test wal4.test wal5.test
 -  wal64k.test wal6.test wal7.test wal8.test wal9.test
 -  walbak.test walbig.test walblock.test walcksum.test 
 -  walfault.test walhook.test walmode.test walnoshm.test
 -  waloverwrite.test walpersist.test walprotocol2.test
 -  walprotocol.test walro2.test walrofault.test walro.test
 -  walshared.test walslow.test wal.test
 -  wal2savepoint.test wal2lock.test wal2recover2.test
 +wal2big.test wal2recover.test wal2rewrite.test
 +wal2simple.test wal2snapshot.test wal2.test
 +wal3.test wal4.test wal5.test
 +wal64k.test wal6.test wal7.test wal8.test wal9.test
 +walbak.test walbig.test walblock.test walcksum.test 
 +walfault.test walhook.test walmode.test walnoshm.test
 +waloverwrite.test walpersist.test walprotocol2.test
 +walprotocol.test walro2.test walrofault.test walro.test
 +walshared.test walslow.test wal.test
 +wal2savepoint.test wal2lock.test wal2recover2.test
 +
- wal2concurrent.test
- concurrent.test concurrent2.test concurrent3.test
- concurrent4.test concurrent5.test concurrent6.test
- concurrent7.test
++  wal2concurrent.test
++  concurrent.test concurrent2.test concurrent3.test
++  concurrent4.test concurrent5.test concurrent6.test
++  concurrent7.test
++
+   walvfs.test walfault2.test nockpt.test
+   snapshot2.test snapshot3.test snapshot4.test
+   snapshot_fault.test snapshot.test snapshot_up.test
+   walcrash2.test walcrash3.test walcrash4.test walcrash.test
+   wal2fault.test
  } 
  
  test_suite "coverage-pager" -description {