mongodump big bug

[Thomas]

Hello,

I have a big backup issue with mongo 2.2 under ubuntu 12.04.

When I backup my whole database (mongodump on the db) it badly exports some of my collections (the metadata contains undefined values)

Exemple:

> db.testairq.stats()

{

"ns" : "test.testairq",

"count" : 0,

"size" : 0,

"storageSize" : 5713248256,

"numExtents" : 32,

"nindexes" : 1,

"lastExtentSize" : 961069056,

"paddingFactor" : 1.5299999998863023,

"systemFlags" : 0,

"userFlags" : 0,

"totalIndexSize" : 8176,

"indexSizes" : {

"_id.loc___id.time_1" : 8176

},

"ok" : 1

}

And the resulted metadata :

{options : { "create" : "testairq", undefined, undefined, undefined, "autoIndexId" : false }, indexes:[{ "v" : 1, "key" : { "_id.loc" : "2d", "_id.time" : 1 }, "unique" : true, "ns" : "test.testairq", "name" : "_id.loc___id.time_1", "sparse" : true }]}

mongorestore failed then to restore with this message

Wed Sep  5 16:17:12 dump/test/testairq.bson

Wed Sep  5 16:17:12 going into namespace [test.testairq]

Wed Sep  5 16:17:12   Assertion failure b.empty() src/mongo/db/json.cpp 645

0xad2211 0x67fced 0xa7daa5 0x56aa20 0x569cd1 0x569cd1 0x56db4a 0xb3b078 0xb41712 0x553f92 0x7f3a3c43076d 0x553e09 

 mongorestore(_ZN5mongo15printStackTraceERSo+0x21) [0xad2211]

 mongorestore(_ZN5mongo12verifyFailedEPKcS1_j+0xfd) [0x67fced]

 mongorestore(_ZN5mongo8fromjsonEPKcPi+0x585) [0xa7daa5]

 mongorestore(_ZN7Restore9drillDownEN5boost11filesystem210basic_pathISsNS1_11path_traitsEEEbbb+0xff0) [0x56aa20]

 mongorestore(_ZN7Restore9drillDownEN5boost11filesystem210basic_pathISsNS1_11path_traitsEEEbbb+0x2a1) [0x569cd1]

 mongorestore(_ZN7Restore9drillDownEN5boost11filesystem210basic_pathISsNS1_11path_traitsEEEbbb+0x2a1) [0x569cd1]

 mongorestore(_ZN7Restore5doRunEv+0xdda) [0x56db4a]

 mongorestore(_ZN5mongo8BSONTool3runEv+0x448) [0xb3b078]

 mongorestore(_ZN5mongo4Tool4mainEiPPc+0x1712) [0xb41712]

 mongorestore(main+0x32) [0x553f92]

 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed) [0x7f3a3c43076d]

 mongorestore(__gxx_personality_v0+0x421) [0x553e09]

assertion: 0 assertion src/mongo/db/json.cpp:645

Is this a known bug or do I have to open a new issue ?

It's really a big issue since my backup system is totally based on this mechanism.

Thank you,

Thomas.

[Mathias Stearn]

What does db.system.namespaces.find() say?

[Thomas]

I don't have any namespaces in the system collection ...

[Mathias Stearn]

Every database has a system.namespaces collection. Note that there is no "systems" collection, the actual name of the collection is "system.namespaces". Please try running db.system.namespaces.find()

[Thomas]

Indeed (i just thought that, because the completion on the console did not work for namespaces) :)

Well for the collection message_queue i have this metadata genrated by mongodump:

{options : { "create" : "message_queue", "capped" : true, "size" : 1024, undefined }, indexes:[{ "v" : 1, "key" : { "time" : 1 }, "unique" : true, "ns" : "nadb.message_queue", "sparse" : true, "name" : "time_1" }]}

And in the db.system.namespaces.find() : (for our message_queue part only)

{ "name" : "nadb.message_queue", "options" : { "create" : "message_queue", "capped" : true, "size" : 1024, "max" : null } }

{ "name" : "nadb.message_queue.$time_1" }

db.message_queue.stats() produces :

> db.message_queue.stats()

{

"ns" : "nadb.message_queue",

"count" : 63,

"size" : 2796,

"avgObjSize" : 44.38095238095238,

"storageSize" : 4096,

"numExtents" : 1,

"nindexes" : 1,

"lastExtentSize" : 4096,

"paddingFactor" : 1,

"systemFlags" : 0,

"userFlags" : 0,

"totalIndexSize" : 8176,

"indexSizes" : {

"time_1" : 8176

},

"capped" : true,

"max" : 2147483647,

"ok" : 1

}

Thank you,

Thomas.

[Mathias Stearn]

I've tracked this down to something that was recently fixed in master: https://jira.mongodb.org/browse/SERVER-7104. I requested that it be backported to 2.2.

For now, a possible workaround would be to manually edit the json files to remove the offending undefineds.

[Ketema Harris]

I found that if I manually edit the file manually to remove undefined, the restore still fails with:

User Assertion: 15934:JSON object size didn't match file size