Details
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Bug
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Resolution: Done
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Trivial - P5
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2.6.5, 2.8.0-rc0
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Fully Compatible
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ALL
Description
Running db.coll.stats() with mmapv1 gives following result:
db.foo.stats()
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{
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"ns" : "test.foo",
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"count" : 1,
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"size" : 48,
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"avgObjSize" : 48,
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"storageSize" : 8192,
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"numExtents" : 1,
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"nindexes" : 1,
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"lastExtentSize" : 8192,
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"paddingFactor" : 1,
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"systemFlags" : 1,
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"userFlags" : 1,
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"totalIndexSize" : 8176,
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"indexSizes" : {
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"_id_" : 8176
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},
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"ok" : 1
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}
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- with wiredtiger it gives:
> db.foo.stats()
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{
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"ns" : "test.foo",
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"count" : 1,
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"size" : 33,
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"avgObjSize" : 33,
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"storageSize" : 16384,
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"nindexes" : 1,
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"capped" : false,
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"wiredtiger" : {
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"uri" : "statistics:table:collection-4-3616236290870497461",
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"LSM" : {
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"bloom filters in the LSM tree" : 0,
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"bloom filter false positives" : 0,
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"bloom filter hits" : 0,
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"bloom filter misses" : 0,
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"bloom filter pages evicted from cache" : 0,
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"bloom filter pages read into cache" : 0,
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"total size of bloom filters" : 0,
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"sleep for LSM checkpoint throttle" : 0,
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"chunks in the LSM tree" : 0,
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"highest merge generation in the LSM tree" : 0,
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"queries that could have benefited from a Bloom filter that did not exist" : 0,
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"sleep for LSM merge throttle" : 0
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},
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"block-manager" : {
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"file allocation unit size" : 4096,
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"blocks allocated" : 3,
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"checkpoint size" : 8192,
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"allocations requiring file extension" : 3,
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"blocks freed" : 0,
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"file magic number" : 120897,
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"file major version number" : 1,
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"minor version number" : 0,
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"file bytes available for reuse" : 0,
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"file size in bytes" : 16384
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},
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"btree" : {
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"column-store variable-size deleted values" : 0,
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"column-store fixed-size leaf pages" : 0,
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"column-store internal pages" : 0,
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"column-store variable-size leaf pages" : 0,
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"pages rewritten by compaction" : 0,
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"number of key/value pairs" : 0,
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"fixed-record size" : 0,
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"maximum tree depth" : 3,
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"maximum internal page item size" : 384,
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"maximum internal page size" : 4096,
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"maximum leaf page item size" : 3072,
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"maximum leaf page size" : 32768,
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"overflow pages" : 0,
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"row-store internal pages" : 0,
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"row-store leaf pages" : 0
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},
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"cache" : {
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"bytes read into cache" : 0,
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"bytes written from cache" : 127,
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"checkpoint blocked page eviction" : 0,
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"unmodified pages evicted" : 0,
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"modified pages evicted" : 0,
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"data source pages selected for eviction unable to be evicted" : 0,
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"hazard pointer blocked page eviction" : 0,
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"internal pages evicted" : 0,
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"overflow values cached in memory" : 0,
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"pages read into cache" : 0,
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"overflow pages read into cache" : 0,
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"pages written from cache" : 2
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},
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"compression" : {
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"raw compression call failed, no additional data available" : 0,
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"raw compression call failed, additional data available" : 0,
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"raw compression call succeeded" : 0,
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"compressed pages read" : 0,
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"compressed pages written" : 0,
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"page written failed to compress" : 0,
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"page written was too small to compress" : 2
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},
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"cursor" : {
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"create calls" : 1,
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"insert calls" : 1,
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"bulk-loaded cursor-insert calls" : 0,
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"cursor-insert key and value bytes inserted" : 34,
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"next calls" : 0,
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"prev calls" : 1,
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"remove calls" : 0,
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"cursor-remove key bytes removed" : 0,
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"reset calls" : 2,
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"search calls" : 0,
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"search near calls" : 0,
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"update calls" : 0,
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"cursor-update value bytes updated" : 0
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},
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"reconciliation" : {
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"dictionary matches" : 0,
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"internal page multi-block writes" : 0,
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"leaf page multi-block writes" : 0,
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"maximum blocks required for a page" : 0,
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"internal-page overflow keys" : 0,
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"leaf-page overflow keys" : 0,
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"overflow values written" : 0,
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"pages deleted" : 0,
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"page checksum matches" : 0,
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"page reconciliation calls" : 2,
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"page reconciliation calls for eviction" : 0,
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"leaf page key bytes discarded using prefix compression" : 0,
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"internal page key bytes discarded using suffix compression" : 0
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},
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"session" : {
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"object compaction" : 0,
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"open cursor count" : 5
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},
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"transaction" : {
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"update conflicts" : 0
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}
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},
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"totalIndexSize" : 16384,
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"indexSizes" : {
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"_id_" : 16384
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},
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"ok" : 1
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}
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Notice that mmapv1 version is missing "capped" from the stats result.
The likely cause is the difference in following files:
https://github.com/mongodb/mongo/blob/master/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp (~ line 709)
https://github.com/mongodb/mongo/blob/master/src/mongo/db/storage/mmap_v1/record_store_v1_base.cpp ( ~ line 817)