Details
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Improvement
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Resolution: Works as Designed
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Major - P3
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None
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None
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None
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Fully Compatible
Description
I run `compact` command on a collection with stats as below.
SECONDARY> db.somecoll.stats()
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{
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"ns" : "dbdoc.somecoll", |
"count" : 221435, |
"size" : 29477552228, |
"avgObjSize" : 133120, |
"storageSize" : 107902332928, |
"capped" : false, |
"wiredTiger" : { |
"metadata" : { |
"formatVersion" : 1 |
},
|
"creationString" : "access_pattern_hint=none,allocation_size=4KB,app_metadata=(formatVersion=1),block_allocation=best,block_compressor=snappy,cache_resident=false,checksum=on,colgroups=,collator=,columns=,dictionary=0,encryption=(keyid=,name=),exclusive=false,extractor=,format=btree,huffman_key=,huffman_value=,ignore_in_memory_cache_size=false,immutable=false,internal_item_max=0,internal_key_max=0,internal_key_truncate=true,internal_page_max=4KB,key_format=q,key_gap=10,leaf_item_max=0,leaf_key_max=0,leaf_page_max=32KB,leaf_value_max=64MB,log=(enabled=true),lsm=(auto_throttle=true,bloom=true,bloom_bit_count=16,bloom_config=,bloom_hash_count=8,bloom_oldest=false,chunk_count_limit=0,chunk_max=5GB,chunk_size=10MB,merge_max=15,merge_min=0),memory_page_max=10m,os_cache_dirty_max=0,os_cache_max=0,prefix_compression=false,prefix_compression_min=4,source=,split_deepen_min_child=0,split_deepen_per_child=0,split_pct=90,type=file,value_format=u", |
"type" : "file", |
"uri" : "statistics:table:dbdoc/collection-78--3418042999270868539", |
"LSM" : { |
"bloom filter false positives" : 0, |
"bloom filter hits" : 0, |
"bloom filter misses" : 0, |
"bloom filter pages evicted from cache" : 0, |
"bloom filter pages read into cache" : 0, |
"bloom filters in the LSM tree" : 0, |
"chunks in the LSM tree" : 0, |
"highest merge generation in the LSM tree" : 0, |
"queries that could have benefited from a Bloom filter that did not exist" : 0, |
"sleep for LSM checkpoint throttle" : 0, |
"sleep for LSM merge throttle" : 0, |
"total size of bloom filters" : 0 |
},
|
"block-manager" : { |
"allocations requiring file extension" : 0, |
"blocks allocated" : 0, |
"blocks freed" : 0, |
"checkpoint size" : 29916192768, |
"file allocation unit size" : 4096, |
"file bytes available for reuse" : 8498855936, |
"file magic number" : 120897, |
"file major version number" : 1, |
"file size in bytes" : 107902332928, |
"minor version number" : 0 |
},
|
"btree" : { |
"btree checkpoint generation" : 0, |
"column-store fixed-size leaf pages" : 0, |
"column-store internal pages" : 0, |
"column-store variable-size RLE encoded values" : 0, |
"column-store variable-size deleted values" : 0, |
"column-store variable-size leaf pages" : 0, |
"fixed-record size" : 0, |
"maximum internal page key size" : 368, |
"maximum internal page size" : 4096, |
"maximum leaf page key size" : 2867, |
"maximum leaf page size" : 32768, |
"maximum leaf page value size" : 67108864, |
"maximum tree depth" : 0, |
"number of key/value pairs" : 0, |
"overflow pages" : 0, |
"pages rewritten by compaction" : 0, |
"row-store internal pages" : 0, |
"row-store leaf pages" : 0 |
},
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"cache" : { |
"bytes currently in the cache" : 213732, |
"bytes read into cache" : 176748, |
"bytes written from cache" : 0, |
"checkpoint blocked page eviction" : 0, |
"data source pages selected for eviction unable to be evicted" : 0, |
"hazard pointer blocked page eviction" : 0, |
"in-memory page passed criteria to be split" : 0, |
"in-memory page splits" : 0, |
"internal pages evicted" : 0, |
"internal pages split during eviction" : 0, |
"leaf pages split during eviction" : 0, |
"modified pages evicted" : 0, |
"overflow pages read into cache" : 0, |
"overflow values cached in memory" : 0, |
"page split during eviction deepened the tree" : 0, |
"page written requiring lookaside records" : 0, |
"pages read into cache" : 4, |
"pages read into cache requiring lookaside entries" : 0, |
"pages requested from the cache" : 3, |
"pages written from cache" : 0, |
"pages written requiring in-memory restoration" : 0, |
"tracked dirty bytes in the cache" : 0, |
"unmodified pages evicted" : 0 |
},
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"cache_walk" : { |
"Average difference between current eviction generation when the page was last considered" : 0, |
"Average on-disk page image size seen" : 0, |
"Clean pages currently in cache" : 0, |
"Current eviction generation" : 0, |
"Dirty pages currently in cache" : 0, |
"Entries in the root page" : 0, |
"Internal pages currently in cache" : 0, |
"Leaf pages currently in cache" : 0, |
"Maximum difference between current eviction generation when the page was last considered" : 0, |
"Maximum page size seen" : 0, |
"Minimum on-disk page image size seen" : 0, |
"On-disk page image sizes smaller than a single allocation unit" : 0, |
"Pages created in memory and never written" : 0, |
"Pages currently queued for eviction" : 0, |
"Pages that could not be queued for eviction" : 0, |
"Refs skipped during cache traversal" : 0, |
"Size of the root page" : 0, |
"Total number of pages currently in cache" : 0 |
},
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"compression" : { |
"compressed pages read" : 0, |
"compressed pages written" : 0, |
"page written failed to compress" : 0, |
"page written was too small to compress" : 0, |
"raw compression call failed, additional data available" : 0, |
"raw compression call failed, no additional data available" : 0, |
"raw compression call succeeded" : 0 |
},
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"cursor" : { |
"bulk-loaded cursor-insert calls" : 0, |
"create calls" : 1, |
"cursor-insert key and value bytes inserted" : 0, |
"cursor-remove key bytes removed" : 0, |
"cursor-update value bytes updated" : 0, |
"insert calls" : 0, |
"next calls" : 0, |
"prev calls" : 1, |
"remove calls" : 0, |
"reset calls" : 1, |
"restarted searches" : 0, |
"search calls" : 0, |
"search near calls" : 0, |
"truncate calls" : 0, |
"update calls" : 0 |
},
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"reconciliation" : { |
"dictionary matches" : 0, |
"fast-path pages deleted" : 0, |
"internal page key bytes discarded using suffix compression" : 0, |
"internal page multi-block writes" : 0, |
"internal-page overflow keys" : 0, |
"leaf page key bytes discarded using prefix compression" : 0, |
"leaf page multi-block writes" : 0, |
"leaf-page overflow keys" : 0, |
"maximum blocks required for a page" : 0, |
"overflow values written" : 0, |
"page checksum matches" : 0, |
"page reconciliation calls" : 0, |
"page reconciliation calls for eviction" : 0, |
"pages deleted" : 0 |
},
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"session" : { |
"object compaction" : 0, |
"open cursor count" : 1 |
},
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"transaction" : { |
"update conflicts" : 0 |
}
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}
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Â
It's very strange that the compaction cannot proceed because there is less 10%(10.7GB) free space in the first 90% physical space, there is only one internal checkpoint exists in WT, so why compaction cannot work with at least 60% free space.  ("size" : 29477552228, , "storageSize" : 107902332928)
Another node in this replica set reached the 10% threshold and compact successfully, the phsical space after compaction is 37GB (far more less then 107GB).
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2018-07-06T13:01:53.316+0800 I REPL [ReplicationExecutor] going into maintenance mode with 0 other maintenance mode tasks in progress 2018-07-06T13:01:53.316+0800 I REPL [ReplicationExecutor] transition to RECOVERING 2018-07-06T13:01:53.316+0800 I COMMAND [conn4] compact dbdoc.somecoll begin, options: paddingMode: NONE validateDocuments: 1 2018-07-06T13:01:53.367+0800 I ACCESS [conn12] Successfully authenticated as principal __cloud_internal on admin 2018-07-06T13:01:53.375+0800 I STORAGE [conn4] WiredTiger [1530853313:375677][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: ============ testing for compaction 2018-07-06T13:01:53.375+0800 I STORAGE [conn4] WiredTiger [1530853313:375742][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: file size 102903MB (107902332928) with 7% space available 8105MB (8498855936) 2018-07-06T13:01:53.467+0800 I NETWORK [conn12] end connection 127.0.0.1:44591 (6 connections now open) 2018-07-06T13:01:53.467+0800 I NETWORK [conn11] end connection 127.0.0.1:44582 (6 connections now open) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764520][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 0%: 3MB, (3489792B, 0%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764587][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 10%: 2204MB, (2311172096B, 27%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764603][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 20%: 1580MB, (1657495552B, 19%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764615][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 30%: 1539MB, (1614770176B, 18%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764627][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 40%: 692MB, (726429696B, 8%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764665][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 50%: 824MB, (864960512B, 10%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764678][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 60%: 444MB, (465973248B, 5%) 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764690][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 70%: 12MB, (12582912B, 0%)2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764702][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 80%: 9MB, (10027008B, 0%) |
2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764714][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: 90%: 793MB, (831954944B, 9%) |
265911 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764775][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: dbdoc/collection-78--3418042999270868539.wt: 7302MB (7656873984) available space in the first 80% of the file |
2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764796][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: dbdoc/collection-78--3418042999270868539.wt: 7311MB (7666900992) available space in the first 90% of the file |
2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764808][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: dbdoc/collection-78--3418042999270868539.wt: require 10% or 10290MB (10790233292) in the first 90% of the file to perform compaction , compaction skipped |
2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764825][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: ============ ending compaction pass |
2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764837][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: pages reviewed: 0 |
265916 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764850][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: pages skipped: 0 |
265917 2018-07-06T13:01:53.764+0800 I STORAGE [conn4] WiredTiger [1530853313:764861][21031:0x7effc9e7c700], file:dbdoc/collection-78--3418042999270868539.wt, WT_SESSION.compact: pages written: 0 |