Convert Collection to Capped in MongoDB

MongoDBDatabaseBig Data Analytics

To convert collection to capped, use runCommand(). It provides a helper to run specified database commands. Let us first create a collection with documents −

> db.demo416.insertOne({"StudentName":"David"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e723a7bb912067e57771adf")
}
> db.demo416.insertOne({"StudentName":"Mike"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e723a81b912067e57771ae0")
}
> db.demo416.insertOne({"StudentName":"Sam"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e723a84b912067e57771ae1")
}

Display all documents from a collection with the help of find() method −

> db.demo416.find();

This will produce the following output −

{ "_id" : ObjectId("5e723a7bb912067e57771adf"), "StudentName" : "David" }
{ "_id" : ObjectId("5e723a81b912067e57771ae0"), "StudentName" : "Mike" }
{ "_id" : ObjectId("5e723a84b912067e57771ae1"), "StudentName" : "Sam" }

Following is the query to convert Collection to Capped −

> db.runCommand( { convertToCapped: 'demo416', size: 100} );
{ "ok" : 1 }

Following is the query to show details −

> db.demo416.stats();

This will produce the following output −

{
   "ns" : "test.demo416",
   "size" : 132,
   "count" : 3,
   "avgObjSize" : 44,
   "storageSize" : 16384,
   "capped" : true,
   "max" : -1,
   "maxSize" : 256,
   "sleepCount" : 0,
   "sleepMS" : 0,
   "wiredTiger" : {
      "metadata" : {
      "formatVersion" : 1
      },
      "creationString" : "access_pattern_hint=none,allocation_size=4KB,app_metadata=(formatVersion=1),assert=(commit_timestamp=format=btree,huffman_key=,huffman_value=,ignore_in_memory_cache_size=false,immutable=false,internal_true),lsm=(auto_throttle=true,bloom=true,bloom_bit_count=16,bloom_config=,bloom_hash_count=8,bloom_oldest=cache_dirty_max=0,os_cache_max=0,prefix_compression=false,prefix_compression_min=4,source=,split_deepen_"type" : "file",
      "uri" : "statistics:table:collection-28-7449704163321214584",
      "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" : 3,
            "blocks allocated" : 3,
            "blocks freed" : 0,
            "checkpoint size" : 4096,
            "file allocation unit size" : 4096,
            "file bytes available for reuse" : 0,
            "file magic number" : 120897,
            "file major version number" : 1,
            "file size in bytes" : 16384,
            "minor version number" : 0
            },
            "btree" : {
               "btree checkpoint generation" : 427,
               "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
            },
            "cache" : {
               "bytes currently in the cache" : 535,
               "bytes dirty in the cache cumulative" : 0,
               "bytes read into cache" : 232,
               "bytes written from cache" : 232,
               "checkpoint blocked page eviction" : 0,
               "data source pages selected for eviction unable to be evicted" : 0,
               "eviction walk passes of a file" : 0,
               "eviction walk target pages histogram - 0-9" : 0,
               "eviction walk target pages histogram - 10-31" : 0,
               "eviction walk target pages histogram - 128 and higher" : 0,
               "eviction walk target pages histogram - 32-63" : 0,
               "eviction walk target pages histogram - 64-128" : 0,
               "eviction walks abandoned" : 0,
               "eviction walks gave up because they restarted their walk twice" : 0,
               "eviction walks gave up because they saw too many pages and found no candidates" : 0,
               "eviction walks gave up because they saw too many pages and found too few candidates" : 0,
               "eviction walks reached end of tree" : 0,
               "eviction walks started from root of tree" : 0,
               "eviction walks started from saved location in tree" : 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" : 2,
               "overflow pages read into cache" : 0,
               "page split during eviction deepened the tree" : 0,
               "page written requiring cache overflow records" : 0,
               "pages read into cache" : 2,
               "pages read into cache after truncate" : 1,
               "pages read into cache after truncate in prepare state" : 0,
               "pages read into cache requiring cache overflow entries" : 0,
               "pages requested from the cache" : 4,
               "pages seen by eviction walk" : 0,
               "pages written from cache" : 2,
               "pages written requiring in-memory restoration" : 0,
               "tracked dirty bytes in the cache" : 0,
               "unmodified pages evicted" : 0
            },
            "cache_walk" : {
               "Average difference between current eviction generation when the page was last considered" : "Average on-disk page image size seen" : 0,
               "Average time in cache for pages that have been visited by the eviction server" : 0,
               "Average time in cache for pages that have not been visited by the eviction server" : 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" "Maximum page size seen" : 0,
               "Minimum on-disk page image size seen" : 0,
               "Number of pages never visited by eviction server" : 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
            },
            "compression" : {
               "compressed pages read" : 0,
               "compressed pages written" : 0,
               "page written failed to compress" : 0,
               "page written was too small to compress" : 2,
               "raw compression call failed, additional data available" : 0,
               "raw compression call failed, no additional data available" : 0,
               "raw compression call succeeded" : 0
         },
         "cursor" : {
            "bulk-loaded cursor-insert calls" : 0,
            "close calls that result in cache" : 0,
            "create calls" : 2,
            "cursor operation restarted" : 0,
            "cursor-insert key and value bytes inserted" : 135,
            "cursor-remove key bytes removed" : 0,
            "cursor-update value bytes updated" : 0,
            "cursors reused from cache" : 0,
            "insert calls" : 3,
            "modify calls" : 0,
            "next calls" : 0,
            "prev calls" : 2,
            "remove calls" : 0,
            "reserve calls" : 0,
            "reset calls" : 7,
            "search calls" : 0,
            "search near calls" : 0,
            "truncate calls" : 0,
            "update calls" : 0
         },
         "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" : 2,
            "page reconciliation calls for eviction" : 2,
            "pages deleted" : 0
         },
         "session" : {
            "cached cursor count" : 1,
            "object compaction" : 0,
            "open cursor count" : 0
         },
         "transaction" : {
            "update conflicts" : 0
         }
      },
      "nindexes" : 1,
      "totalIndexSize" : 16384,
      "indexSizes" : {
         "_id_" : 16384
      },
   "ok" : 1
}
raja
Published on 03-Apr-2020 13:35:01
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