Overview
La mergeChunks El comando permite combinar fragmentos continuos en la misma partición en un solo fragmento. Este tutorial explica cómo fusionar fragmentos vecinos en un clúster shardado.
Procedimiento
Nota
Los ejemplos de este procedimiento utilizan una members colección en la test base de datos, utilizando el campo username como la Clave de partición.
Identificar rangos de fragmentos
En mongosh, identifica los rangos de fragmento con la siguiente operación:
sh.status()
En la salida, los rangos de fragmentos aparecen después de los recuentos de fragmentos para cada colección particionada, como en el siguiente ejemplo:
--- Sharding Status --- sharding version: { "_id" : 1, "minCompatibleVersion" : 5, "currentVersion" : 6, "clusterId" : ObjectId("5ebf0bfd3eeb6037ec7cbba9") } shards: { "_id" : "shardA", "host" : "shardA/shardA-m1.example.net:27018,shardA-m2.example.net:27018,shardA-m3.example.net:27018", "state" : 1 } { "_id" : "shardB", "host" : "shardB/shardB-m1.example.net:27018,shardB-m2.example.net:27018,shardB-m3.example.net:27018", "state" : 1 } active mongoses: "4.4.0" : 1 autosplit: Currently enabled: yes balancer: Currently enabled: yes Currently running: no Failed balancer rounds in last 5 attempts: 0 Migration Results for the last 24 hours: 519 : Success databases: { "_id" : "config", "primary" : "config" } config.system.sessions shard key: { "_id" : 1 } unique: false balancing: true chunks: shardA 512 shardB 512 too many chunks to print, use verbose if you want to force print { "_id" : "test", "primary" : "shardA", "version" : { "uuid" : UUID("22c042fc-7e3d-4c6d-992d-f3d714759781"), "lastMod" : 1 } } test.members shard key: { "username" : 1 } unique: false balancing: true chunks: shardA 7 shardB 7 { "username" : { "$minKey" : 1 } } -->> { "username" : "user16643" } on : shardB Timestamp(13, 0) { "username" : "user16643" } -->> { "username" : "user2329" } on : shardB Timestamp(16, 0) { "username" : "user2329" } -->> { "username" : "user29937" } on : shardB Timestamp(17, 0) { "username" : "user29937" } -->> { "username" : "user36583" } on : shardB Timestamp(18, 0) { "username" : "user36583" } -->> { "username" : "user43229" } on : shardB Timestamp(19, 0) { "username" : "user43229" } -->> { "username" : "user49877" } on : shardB Timestamp(20, 0) { "username" : "user49877" } -->> { "username" : "user56522" } on : shardB Timestamp(21, 0) { "username" : "user56522" } -->> { "username" : "user63169" } on : shardA Timestamp(21, 1) { "username" : "user63169" } -->> { "username" : "user69816" } on : shardA Timestamp(10, 1) { "username" : "user69816" } -->> { "username" : "user76462" } on : shardA Timestamp(11, 1) { "username" : "user76462" } -->> { "username" : "user83108" } on : shardA Timestamp(12, 1) { "username" : "user83108" } -->> { "username" : "user89756" } on : shardA Timestamp(14, 1) { "username" : "user89756" } -->> { "username" : "user96401" } on : shardA Timestamp(15, 1) { "username" : "user96401" } -->> { "username" : { "$maxKey" : 1 } } on : shardA Timestamp(15, 2)
Los rangos de fragmentos aparecen después de los conteos de fragmentos para cada colección particionada. Por ejemplo, los siguientes son los rangos de fragmentos para la colección test.members:
{ "username" : { "$minKey" : 1 } } -->> { "username" : "user16643" } on : shardB Timestamp(13, 0) { "username" : "user16643" } -->> { "username" : "user2329" } on : shardB Timestamp(16, 0) { "username" : "user2329" } -->> { "username" : "user29937" } on : shardB Timestamp(17, 0) { "username" : "user29937" } -->> { "username" : "user36583" } on : shardB Timestamp(18, 0) { "username" : "user36583" } -->> { "username" : "user43229" } on : shardB Timestamp(19, 0) { "username" : "user43229" } -->> { "username" : "user49877" } on : shardB Timestamp(20, 0) { "username" : "user49877" } -->> { "username" : "user56522" } on : shardB Timestamp(21, 0) { "username" : "user56522" } -->> { "username" : "user63169" } on : shardA Timestamp(21, 1) { "username" : "user63169" } -->> { "username" : "user69816" } on : shardA Timestamp(10, 1) { "username" : "user69816" } -->> { "username" : "user76462" } on : shardA Timestamp(11, 1) { "username" : "user76462" } -->> { "username" : "user83108" } on : shardA Timestamp(12, 1) { "username" : "user83108" } -->> { "username" : "user89756" } on : shardA Timestamp(14, 1) { "username" : "user89756" } -->> { "username" : "user96401" } on : shardA Timestamp(15, 1) { "username" : "user96401" } -->> { "username" : { "$maxKey" : 1 } } on : shardA Timestamp(15, 2)
Combinar fragmentos
Fusionar fragmentos contiguos en la misma partición.
Por ejemplo, considere los siguientes rangos de fragmentos en shardA:
Nota
Se resaltan los fragmentos que hay que combinar.
{ "username" : "user56522" } -->> { "username" : "user63169" } on : shardA Timestamp(21, 1) { "username" : "user63169" } -->> { "username" : "user69816" } on : shardA Timestamp(10, 1) { "username" : "user69816" } -->> { "username" : "user76462" } on : shardA Timestamp(11, 1) { "username" : "user76462" } -->> { "username" : "user83108" } on : shardA Timestamp(12, 1) { "username" : "user83108" } -->> { "username" : "user89756" } on : shardA Timestamp(14, 1) { "username" : "user89756" } -->> { "username" : "user96401" } on : shardA Timestamp(15, 1) { "username" : "user96401" } -->> { "username" : { "$maxKey" : 1 } } on : shardA Timestamp(15, 2)
Para fusionar los fragmentos contiguos resaltados, emita el comando mergeChunks contra la base de datos admin:
db.adminCommand( { mergeChunks: "test.members", bounds: [ { "username" : "user69816" }, { "username" : "user96401" } ] } )
En caso de éxito, mergeChunks produce la siguiente salida:
{ "ok" : 1, "operationTime" : Timestamp(1589580356, 14), "$clusterTime" : { "clusterTime" : Timestamp(1589580356, 14), "signature" : { "hash" : BinData(0,"up5VKd49G/uPCq1iger2nOtfIHw="), "keyId" : Long("6827188741371592725") } } }
En cualquier condición de fallo, mergeChunks devuelve un documento donde el valor del campo ok es 0.
Ver rangos de fragmentos combinados
Después de fusionar los fragmentos identificados, confirma el nuevo fragmento de la siguiente manera:
sh.status()
La salida de sh.status() debería asemejarse a:
--- Sharding Status --- sharding version: { "_id" : 1, "minCompatibleVersion" : 5, "currentVersion" : 6, "clusterId" : ObjectId("5ebef5447fa151d4bd79dd72") } shards: { "_id" : "shardA", "host" : "shardA/shardA-m1.example.net:27018,shardA-m2.example.net:27018,shardA-m3.example.net:27018", "state" : 1 } { "_id" : "shardB", "host" : "shardB/shardB-m1.example.net:27018,shardB-m2.example.net:27018,shardB-m3.example.net:27018", "state" : 1 } active mongoses: "4.4.0" : 1 autosplit: Currently enabled: yes balancer: Currently enabled: yes Currently running: no Failed balancer rounds in last 5 attempts: 0 Migration Results for the last 24 hours: 519 : Success databases: { "_id" : "config", "primary" : "config" } config.system.sessions shard key: { "_id" : 1 } unique: false balancing: true chunks: shardA 512 shardB 512 too many chunks to print, use verbose if you want to force print { "_id" : "test", "primary" : "shardA", "version" : { "uuid" : UUID("22c042fc-7e3d-4c6d-992d-f3d714759781"), "lastMod" : 1 } } test.members shard key: { "username" : 1 } unique: false balancing: true chunks: shardA 5 shardB 6 { "username" : { "$minKey" : 1 } } -->> { "username" : "user16643" } on : shardA Timestamp(22, 0) { "username" : "user16643" } -->> { "username" : "user2329" } on : shardB Timestamp(22, 1) { "username" : "user2329" } -->> { "username" : "user29937" } on : shardB Timestamp(17, 0) { "username" : "user29937" } -->> { "username" : "user36583" } on : shardB Timestamp(18, 0) { "username" : "user36583" } -->> { "username" : "user43229" } on : shardB Timestamp(19, 0) { "username" : "user43229" } -->> { "username" : "user49877" } on : shardB Timestamp(20, 0) { "username" : "user49877" } -->> { "username" : "user56522" } on : shardB Timestamp(21, 0) { "username" : "user56522" } -->> { "username" : "user63169" } on : shardA Timestamp(21, 1) { "username" : "user63169" } -->> { "username" : "user69816" } on : shardA Timestamp(10, 1) { "username" : "user69816" } -->> { "username" : "user96401" } on : shardA Timestamp(21, 2) { "username" : "user96401" } -->> { "username" : { "$maxKey" : 1 } } on : shardA Timestamp(15, 2)
Después de la fusión, el balanceador puede migrar fragmentos entre particiones para garantizar una distribución más uniforme de fragmentos.