Question

Nginx + php-fpm + mongoDB（+ mongodb php-lib）

试图比较mongoDB的压缩率但是结果却不如预期。这是我的实验。

/etc/mongod.conf  

# mongod.conf  //default setting

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# Where and how to store data.
storage:
  dbPath: /var/lib/mongodb
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1

# how the process runs
processManagement:
  timeZoneInfo: /usr/share/zoneinfo

#security:
#operationProfiling:
#replication:
#sharding:
## Enterprise-Only Options:
#auditLog:
#snmp:

在mongoDB shell中创建集合时设置压缩

mongoDB shell> db.createCollection（“ test”，{storageEngine：{wiredTiger：{configString：'block_compressor = none，prefix_compression = false'}}}）

压缩选项总共设置为6

block_compressor = none或snappy或zlib // prefix_compression = false或true

与db.printCollectionStats（）一起检查时，选项已正确应用。

插入数据大小为100KB * 100000 =约9GB。

但是db.test.storageSize（）结果。

block_compression none = 10653536256（字节）

block_compression snappy = 10653405184（字节）

block_compression zlib = 6690177024（字节）

与没有压缩相比，zlib压缩了大约40％。但是，没有一个和活泼的一样。

（prefix_compress也保持不变。）

我应该添加什么设置？

+ UPDATE

snappy + false

"compression" : {
            "compressed pages read" : 0,
            "compressed pages written" : 0,
            "page written failed to compress" : 100007,
            "page written was too small to compress" : 1025
       }

zlib + false

"compression" : {
            "compressed pages read" : 0,
            "compressed pages written" : 98881,
            "page written failed to compress" : 0,
            "page written was too small to compress" : 924
       }

“写入的页面无法压缩”是什么意思？解决办法是什么？

+ update2

使用的mongoDB服务器版本：4.0.9

insert data document

$result = $collection->insertOne( ['num'=> (int)$i , 
                                    'title' => "$i", 
                                    'main' => "$i", 
                                    'img' => "$t",
                                    'user'=>"$users", 
                                    'like'=> 0,
                                    'time'=> "$date" ] );

---Variable Description---
$i = 1 ~ 100,000 (Increment by 1)
$t = 100KB(102400byt) random string 
$users =  (Random 10 characters in 12134567890abcdefghij)
$data =  Real-time server date (ex = 2019:05:18 xx.xx.xx)

index 
db.test.createIndex( { "num":1 } )
db.test.createIndex( { "title":1 } )
db.test.createIndex( { "user":1 } )
db.test.createIndex( { "like":1 } )
db.test.createIndex( { "time":1 } )

收集统计信息太长，因此我只输入两个。

snappy + false

“ creationString”：“ access_pattern_hint = none，allocation_size = 4KB，app_metadata =（formatVersion = 1），assert =（commit_timestamp = none，read_timestamp = none），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，不可变= 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， 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_custom =（前缀=，开始生成= 0，后缀=），merge_max = 15，merge_min = 0），memory_page_image_max = 0，memory_page_max = 10m，os_cache_dirty_max = 0，os_cache_max = 0，前缀压缩= false ，prefix_compr ession_min = 4，source =，split_deepen_min_child = 0，split_deepen_per_child = 0，split_pct = 90，type = file，value_format = u“，

snappy + true

“ creationString”：“ access_pattern_hint = none，allocation_size = 4KB，app_metadata =（formatVersion = 1），assert =（commit_timestamp = none，read_timestamp = none），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，不可变= 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， 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_custom =（前缀=，开始生成= 0，后缀=），merge_max = 15，merge_min = 0），memory_page_image_max = 0，memory_page_max = 10m，os_cache_dirty_max = 0，os_cache_max = 0， prefix_compression = true ，prefix_compre ssion_min = 4，source =，split_deepen_min_child = 0，split_deepen_per_child = 0，split_pct = 90，type = file，value_format = u“，

感谢您的关注。

Answer 1

跳出来的一件事是您使用allocation_size=4KB。使用此分配大小，您的磁盘块太小而无法压缩，因此它们不会被压缩。增加allocation_size即可开始压缩。

似乎mongoDB压缩无法正常工作

1 个答案: