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

trying to compare the compression rate of mongoDB but, the results are not as expected. Here are my experiments.
 /etc/mongod.conf

1. mongod.conf //default setting

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

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

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

1. network interfaces
   net:
   port: 27017
   bindIp: 127.0.0.1

1. how the process runs
   processManagement:
   timeZoneInfo: /usr/share/zoneinfo

#security:
#operationProfiling:
#replication:
#sharding:

1. 1. Enterprise-Only Options:
      #auditLog:
      #snmp:
       

      Setting compression when creating collection in mongoDB shell

      mongoDB shell> db.createCollection( "test",{storageEngine:{wiredTiger:

      Unknown macro: {configString}

      }})

      The compression options are set to 6 in total

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

      When checked with db.printCollectionStats(), the options were applied correctly.

      insert data size is 100KB * 100000 = about 9GB.

but db.test.storageSize() result.

block_compression none = 10653536256 (byte)

block_compression snappy = 10653405184 (byte)

block_compression zlib = 6690177024 (byte)

zlib is about 40% compressed compared to none. but, none and snappy are not different.

(prefix_compress is also unchanged.)

What settings should I add?

+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
}
 

what is "page written failed to compress" mean? What is the solution?

+update2

used mongoDB server version: 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 } )
 

collection stats is too long so I will put only two.

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,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_custom=(prefix=,start_generation=0,suffix=),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=false,prefix_compression_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,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_custom=(prefix=,start_generation=0,suffix=),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_compression_min=4,source=,split_deepen_min_child=0,split_deepen_per_child=0,split_pct=90,type=file,value_format=u",

Thank you for your interest.