[SERVER-36820] Wired Tiger Compression Created: 23/Aug/18  Updated: 16/Nov/21  Resolved: 23/Aug/18

Status: Closed
Project: Core Server
Component/s: WiredTiger
Affects Version/s: 4.0.1
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Tanveer Madan Marate Assignee: Eric Milkie
Resolution: Duplicate Votes: 0
Labels: compression, wiredtiger
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Amazon Linux


Issue Links:
Related
is related to WT-3897 raw compression (lz4, zlib) less effe... Closed
is related to WT-3968 Use compression ratio to tune page sizes Closed
Operating System: ALL
Participants:
Case:

 Description   

Hi,

We recently upgraded out MongoDB from community version 3.4.14 to 4.0.1

We see that the compression ratio differs for the same type of data between the version

Hence we did a test and found that compression ratio drastically fell for 3.6+ 

Version Raw size Storage size Comp Ratio
4.0 10378066324 1594658816 6.5x
3.6 10378066324 1599205376 6.49x
3.4 10378066324 634499072 16.35x

Can you please suggest if any changes has to be made in the configuration of MongoDB or WiredTiger?

Below is the wired tiger configuration we are using

wiredTiger:
collectionConfig:
blockCompressor: zlib
engineConfig:
directoryForIndexes: true
journalCompressor: none
cacheSizeGB: 40
configString: "eviction_dirty_target=60, eviction_dirty_trigger=80, eviction=(threads_min=20,threads_max=20)"

Thanks,

Tanveer

 



 Comments   
Comment by Tanveer Madan Marate [ 23/Aug/18 ]

Thanks Eric !!!

Comment by Eric Milkie [ 23/Aug/18 ]

Version 4.0.2 is still unreleased, but it will be released in the coming months; watch for an announcement on the mongodb-announce google group. The fix is also proposed for backport into the 3.6 branch.

Comment by Tanveer Madan Marate [ 23/Aug/18 ]

Hi Eric,

Thanks for sharing the information !!!!

I see that currently 4.0.1 is marked as the Current Stable Release on https://www.mongodb.com/download-center#community

Can you share the link with me where to get 4.0.2 binaries?

Thanks,

Tanveer 

Comment by Eric Milkie [ 23/Aug/18 ]

Thank you for your report. I believe we have fixed the compression ratio issue you are experiencing.
Please see the linked tickets for more info; in particular, in WT-3968 we improved compression for zlib in version 4.0.2.

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