5.0 zstd compression level is not working as expected

Ops and Admin
8

Hi @Aayushi_Mangal,

Thanks for link reference and detailing the test information you performed :slight_smile:

I had inserted about 500K test documents into a MongoDB version 4.2.21 instance with default compression and then mongorestore the dump of this same data to several test instances with varying compressions:

  • MongoDB version 5.0.10 zstd compression level 22
  • MongoDB version 5.0.10 zstd compression level 10
  • MongoDB version 5.0.10 default compression

The results are here below (for all the below tests please take note of the decreasing storageSize values):

MongoDB version 4.2.21, default compression:

  ns: 'compressdb.compresscoll',
  size: 767500000,
  count: 500000,
  avgObjSize: 1535,
  storageSize: 64327680

MongoDB version 5.0.10 default compression:

  ns: 'compressdb.compresscoll',
  size: 767500000,
  count: 500000,
  avgObjSize: 1535,
  storageSize: 54767616

MongoDB version 5.0.10 zstd compression, level 10:

  ns: 'compressdb.compresscoll',
  size: 767500000,
  count: 500000,
  avgObjSize: 1535,
  storageSize: 27152384

MongoDB version 5.0.10 zstd compression, level 22:

  ns: 'compressdb.compresscoll',
  size: 767500000,
  count: 500000,
  avgObjSize: 1535,
  storageSize: 1257472

For case 2 in your reply within this post:

  1. we inserted bulk fresh dummy data in all these mongo, but found no difference in compresion.

Could you run a db.collection.stats() on each of your test cases / instances and advise the following values for each test instance:

  • storageSize
  • creationString

Regards,
Jason

2 Likes