[SERVER-16970] WiredTiger index prefix compression configuration is not applied to creationString Created: 21/Jan/15  Updated: 23/Jan/15  Resolved: 21/Jan/15

Status: Closed
Project: Core Server
Component/s: WiredTiger
Affects Version/s: 2.8.0-rc5
Fix Version/s: 3.0.0-rc6

Type: Bug Priority: Major - P3
Reporter: Kyle Erf Assignee: Eric Milkie
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Operating System: ALL
Participants:

 Description   

On server commit 876f5f475bf9242c098e6de641aa7ee0982803c2

Using the yaml config option

{
    storage: {
        engine: wiredTiger,
        wiredTiger: {
            indexConfig: {
                prefixCompression: true
            },
        },
    },
}

does not affect the creationString of new indexes. Created indexes have the default options:

"allocation_size=4KB,app_metadata=(formatVersion=6,infoObj={ \"v\" : 1, \"key\" : { \"a\" : 1 }, \"name\" : \"a_1\", \"ns\" : \"test.z\" }),block_allocation=best,block_compressor=,cache_resident=0,checkpoint=(WiredTigerCheckpoint.1=(addr=\"018181e4562b79468281e4f2e09da0808080808080e21fc0dfc0\",order=1,time=1421864784,size=8192,write_gen=2)),checkpoint_lsn=(4,4736),checksum=uncompressed,collator=,columns=,dictionary=0,format=btree,huffman_key=,huffman_value=,id=3,internal_item_max=0,internal_key_max=0,internal_key_truncate=,internal_page_max=4KB,key_format=u,key_gap=10,leaf_item_max=0,leaf_key_max=0,leaf_page_max=16k,leaf_value_max=0,memory_page_max=5MB,os_cache_dirty_max=0,os_cache_max=0,prefix_compression=,prefix_compression_min=4,split_pct=75,value_format=u,version=(major=1,minor=1)"

and do not show statistical evidence that prefix compression is actually happening. In the creation string, we should be seeing prefix_compression=true



 Comments   
Comment by Githook User [ 21/Jan/15 ]

Author:

{u'username': u'milkie', u'name': u'Eric Milkie', u'email': u'milkie@10gen.com'}

Message: SERVER-16970 set prefix_compression explicitly to true
Branch: master
https://github.com/mongodb/mongo/commit/e339dbf6fcee2d64b47c4d4eadf7d8c597f48f82

Comment by Eric Milkie [ 21/Jan/15 ]

"prefix_compression=" is in there but it has no value. I incorrectly assumed that it would default to "on" if an option was present with no value.

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