[GitHub] wohali commented on issue #1422: GET/ {db} request returns the structured response but instance_start_time has value "0"

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wohali commented on issue #1422: GET/ {db} request returns the structured response but instance_start_time has value "0"
URL: https://github.com/apache/couchdb/issues/1422#issuecomment-402403200
 
 
   This is a documentation error, and relates to clustering.
   
   TL;DR: We don't recommend you rely on this value for anything in CouchDB 2.x or later versions. If you need to store when a database is created, create a document inside the database that includes that information at the time you create a database yourself.
   
   The reason this information is not available on the clustered interface is that, for a default CouchDB cluster setup of 3 nodes with q=8, there are 24 database shards for any given database, each of which has its own instance_start_time.
   
   There is currently no way to get each shard's instance start time through the clustered interface. However, on each node via localhost through the node-local (port 5986), you can get the instance_start_time per shard:
   
   ```
    $ curl http://localhost:5986/shards%2F00000000-1fffffff%2Fabc.1530133574
   {"db_name":"shards/00000000-1fffffff/abc.1530133574","engine":"couch_bt_engine","doc_count":127,"doc_del_count":0,"update_seq":127,"purge_seq":0,"compact_running":false,"sizes":{"active":31925,"external":3544,"file":90308},"disk_size":90308,"data_size":31925,"other":{"data_size":3544},"instance_start_time":"1530692235563311","disk_format_version":6,"committed_update_seq":127,"compacted_seq":127,"uuid":"953768671309b22f6bf8a5eae62f94a4"}
   ```
   
   Note again that this value will be different across multiple shards in the same database, as well as across multiple nodes in the same cluster. Only for a q=1 database in a single standalone server will you have a single instance_start_time value, which can and will change after database compaction (which occurs automatically by default.)
   
   **DO NOT USE PORT 5986 FOR REGULAR DATABASE OPERATIONS**. This interface is deprecated in 2.x and will be removed entirely in 3.x. By that time there will be replacements for all potential needs on the clustered interface.

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