BrodaUa opened a new issue #267:
URL: https://github.com/apache/couchdb-nano/issues/267
<!--- Provide a general summary of the issue in the Title above -->
Hello. I have a question regarding Nano performance:
Is it possible to use Reading Changes Feed (aka nano.changesReader) to track
the changes in parallel for a large number (1k...10k) of databases in a single
CouchDB instance? Currently I see the big performance slowdown, as it takes
minutes (10-20 min) to pick-up the latest change in any db. Thanks.
## Expected Behavior
<!--- If you're describing a bug, tell us what should happen -->
<!--- If you're suggesting a change/improvement, tell us how it should work
-->
No performance issues in case of 1k parallel changes feed listeners.
## Current Behavior
<!--- If describing a bug, tell us what happens instead of the expected
behavior -->
<!--- If suggesting a change/improvement, explain the difference from
current behavior -->
It takes minutes to pick-up the latest change in any db
## Steps to Reproduce (for bugs)
<!--- Provide a link to a live example, or an unambiguous set of steps to -->
<!--- reproduce this bug. Include code to reproduce, if relevant -->
1. create 1k dbs
2. create 1k EventEmitter's via
```
nano.use(dbName).changesReader
.start({ includeDocs: true })
.on("change", changes => {
console.log(`change in ${dbName}: `, changes);
})
.on('error', (error) => {
console.log(` error in ${dbName}`, error);
});
```
## Context
<!--- How has this issue affected you? What are you trying to accomplish? -->
<!--- Providing context helps us come up with a solution that is most useful
in the real world -->
Related use-case - messaging app. Each user has a message db, with outgoing
and incoming messages. I want to track the changes when I send a message to
somebody (here the message stored in db via PouchDB - CouchDB sync process),
lookup the destination and write this message in destination user db.
## Your Environment
<!--- Include as many relevant details about the environment you experienced
the bug in -->
* Version used: couchdb:3.1; "nano": "^9.0.3"
* Operating System and version (desktop or mobile): ubuntu 18.04
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