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https://issues.apache.org/jira/browse/CALCITE-5581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17704586#comment-17704586
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Vaibhav Joshi commented on CALCITE-5581:
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[~stoty]
This is Interesting.
I think if we implement retry logic ( retrying different host), "failed host
scenarios" are already taken care off.
Following are my thoughts.
* {*}Round Robin LB Strategy{*}: We treat lbURLs as a circular list. When
connection fails, we pick up the next host in the list. Failed host will be
attempted after N attempts. So technically we are getting the effect which you
suggested above.
* {*}Random Select{*}: Probability of recalling same host is very less due to
randomization. So even if we don't implement the host blacklisting logic, we
pick up a different host in 2nd or 3rd attempt (max).
So retry mechanism should be sufficient in first cut implementation.
High level we can have following. Behavior
# Define two parameters named *LB_FAILOVER_CONNECTION_TIMEOUT* and
*LB_FAILOVER_RETRIES*
# Try to create HTTP connection with the *LB_FAILOVER_CONNECTION_TIMEOUT* as
timeout parameter.
# When connection is failed, get a new URL using LBStrategy and retry that URL.
# Repeat #1 to #3 till {*}LB_FAILOVER_RETRIES.{*}{*}{*}
We can anyway have contribution in future and enhance this behavior in case we
have specific observations in the field.
> Implement Basic client side load balancing in Avatica Driver
> ------------------------------------------------------------
>
> Key: CALCITE-5581
> URL: https://issues.apache.org/jira/browse/CALCITE-5581
> Project: Calcite
> Issue Type: New Feature
> Components: avatica
> Affects Versions: 1.33.0
> Reporter: Vaibhav Joshi
> Assignee: Vaibhav Joshi
> Priority: Major
> Labels: pull-request-available
> Attachments: Avatica Basic client side load balancing.docx
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> Implement mechanism to support Client side load balancing by configuring
> connection properties for load balancing
> {code:java}
> jdbc:phoenix:thin:
> url=https://<host>:<port>;
> serialization=PROTOBUF;
> authentication=BASIC;
> avatica_user=<userName>;
> avatica_password=<userPw>
> useClientSideLB: [true/false]
> lbStrategy: [RandomDistribution/Sequential/RoundRobin]
> lbURLs: <comma separated URls e.g. URL1, URL2,URL3,...URLn> {code}
> Client should connect to any of the URLs specified in lbURLs ( depending on
> LB strategy selected). Please refer to [^Avatica Basic client side load
> balancing.docx]for more details
>
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