*Answer from Copilot:*
Ah, the intricate dance of Solr shards and their cosmic collisions! Let’s
unravel this like a digital detective, shall we? 🕵️♂️
When it comes to Solr and its distributed architecture, handling duplicate
documents across shards can be as tricky as juggling flaming torches while
riding a unicycle. But fear not—I’ve got some insights for you:
1.
*Duplicate Documents and Shards:*
- Imagine our document—a digital doppelgänger—migrating from one shard
to another. It’s like a restless soul seeking a new home.
- During this transition, both shards might harbor copies of the same
document. They’re like twins separated at birth, each vying for the
spotlight.
2.
*The Solr Query Showdown:*
- Now, let’s stage a Solr query duel. Our query gallops across the
shards, demanding answers.
- If our document is the top-ranked contender in both shards, who
emerges victorious? 🏆
3.
*The Winner Takes It All (Sort of):*
- Solr, being the wise oracle it is, follows a simple rule: *“First
come, first served.”*
- When Solr discovers duplicate document IDs during distributed
searching, it selects the *first document* it encounters and discards
subsequent ones. It’s like a cosmic game of “finders keepers.”
- So, whichever shard’s copy of the document was indexed first—the
early bird with the freshest ink—takes the spotlight. The other copy bows
out gracefully.
4.
*The Momentary Sync Shimmy:*
- But wait! There’s a twist. If a commit happens between the first and
second phase of the distributed search, the index might shimmy
out of sync
for a moment.
- Picture this: Shard A says, “I’ve got the document!” Shard B says,
“No, I’ve got it!” And Solr, in its infinite wisdom, says, “Hold
my query,
folks—I need to sync up.”
- Eventually, harmony is restored, and the universe aligns itself.
But for that brief moment, Solr juggles realities like a cosmic circus
performer.
5.
*The Shard Key Sorcery:*
- Remember the shard key? It’s like Solr’s secret handshake. You can use
it to influence how documents are distributed across shards.
- For example, if you want to spread documents related to a specific
customer (let’s say “IBM”) across multiple shards, you can use a syntax
like this: "shard_key/num!document_id". The /num part determines how
many bits from the shard key contribute to the composite hash
<https://solr.apache.org/guide/solr/latest/deployment-guide/solrcloud-shards-indexing.html>
1
<https://solr.apache.org/guide/solr/latest/deployment-guide/solrcloud-shards-indexing.html>
.
6.
*Balance and Scalability:*
- To prevent hotspots, distribute documents evenly across shards.
Balance is key!
- Choose shard keys that reflect your data’s access patterns. Think
of them as Solr’s cosmic compass.
- And maintain flexibility—consider using composite IDs for easier
scalability. It’s like Solr’s way of saying, “Why settle for one
shard when
you can have a whole constellation?”
So, in the grand Solr arena, the early bird document wins the query race.
But remember, even in the digital cosmos, duplicates play by the
rules—mostly.
Deepak
"The greatness of a nation can be judged by the way its animals are treated
- Mahatma Gandhi"
+91 73500 12833
deic...@gmail.com
LinkedIn: www.linkedin.com/in/deicool
"Plant a Tree, Go Green"
Make In India : http://www.makeinindia.com/home
On Mon, Jul 29, 2024 at 10:11 PM Saksham Gupta
<saksham.gu...@indiamart.com.invalid> wrote:
> Hi Solr Developers,
>
> Which solr document will be displayed if a duplicate instance of the same
> document is present?
>
> In our current solr architecture, there is a possibility that a document
> can move from one solr shard to another shard. While the document will
> eventually be deleted from its old shard, there will be some duration where
> multiple instances of this document will be present.
>
> Now, if a solr query executes on both these shards and this document is the
> top ranked document from both the shards, which document will be returned
> in solr result?
>
