Update default to 0 to always build graph as default behavior

[VijayanB]

Description

Update default to 0 to always build graph as default behavior

Conclusion

We performed following experiment to analyze the increase in latency (p90)
Data set: Cohere
Vector Count: 10M
Dimension: 768
Force merge to 1 segment: No
Concurrent Segment Enabled: yes
No of runs per limit: 5

Results

Comparison
P90 Metrics (ms) for Search

Metric	LIMIT = 0	LIMIT = 5K	LIMIT = 10K	LIMIT = 15K
MIN	21.56	22.8	25.4	27.1
MAX	22.5	23.4	26.2	28.1
AVG	21.56	22.94	25.6	27.78

Indexing

LIMIT	Total Indexing Time (secs)
0	2023
5K	1306
10K	1210
15K	1016

In order to avoid any regression from vector search, we are falling back to 0 as limit. However, users can configure this if they want to improve indexing performance by considering how that will impact the search latency.

The drop in latency is due to exact search was preferred over Approx search for segments where limit is not met.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[VijayanB]

We performed following experiment to analyze the drop in latency (p90)
Data set: Cohere
Vector Count: 10M
Dimension: 768
Force merge to 1 segment: No
Concurrent Segment Enabled: yes
No of runs per limit: 5

Results

Comparison
P90 Metrics

Metric	LIMIT = 0	LIMIT = 5K	LIMIT = 10K	LIMIT = 15K
MIN	21.56	22.8	25.4	27.1
MAX	22.5	23.4	26.2	28.1
AVG	21.56	22.94	25.6	27.78

In order to avoid any regression from approximate search, we are falling back to 0 as limit. However, users can configure this if they want to improve indexing performance by considering how that will impact the search latency.

The drop in latency is due to exact search was preferred over Approx search for segments where limit is not met.

[navneet1v]

We performed following experiment to analyze the drop in latency (p90) Data set: Cohere Vector Count: 10M Dimension: 768 Force merge to 1 segment: No Concurrent Segment Enabled: yes No of runs per limit: 5

Results

Comparison P90 Metrics

Metric LIMIT = 0 LIMIT = 5K LIMIT = 10K LIMIT = 15K
MIN 21.56 22.8 25.4 27.1
MAX 22.5 23.4 26.2 28.1
AVG 21.56 22.94 25.6 27.78
In order to avoid any regression from approximate search, we are falling back to 0 as limit. However, users can configure this if they want to improve indexing performance by considering how that will impact the search latency.

The drop in latency is due to exact search was preferred over Approx search for segments where limit is not met.

Thanks for the details. Please add the indexing time also for these runs.

[navneet1v]

@VijayanB please update the documentation too with details on how to set these numbers.

[navneet1v]

Indexing

LIMIT Total Indexing Time (ms)
0 2023
5K 1306
10K 1210
15K 1016

is this ms or sec?

[VijayanB]

Indexing
LIMIT Total Indexing Time (ms)
0 2023
5K 1306
10K 1210
15K 1016

is this ms or sec?
You are right. It is seconds. I fixed it. Thanks

[opensearch-trigger-bot]

The backport to main failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-main main
# Navigate to the new working tree
cd .worktrees/backport-main
# Create a new branch
git switch --create backport/backport-2452-to-main
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 388525617e7cb6740821c575650fdb7a55fbcc4b
# Push it to GitHub
git push --set-upstream origin backport/backport-2452-to-main
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-main

Then, create a pull request where the base branch is main and the compare/head branch is backport/backport-2452-to-main.