replace with getField

[marevol]

Description

In FlatObjectFieldMapper#parseValueAddFields, getFields is called, but getField needs to be used.

Related Issues

Resolves #7835

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

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.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/16632/
• CommitID: a629384
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[reta]

Thanks for the change, @marevol , it would be great to have a test case that showcased this issue (and the fix), could you craft one please? Thank you.

[marevol]

Our test case is:

1. Preparing 20,000,000 documents containing flat_object data
2. Inserting the documents and measuring the indexing time
   (we compared it with the flattened type in Elasticsearch. The indexing time for the flattened type was 3 hours, but for flat_object, it was 12 hours...)
3. Checking the result from the Nodes hot threads API
   'getFields' appears to be time-consuming in the results.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/16635/
• CommitID: 562a8a0
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[reta]

Our test case is:

@marevol That's certainly a good one, do you see the way the issue could have been caught in unit / integration tests since it obviously does use wrong API? thank you.

[marevol]

We found this issue in performance tests.
The behavior of flat_object type looked okay.
So it might be difficult to find it in JUnit tests.

[reta]

Please add the entry to CHANGELOG file, under [Unreleased 2.x] / Fixed section

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/19216/
• CommitID: dea6dbf
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[noCharger]

org.opensearch.painless.LangPainlessClientYamlTestSuiteIT > test {yaml=painless/30_search/Flat-object fields from within the scripting} FAILED
    java.lang.AssertionError: Failure at [painless/30_search:559]: field [hits.hits] doesn't have length [1]
    Expected: <1>
         but: was <0>
        at __randomizedtesting.SeedInfo.seed([DACE9185F5EE8DF:85F8D6C2F1A28527]:0)
        at org.opensearch.test.rest.yaml.OpenSearchClientYamlSuiteTestCase.executeSection(OpenSearchClientYamlSuiteTestCase.java:460)
        at org.opensearch.test.rest.yaml.OpenSearchClientYamlSuiteTestCase.test(OpenSearchClientYamlSuiteTestCase.java:433)
        at java.****/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.****/java.lang.reflect.Method.invoke(Method.java:578)
        at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1750)
        at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:938)
        at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:974)
        at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:988)
        at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)

75bb3ef
https://github.com/opensearch-project/OpenSearch/blame/bcaf49455fc6dacd1e19e32b8457a8bc33991c7a/modules/lang-painless/src/yamlRestTest/resources/rest-api-spec/test/painless/30_search.yml#L488

[mingshl]

@marevol we can remove this painless from L488 test. It should help you with the gradle ceck.

I remembered @lukas-vlcek was nice to add in this painless test. But since we agree on FlatObject currently do not support painless script, and we have a new issue here assigned to lukas for future development , so it's fine to remove this test .

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/19338/
• CommitID: 5b16cbc
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/19489/
• CommitID: b2a05b1
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationRemoteStoreIT.testRestartPrimary

• URL: https://build.ci.opensearch.org/job/gradle-check/19491/
• CommitID: 3634bd3
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[mingshl]

@reta can we get reviews again? Trying to see if we can make this in for. 2. 9?

[reta]

@mingshl sign off from you before merge? thank you

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

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-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-7855-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 828730f23377e78dd1df0fa53939ed7f2486800e
# Push it to GitHub
git push --set-upstream origin backport/backport-7855-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-7855-to-2.x.

[reta]

@mingshl mind please backporting manually ? thank you