HIVE-29668: Add -rebuildIndexes utility to reconstruct backend Metast…

[soumyakanti3578]

…ore indexes

What changes were proposed in this pull request?

1. Add a rebuildIndexes option to schemaTool
2. For postgres, mysql, oracle, and mssql, add a rebuild-indexes sql file that drops and recreates all HMS indexes.
3. Tests

Why are the changes needed?

Gives users the ability to drop and recreate indexes easily through schematool.

Does this PR introduce any user-facing change?

Yes, adds a new option to schematool.

How was this patch tested?

mvn -pl standalone-metastore/metastore-server -Dtest=TestRebuildIndexesScriptConsistency  test
mvn -pl standalone-metastore/metastore-server -Dtest="TestSchemaToolForMetastore#testRebuildIndexes" -Dtest.groups="" -DfailIfNoTests=false test

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[nrg4878]

I wasnt expecting that we will be checking in rebuild-indexes scripts as well. But I do not have a problem per se as long as these get updated when new indices are added.

[nrg4878]

can we add a test that fails if we add a new index to the schema file that is not found in the rebuild-indexes file ? So that way developers will remember to update these files as well?

[soumyakanti3578]

Yes, that is exactly what's being tested in rebuildScriptMatchesInitScript()

    Pattern pattern = PATTERNS.get(dbType);
    Set<String> initIndexes = extractIndexNames(schemaScript, pattern);
    Set<String> rebuildIndexes = extractIndexNames(rebuildScript, pattern);

    Set<String> missing = new HashSet<>(initIndexes);
    missing.removeAll(rebuildIndexes);

    Set<String> extra = new HashSet<>(rebuildIndexes);
    extra.removeAll(initIndexes);

    assertTrue("Indexes in init script missing from rebuild script: " + missing, missing.isEmpty());
    assertTrue("Indexes in rebuild script not found in init script: " + extra, extra.isEmpty());

and it tests extra indexes in the rebuild scripts too, so devs can remember to remove them if we ever remove an index from the schema file.