diff --git a/.travis.yml b/.travis.yml
index 6a508919c72..6dd1adf6629 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -81,8 +81,7 @@ jobs:
         - distribution/bin/generate-license-dependency-reports.py . target --clean-maven-artifact-transfer --parallel 2
         - distribution/bin/check-licenses.py licenses.yaml target/license-reports
 
-    - &compile_strict
-      name: "(openjdk8) strict compilation"
+    - name: "(openjdk8) strict compilation"
       install: skip
       # Strict compilation requires more than 2 GB
       script: >
@@ -136,20 +135,52 @@ jobs:
 
     - &test_processing_module
       name: "(openjdk8) processing module test"
-      env: &processing_env
+      env:
       - MAVEN_PROJECTS='processing'
-      before_script: &setup_java_test
+      before_script:
+        - export DRUID_USE_DEFAULT_VALUE_FOR_NULL=true
+      script:
         - unset _JAVA_OPTIONS
-      script: &run_java_test
         # Set MAVEN_OPTS for Surefire launcher. Skip remoteresources to avoid intermittent connection timeouts when
         # resolving the SIGAR dependency.
         - >
           MAVEN_OPTS='-Xmx800m' ${MVN} test -pl ${MAVEN_PROJECTS}
-          ${MAVEN_SKIP} -Dremoteresources.skip=true
+          ${MAVEN_SKIP} -Dremoteresources.skip=true -Ddruid.generic.useDefaultValueForNull=${DRUID_USE_DEFAULT_VALUE_FOR_NULL}
         - sh -c "dmesg | egrep -i '(oom|out of memory|kill process|killed).*' -C 1 || exit 0"
         - free -m
-      after_success: &upload_java_unit_test_coverage
         - ${MVN} -pl ${MAVEN_PROJECTS} jacoco:report
+        # Add merge target branch to determine diff (see https://github.com/travis-ci/travis-ci/issues/6069)
+        - echo "TRAVIS_BRANCH=${TRAVIS_BRANCH}"  # for debugging
+        - git remote set-branches --add origin ${TRAVIS_BRANCH} && git fetch
+        # Determine the modified files that match the maven projects being tested. We use maven project lists that
+        # either exclude (starts with "!") or include (does not start with "!"), so both cases need to be handled.
+        - all_files="$(git diff --name-only origin/${TRAVIS_BRANCH}...HEAD | grep "\.java$" || [[ $? == 1 ]])"
+        - for f in ${all_files}; do echo $f; done  # for debugging
+        - >
+          if [[ "${MAVEN_PROJECTS}" = \!* ]]; then
+          regex="${MAVEN_PROJECTS:1}";
+          regex="^${regex//,\!/\\|^}";
+          project_files="$(echo "${all_files}" | grep -v "${regex}" || [[ $? == 1 ]])";
+          else
+          regex="^${MAVEN_PROJECTS//,/\\|^}";
+          project_files="$(echo "${all_files}" | grep "${regex}" || [[ $? == 1 ]])";
+          fi
+        - for f in ${project_files}; do echo $f; done  # for debugging
+        # Check diff code coverage for the maven projects being tested (retry install in case of network error)
+        - >
+          if [ -n "${project_files}" ]; then
+          travis_retry npm install @connectis/diff-test-coverage@1.5.3
+          && git diff origin/${TRAVIS_BRANCH}...HEAD -- ${project_files}
+          | node_modules/.bin/diff-test-coverage
+          --coverage "**/target/site/jacoco/jacoco.xml"
+          --type jacoco
+          --line-coverage 65
+          --branch-coverage 65
+          --function-coverage 80
+          --
+          || { printf "\nDiff code coverage check failed. To view coverage report, run 'mvn clean test jacoco:report' and open 'target/site/jacoco/index.html'\n" && false; }
+          fi
+      after_success:
         # retry in case of network error
         - travis_retry curl -o codecov.sh -s https://codecov.io/bash
         - travis_retry bash codecov.sh -X gcov
@@ -159,89 +190,69 @@ jobs:
       jdk: openjdk11
 
     - &test_processing_module_sqlcompat
+      <<: *test_processing_module
       name: "(openjdk8) processing module test (SQL Compatibility)"
-      env: *processing_env
-      before_script: *setup_java_test
-      script: &run_java_sql_compat_test
-        # Set MAVEN_OPTS for Surefire launcher. Skip remoteresources to avoid intermittent connection timeouts when
-        # resolving the SIGAR dependency.
-        - >
-          MAVEN_OPTS='-Xmx800m' ${MVN} test -pl ${MAVEN_PROJECTS} -Ddruid.generic.useDefaultValueForNull=false
-          ${MAVEN_SKIP} -Dremoteresources.skip=true
-        - sh -c "dmesg | egrep -i '(oom|out of memory|kill process|killed).*' -C 1 || exit 0"
-        - free -m
-      after_success: *upload_java_unit_test_coverage
+      before_script: &setup_sqlcompat
+      - export DRUID_USE_DEFAULT_VALUE_FOR_NULL=false
 
     - <<: *test_processing_module_sqlcompat
       name: "(openjdk11) processing module test (SQL Compatibility)"
       jdk: openjdk11
 
     - &test_indexing_module
+      <<: *test_processing_module
       name: "(openjdk8) indexing modules test"
-      env: &indexing_env
+      env:
       - MAVEN_PROJECTS='indexing-hadoop,indexing-service,extensions-core/kafka-indexing-service,extensions-core/kinesis-indexing-service'
-      before_script: *setup_java_test
-      script: *run_java_test
-      after_success: *upload_java_unit_test_coverage
 
     - <<: *test_indexing_module
       name: "(openjdk11) indexing modules test"
       jdk: openjdk11
 
     - &test_indexing_module_sqlcompat
+      <<: *test_indexing_module
       name: "(openjdk8) indexing modules test (SQL Compatibility)"
-      env: *indexing_env
-      before_script: *setup_java_test
-      script: *run_java_sql_compat_test
-      after_success: *upload_java_unit_test_coverage
+      before_script: *setup_sqlcompat
 
     - <<: *test_indexing_module_sqlcompat
       name: "(openjdk11) indexing modules test (SQL Compatibility)"
       jdk: openjdk11
 
     - &test_server_module
+      <<: *test_processing_module
       name: "(openjdk8) server module test"
-      env: &server_env
+      env:
         - MAVEN_PROJECTS='server'
-      before_script: *setup_java_test
-      script: *run_java_test
-      after_success: *upload_java_unit_test_coverage
 
     - <<: *test_server_module
       name: "(openjdk11) server module test"
       jdk: openjdk11
 
     - &test_server_module_sqlcompat
+      <<: *test_server_module
       name: "(openjdk8) server module test (SQL Compatibility)"
-      env: *server_env
-      before_script: *setup_java_test
-      script: *run_java_sql_compat_test
-      after_success: *upload_java_unit_test_coverage
+      before_script: *setup_sqlcompat
 
     - <<: *test_server_module_sqlcompat
       name: "(openjdk11) server module test (SQL Compatibility)"
       jdk: openjdk11
 
-    - &test_modules
+    - &test_other_modules
+      <<: *test_processing_module
       name: "(openjdk8) other modules test"
-      env: &other_env
+      env:
         - MAVEN_PROJECTS='!processing,!indexing-hadoop,!indexing-service,!extensions-core/kafka-indexing-service,!extensions-core/kinesis-indexing-service,!server,!web-console'
-      before_script: *setup_java_test
-      script: *run_java_test
-      after_success: *upload_java_unit_test_coverage
 
-    - <<: *test_modules
+    - <<: *test_other_modules
       name: "(openjdk11) other modules test"
       jdk: openjdk11
 
-    - &test_modules_sqlcompat
+    - &test_other_modules_sqlcompat
+      <<: *test_other_modules
       name: "(openjdk8) other modules test (SQL Compatibility)"
-      env: *other_env
-      before_script: *setup_java_test
-      script: *run_java_sql_compat_test
-      after_success: *upload_java_unit_test_coverage
+      before_script: *setup_sqlcompat
 
-    - <<: *test_modules_sqlcompat
+    - <<: *test_other_modules_sqlcompat
       name: "(openjdk11) other modules test (SQL Compatibility)"
       jdk: openjdk11
 
diff --git a/benchmarks/pom.xml b/benchmarks/pom.xml
index 15628ec3039..4c640a62fe1 100644
--- a/benchmarks/pom.xml
+++ b/benchmarks/pom.xml
@@ -220,6 +220,13 @@
           <skip>true</skip>
         </configuration>
       </plugin>
+      <plugin>
+        <groupId>org.jacoco</groupId>
+        <artifactId>jacoco-maven-plugin</artifactId>
+        <configuration>
+          <skip>true</skip> <!-- ignore non-production code -->
+        </configuration>
+      </plugin>
     </plugins>
     <pluginManagement>
       <plugins>
diff --git a/pom.xml b/pom.xml
index 5c4cf156d10..aeffceb8a5c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1251,7 +1251,7 @@
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>
-                <version>0.8.4</version>
+                <version>0.8.5</version>
                 <configuration>
                     <excludes>
                         <!-- Ignore generated code -->