Adds Citus compatibility with PG18.1 (#8065)

Adds Citus compatibility with PostgreSQL 18.1 by wiring PG18 into the
devcontainer, configure checks, and CI matrices.

### Summary

- Build PostgreSQL 18.1 in the devcontainer image via `pgenv` and stage
its artifacts alongside existing PG16–PG17 installs.
- Switch the default devcontainer PostgreSQL version to 18.1 so local
developer workflows exercise PG18 by default.
- Extend `configure` / `configure.ac` version checks to treat PostgreSQL
18 as a supported server version.
- Update GitHub Actions `build_and_test.yml` to:
  - Define a `pg18_version` entry (`major: 18`, `full: 18.1`).
- Add PG18 to all relevant test matrices (check-split, check-multi,
regress, enterprise, pytest, CDC installcheck, and query-generator).
- Include upgrade paths to PG18 (16→18, 17→18) in the upgrade-test
matrix.
  - Run the flakiness job against the PG18 fail-tester image.
- Update `packaging-test-pipelines.yml` so the supported PG version list
is derived more robustly from `build_and_test.yml` (no assumptions about
version suffixes).
- Extend `src/test/regress/citus_tests/common.py` with the
OLDEST_SUPPORTED_CITUS_VERSION mapping for PG18 to keep upgrade tests
working.

### Testing

- Devcontainer image builds successfully and `pgenv switch 18.1` works
inside the container.
- GitHub Actions:
- `build_and_test.yml` matrix includes the new PG18 jobs and they
complete successfully.
- `packaging-test-pipelines.yml` still discovers the expected set of
PostgreSQL versions.

---------

Co-authored-by: Colm <colm.mchugh@gmail.com>
Co-authored-by: naisila <nicypp@gmail.com>
Co-authored-by: Naisila Puka <37271756+naisila@users.noreply.github.com>

.devcontainer/Dockerfile

@@ -96,6 +96,18 @@ RUN mkdir .pgenv-staging/
 RUN cp -r .pgenv/src .pgenv/pgsql-* .pgenv/config .pgenv-staging/
 RUN rm .pgenv-staging/config/default.conf
 
+FROM base AS pg18
+RUN MAKEFLAGS="-j $(nproc)" pgenv build 18.1
+RUN rm .pgenv/src/*.tar*
+RUN make -C .pgenv/src/postgresql-*/ clean
+RUN make -C .pgenv/src/postgresql-*/src/include install
+
+# Stage the pgenv artifacts for PG18
+RUN mkdir .pgenv-staging/
+RUN cp -r .pgenv/src .pgenv/pgsql-* .pgenv/config .pgenv-staging/
+RUN rm .pgenv-staging/config/default.conf
+
+
 FROM base AS uncrustify-builder
 
 RUN sudo apt update && sudo apt install -y cmake tree
@@ -188,6 +200,7 @@ COPY --link --from=uncrustify-builder /uncrustify/usr/ /usr/
 
 COPY --link --from=pg16 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
 COPY --link --from=pg17 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
+COPY --link --from=pg18 /home/citus/.pgenv-staging/ /home/citus/.pgenv/
 
 COPY --link --from=pipenv /home/citus/.local/share/virtualenvs/ /home/citus/.local/share/virtualenvs/
 
@@ -203,7 +216,7 @@ COPY --chown=citus:citus .psqlrc .
 RUN sudo chown --from=root:root citus:citus -R ~
 
 # sets default pg version
-RUN pgenv switch 17.7
+RUN pgenv switch 18.1
 
 # make connecting to the coordinator easy
 ENV PGPORT=9700

.github/workflows/build_and_test.yml

@@ -31,11 +31,12 @@ jobs:
       pgupgrade_image_name: "ghcr.io/citusdata/pgupgradetester"
       style_checker_image_name: "ghcr.io/citusdata/stylechecker"
       style_checker_tools_version: "0.8.33"
-      sql_snapshot_pg_version: "17.7"
-      image_suffix: "-vafdc5ac"
+      sql_snapshot_pg_version: "18.1"
+      image_suffix: "-v15cd08f"
       pg16_version: '{ "major": "16", "full": "16.11" }'
       pg17_version: '{ "major": "17", "full": "17.7" }'
-      upgrade_pg_versions: "16.11-17.7"
+      pg18_version: '{ "major": "18", "full": "18.1" }'
+      upgrade_pg_versions: "16.11-17.7-18.1"
     steps:
       # Since GHA jobs need at least one step we use a noop step here.
       - name: Set up parameters
@@ -111,6 +112,7 @@ jobs:
         pg_version:
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
+          - ${{ needs.params.outputs.pg18_version }}
     runs-on: ubuntu-latest
     container:
       image: "${{ matrix.image_name }}:${{ fromJson(matrix.pg_version).full }}${{ matrix.image_suffix }}"
@@ -141,6 +143,7 @@ jobs:
         pg_version:
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
+          - ${{ needs.params.outputs.pg18_version }}
         make:
           - check-split
           - check-multi
@@ -167,6 +170,10 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
+          - make: check-failure
+            pg_version: ${{ needs.params.outputs.pg18_version }}
+            suite: regress
+            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-enterprise-failure
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -175,6 +182,10 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
+          - make: check-enterprise-failure
+            pg_version: ${{ needs.params.outputs.pg18_version }}
+            suite: regress
+            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: check-pytest
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -183,6 +194,10 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
+          - make: check-pytest
+            pg_version: ${{ needs.params.outputs.pg18_version }}
+            suite: regress
+            image_name: ${{ needs.params.outputs.fail_test_image_name }}
           - make: installcheck
             suite: cdc
             image_name: ${{ needs.params.outputs.test_image_name }}
@@ -191,6 +206,10 @@ jobs:
             suite: cdc
             image_name: ${{ needs.params.outputs.test_image_name }}
             pg_version: ${{ needs.params.outputs.pg17_version }}
+          - make: installcheck
+            suite: cdc
+            image_name: ${{ needs.params.outputs.test_image_name }}
+            pg_version: ${{ needs.params.outputs.pg18_version }}
           - make: check-query-generator
             pg_version: ${{ needs.params.outputs.pg16_version }}
             suite: regress
@@ -199,6 +218,10 @@ jobs:
             pg_version: ${{ needs.params.outputs.pg17_version }}
             suite: regress
             image_name: ${{ needs.params.outputs.fail_test_image_name }}
+          - make: check-query-generator
+            pg_version: ${{ needs.params.outputs.pg18_version }}
+            suite: regress
+            image_name: ${{ needs.params.outputs.fail_test_image_name }}
     runs-on: ubuntu-latest
     container:
       image: "${{ matrix.image_name }}:${{ fromJson(matrix.pg_version).full }}${{ needs.params.outputs.image_suffix }}"
@@ -247,6 +270,7 @@ jobs:
         pg_version:
           - ${{ needs.params.outputs.pg16_version }}
           - ${{ needs.params.outputs.pg17_version }}
+          - ${{ needs.params.outputs.pg18_version }}
         parallel: [0,1,2,3,4,5] # workaround for running 6 parallel jobs
     steps:
     - uses: actions/checkout@v4
@@ -293,6 +317,10 @@ jobs:
         include:
           - old_pg_major: 16
             new_pg_major: 17
+          - old_pg_major: 17
+            new_pg_major: 18
+          - old_pg_major: 16
+            new_pg_major: 18
     env:
       old_pg_major: ${{ matrix.old_pg_major }}
       new_pg_major: ${{ matrix.new_pg_major }}
@@ -486,7 +514,7 @@ jobs:
     name: Test flakyness
     runs-on: ubuntu-latest
     container:
-      image: ${{ needs.params.outputs.fail_test_image_name }}:${{ fromJson(needs.params.outputs.pg17_version).full }}${{ needs.params.outputs.image_suffix }}
+      image: ${{ needs.params.outputs.fail_test_image_name }}:${{ fromJson(needs.params.outputs.pg18_version).full }}${{ needs.params.outputs.image_suffix }}
       options: --user root
     env:
       runs: 8

.github/workflows/packaging-test-pipelines.yml

@@ -29,7 +29,7 @@ jobs:
           # Postgres versions are stored in .github/workflows/build_and_test.yml
           # file in json strings with major and full keys.
           # Below command extracts the versions and get the unique values.
-          pg_versions=$(cat .github/workflows/build_and_test.yml | grep -oE '"major": "[0-9]+", "full": "[0-9.]+"' | sed -E 's/"major": "([0-9]+)", "full": "([0-9.]+)"/\1/g' | sort | uniq | tr '\n', ',')
+          pg_versions=$(cat .github/workflows/build_and_test.yml | grep -oE '"major": "[0-9]+", "full": "[^"]+"' | sed -E 's/.*"major": "([0-9]+)".*/\1/' | sort -n | uniq | tr '\n' ',')
           pg_versions_array="[ ${pg_versions} ]"
           echo "Supported PG Versions: ${pg_versions_array}"
           # Below line is needed to set the output variable to be used in the next job
@@ -122,6 +122,10 @@ jobs:
           - ubuntu-jammy-all
 
         POSTGRES_VERSION: ${{ fromJson(needs.get_postgres_versions_from_file.outputs.pg_versions) }}
+        exclude:
+          # PG18 is not supported on Ubuntu focal
+          - packaging_docker_image: ubuntu-focal-all
+            POSTGRES_VERSION: 18
 
     container:
       image: citus/packaging:${{ matrix.packaging_docker_image }}

configure

@@ -2549,11 +2549,13 @@ fi
 
 # check we're building against a supported version of PostgreSQL
 citusac_pg_config_version=$($PG_CONFIG --version 2>/dev/null)
-version_num=$(echo "$citusac_pg_config_version"|
-              $SED -e 's/^PostgreSQL \([0-9]*\)\(\.[0-9]*\)\{0,1\}\(.*\)$/\1\2/')
+# Extract major[.minor] from "PostgreSQL X[.Y] ..."
+version_num=$(printf '%s\n' "$citusac_pg_config_version" \
+  | $SED -nE 's/^PostgreSQL[[:space:]]+([0-9]+(\.[0-9]+)?).*/\1/p')
 
-# if PostgreSQL version starts with two digits, the major version is those digits
-version_num=$(echo "$version_num"| $SED -e 's/^\([0-9]\{2\}\)\(.*\)$/\1/')
+# If it starts with two digits (10+), keep only the major.
+version_num=$(printf '%s\n' "$version_num" \
+  | $SED -E 's/^([0-9]{2}).*$/\1/')
 
 if test -z "$version_num"; then
   as_fn_error $? "Could not detect PostgreSQL version from pg_config." "$LINENO" 5
@@ -2588,7 +2590,7 @@ fi
 if test "$with_pg_version_check" = no; then
     { $as_echo "$as_me:${as_lineno-$LINENO}: building against PostgreSQL $version_num (skipped compatibility check)" >&5
 $as_echo "$as_me: building against PostgreSQL $version_num (skipped compatibility check)" >&6;}
-elif test "$version_num" != '16' -a  "$version_num" != '17'; then
+elif test "$version_num" != '16' -a  "$version_num" != '17' -a "$version_num" != '18'; then
    as_fn_error $? "Citus is not compatible with the detected PostgreSQL version ${version_num}." "$LINENO" 5
 else
    { $as_echo "$as_me:${as_lineno-$LINENO}: building against PostgreSQL $version_num" >&5

configure.ac

@@ -80,7 +80,7 @@ AC_SUBST(with_pg_version_check)
 
 if test "$with_pg_version_check" = no; then
     AC_MSG_NOTICE([building against PostgreSQL $version_num (skipped compatibility check)])
-elif test "$version_num" != '16' -a  "$version_num" != '17'; then
+elif test "$version_num" != '16' -a  "$version_num" != '17' -a  "$version_num" != '18'; then
    AC_MSG_ERROR([Citus is not compatible with the detected PostgreSQL version ${version_num}.])
 else
    AC_MSG_NOTICE([building against PostgreSQL $version_num])

src/test/regress/citus_tests/common.py

@@ -94,6 +94,7 @@ OLDEST_SUPPORTED_CITUS_VERSION_MATRIX = {
     15: "11.1.5",
     16: "12.1.5",
     17: "13.0.1",
+    18: "14.0devel",
 }
 
 OLDEST_SUPPORTED_CITUS_VERSION = OLDEST_SUPPORTED_CITUS_VERSION_MATRIX[PG_MAJOR_VERSION]