feat: add rule dependencies

.github/workflows/checks.yml

@@ -22,7 +22,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install pylint psycopg2
+        pip install pylint psycopg2 packaging
     - name: Analysing the code with pylint
       run: |
         pylint $(git ls-files '*.py')

setup.py

@@ -69,7 +69,8 @@ def get_version(rel_path: str) -> str:
         "Programming Language :: Python :: 3 :: Only",
     ],
     install_requires=[
-          'psycopg2',
+        'psycopg2',
+        'packaging',
       ],
     entry_points={
         "console_scripts": [

src/doctor/__init__.py

@@ -21,6 +21,7 @@
 from textwrap import dedent, fill
 from os.path import dirname, basename, isfile, join
 from abc import ABC
+from packaging.version import parse
 
 import psycopg2
 
@@ -54,14 +55,31 @@ class Rule(ABC):
       optional field. If no field is given, the value of the "message"
       field will be used.
 
+    dependencies: Dictionary with dependencies on packages and what
+    versions that are required.
+
     """
 
+    def get_versions(self, conn):
+        """Get extension versions."""
+        with conn.cursor() as cursor:
+            cursor.execute("SELECT extname, extversion FROM pg_extension WHERE extname IN %s",
+                           (tuple(self.dependencies.keys()),)) # pylint: disable=E1101
+            return {row["extname"]: row["extversion"] for row in cursor}
+
+
     def execute(self, conn, text):
         """Execute rule and return one string for each mismatching object."""
-        cursor = conn.cursor()
-        cursor.execute(self.query) # pylint: disable=E1101
-        return [text.format(**kwrds) for kwrds in cursor]
-
+        with conn.cursor() as cursor:
+            # Check that all dependencies are met. If not, we do not
+            # execute the rule.
+            if hasattr(self, 'dependencies'):
+                versions = self.get_versions(conn)
+                for ext,req in self.dependencies.items(): # pylint: disable=E1101
+                    if ext not in versions or parse(req) > parse(versions[ext]):
+                        return []
+            cursor.execute(self.query) # pylint: disable=E1101
+            return [text.format(**kwrds) for kwrds in cursor]
 
 def register(cls):
     """Register a rule."""

src/doctor/rules/compression.py

@@ -14,8 +14,6 @@
 
 """Rules for compressed hypertables."""
 
-from dataclasses import dataclass
-
 import doctor
 
 LINEAR_QUERY = """
@@ -30,7 +28,6 @@
 """
 
 @doctor.register
-@dataclass
 class LinearSegmentby(doctor.Rule):
     """Detect segmentby column for compressed table."""
 
@@ -44,6 +41,9 @@ class LinearSegmentby(doctor.Rule):
         " with the number of rows of the table."
 
     )
+    dependencies: dict = {
+        'timescaledb': '1.0'
+    }
 
 POINTLESS_QUERY = """
 SELECT format('%I.%I', schema_name, table_name)::regclass AS relation, s.attname
@@ -57,7 +57,6 @@ class LinearSegmentby(doctor.Rule):
 """
 
 @doctor.register
-@dataclass
 class PointlessSegmentBy(doctor.Rule):
     """Detect pointless segmentby column in compressed table."""
 
@@ -69,3 +68,6 @@ class PointlessSegmentBy(doctor.Rule):
         "Column '{attname}' in hypertable '{relation}' as segment-by column is pointless"
         " since it contains a single value."
     )
+    dependencies: dict = {
+        'timescaledb': '1.0'
+    }

src/doctor/rules/hypertable.py

@@ -14,8 +14,6 @@
 
 """Rules for hypertables."""
 
-from dataclasses import dataclass
-
 import doctor
 
 CANDIDATE_QUERY = """
@@ -49,7 +47,6 @@
 """
 
 @doctor.register
-@dataclass
 class HypertableCandidate(doctor.Rule):
     """Detect candidate hypertable."""
 
@@ -72,9 +69,11 @@ class HypertableCandidate(doctor.Rule):
 """
 
 @doctor.register
-@dataclass
 class ChunkPermissions(doctor.Rule):
     """Detect bad chunk permissions."""
 
     query: str = PERMISSION_QUERY
     message: str = "Chunk '{chunk}' have different permissions from hypertable '{hypertable}'."
+    dependencies: dict = {
+        'timescaledb': '1.0'
+    }