Chore: fail if >1 migration scripts start with the same version (#5038)

Author: georgesittas

.pre-commit-config.yaml

@@ -23,3 +23,8 @@ repos:
         files: *files
         require_serial: true
         exclude: ^(tests/fixtures)
+      - id: valid migrations
+        name: valid migrations
+        entry: tooling/validating_migration_numbers.sh
+        language: system
+        pass_filenames: false

tooling/validating_migration_numbers.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# Navigate to the migrations directory (modify the path if necessary)
+cd "sqlmesh/migrations" || exit 1
+
+
+# Collect all migration files matching the pattern (e.g., v0001_initial.py)
+migration_files=(v*.py)
+
+# Initialize an array to hold migration numbers
+numbers=()
+
+# Extract migration numbers from filenames
+for file in "${migration_files[@]}"; do
+  if [[ $file =~ ^v0*([0-9]+)_ ]]; then
+    num=${BASH_REMATCH[1]}
+    numbers+=("$num")
+  fi
+done
+
+# Check if any migration files were found
+if [[ ${#numbers[@]} -eq 0 ]]; then
+  echo "No migration files found matching the pattern 'v<zero-padded number>_<description>.py'."
+  exit 1
+fi
+
+# Check for duplicate migration numbers
+duplicates=$(printf "%s\n" "${numbers[@]}" | sort | uniq -d)
+if [[ -n $duplicates ]]; then
+  echo "Error: Duplicate migration numbers found: $duplicates"
+  exit 1
+fi
+
+# Sort the migration numbers
+sorted_numbers=($(printf "%s\n" "${numbers[@]}" | sort -n))
+
+# Get the first and last migration numbers
+first_number="${sorted_numbers[0]}"
+last_index=$((${#sorted_numbers[@]} - 1))
+last_number="${sorted_numbers[$last_index]}"
+
+# Check for gaps in the migration sequence
+expected_numbers=($(seq "$first_number" "$last_number"))
+
+if [[ "${sorted_numbers[*]}" != "${expected_numbers[*]}" ]]; then
+  echo "Error: Missing migration numbers in sequence."
+  echo "Expected sequence: ${expected_numbers[*]}"
+  echo "Found sequence:    ${sorted_numbers[*]}"
+  exit 1
+fi
+
+echo "All migration numbers are sequential and without overlaps."
+exit 0