Fix ALTER TABLE ... DROP CONSTRAINT not to happen against non existing tables or constraints.

src/package.lisp

@@ -56,6 +56,7 @@
 	   #:list-tables
 	   #:list-columns
 	   #:list-tables-cols
+	   #:list-tables-and-fkeys
 	   #:list-reserved-keywords
 	   #:reset-all-sequences
 	   #:get-date-columns
@@ -145,6 +146,7 @@
 		#:pgsql-execute
 		#:pgsql-execute-with-timing
 		#:apply-identifier-case
+		#:list-tables-and-fkeys
 		#:create-tables
 		#:format-pgsql-column
 		#:format-extra-type

src/pgsql/queries.lisp

@@ -126,6 +126,17 @@ select relname, array_agg(case when typname in ('date', 'timestamptz')
 " schema table-name-list))
        collect (cons relname cols))))
 
+(defun list-tables-and-fkeys (&optional schema)
+  "Yet another table listing query."
+  (loop for (relname fkeys) in (pomo:query (format nil "
+  select relname, array_to_string(array_agg(conname), ',')
+    from pg_class c
+         join pg_namespace n on n.oid = c.relnamespace
+         left join pg_constraint co on c.oid = co.conrelid
+    where contype = 'f' and nspname = ~:[current_schema()~;'~a'~]
+ group by relname;" schema schema))
+     collect (cons relname (sq:split-sequence #\, fkeys))))
+
 (defun list-columns (dbname table-name &key schema)
   "Return a list of column names for given TABLE-NAME."
   (pomo:with-connection

src/pgsql/schema.lisp

@@ -85,15 +85,19 @@
 	    foreign-table
 	    (pgsql-fkey-foreign-columns fk))))
 
-(defmethod format-pgsql-drop-fkey ((fk pgsql-fkey) &key identifier-case)
+(defmethod format-pgsql-drop-fkey ((fk pgsql-fkey)
+				   &key all-pgsql-fkeys identifier-case)
   "Generate the PostgreSQL statement to rebuild a MySQL Foreign Key"
   (let* ((constraint-name
 	  (apply-identifier-case (pgsql-fkey-name fk) identifier-case))
 	 (table-name
-	  (apply-identifier-case (pgsql-fkey-table-name fk) identifier-case)))
-    ;; beware, IF EXISTS is only supported from 9.0 onward...
-    (format nil "alter table ~a drop constraint if exists ~a"
-	    table-name constraint-name)))
+	  (apply-identifier-case (pgsql-fkey-table-name fk) identifier-case))
+	 (fkeys         (cdr (assoc table-name all-pgsql-fkeys :test #'string=)))
+	 (fkey-exists   (member constraint-name fkeys :test #'string=)))
+    (when fkey-exists
+      ;; we could do that without all-pgsql-fkeys in 9.2 and following with:
+      ;; alter table if exists ... drop constraint if exists ...
+      (format nil "ALTER TABLE ~a DROP CONSTRAINT ~a" table-name constraint-name))))
 
 
 ;;;

src/sources/mysql-schema.lisp

@@ -232,13 +232,19 @@ GROUP BY table_name, index_name;" dbname)))
     ;; free resources
     (cl-mysql:disconnect)))
 
-(defun drop-fkeys (all-fkeys &key identifier-case)
+(defun drop-fkeys (all-fkeys &key dbname identifier-case)
   "Drop all Foreign Key Definitions given, to prepare for a clean run."
-  (loop for (table-name . fkeys) in all-fkeys
-     do
-       (loop for fkey in fkeys
-	  for sql = (format-pgsql-drop-fkey fkey :identifier-case identifier-case)
-	  do (pgsql-execute sql))))
+  (let ((all-pgsql-fkeys (list-tables-and-fkeys dbname)))
+    (loop for (table-name . fkeys) in all-fkeys
+       do
+	 (loop for fkey in fkeys
+	    for sql = (format-pgsql-drop-fkey fkey
+					      :all-pgsql-fkeys all-pgsql-fkeys
+					      :identifier-case identifier-case)
+	    when sql
+	    do
+	      (log-message :notice "~a;" sql)
+	      (pgsql-execute sql)))))
 
 (defun create-fkeys (all-fkeys
 		     &key
@@ -251,7 +257,7 @@ GROUP BY table_name, index_name;" dbname)))
 	   for sql =
 	     (format-pgsql-create-fkey fkey :identifier-case identifier-case)
 	   do
-	     (log-message :notice "~a" sql)
+	     (log-message :notice "~a;" sql)
 	     (pgsql-execute-with-timing dbname "Foreign Keys" sql state))))
 
 

src/sources/mysql.lisp

@@ -239,6 +239,7 @@
 	  ;; can DROP TABLE when asked
 	  (when (and foreign-keys include-drop)
 	    (drop-fkeys all-fkeys
+			:dbname pg-dbname
 			:identifier-case identifier-case))
 
 	  ;; now drop then create tables and types, etc