Add the MySQL target schema to the search_path.

In the next release, pgloader defaults to targetting a new schema named the
same as the MySQL database, because that's what makes more sense. But people
are used to having 'public' in the search_path and everything in there.

So when creating our target schema, when migrating from MySQL, arrange it so
that the new schema is in the search_path by issuing a command like:

  ALTER DATABASE plop SET search_path TO public, f1db;

And make this command visible in verbose (NOTICE) mode too, so that user can
see what happens.

Fix #654. I think.

src/package.lisp

@@ -80,6 +80,7 @@
            #:schema-source-name
            #:schema-table-list
            #:schema-view-list
+           #:schema-in-search-path
 
            #:table-name
            #:table-source-name
@@ -402,6 +403,7 @@
 
            #:create-sqltypes
 	   #:create-schemas
+           #:add-to-search-path
 	   #:create-tables
 	   #:create-views
            #:drop-pgsql-fkeys

src/pgsql/pgsql-create-schema.lisp

@@ -88,6 +88,32 @@
        :do (let ((sql (format nil "CREATE SCHEMA ~a;" (schema-name schema))))
              (pgsql-execute sql :client-min-messages client-min-messages)))))
 
+(defun add-to-search-path (catalog
+                           &key
+                             label
+                             (section :post)
+                             (log-level :notice)
+                             (client-min-messages :notice))
+  "Add catalog schemas in the database search_path."
+  (let* ((dbname      (get-current-database))
+         (search-path (list-search-path))
+         (missing-schemas
+          (loop :for schema :in (catalog-schema-list catalog)
+             :for schema-name := (schema-name schema)
+             :when (and (schema-in-search-path schema)
+                        (not (member schema-name search-path :test #'string=)))
+             :collect schema-name)))
+    (when missing-schemas
+      (let ((sql (format nil
+                         "ALTER DATABASE ~a SET search_path TO ~{~a~^, ~};"
+                         dbname
+                         (append search-path missing-schemas))))
+        (pgsql-execute-with-timing section
+                                   label
+                                   sql
+                                   :log-level log-level
+                                   :client-min-messages client-min-messages)))))
+
 (defun create-tables (catalog
                       &key
 			if-not-exists

src/pgsql/pgsql-schema.lisp

@@ -312,6 +312,17 @@
    PostgreSQL connection."
   (pomo:query "SELECT nspname FROM pg_catalog.pg_namespace;" :column))
 
+(defun list-search-path ()
+  "Return the current list of schemas in the Search Path"
+  (pomo:query
+   "SELECT name FROM unnest(pg_catalog.current_schemas(false)) as t(name);"
+   :column))
+
+(defun get-current-database ()
+  "Get the current database name. The catalog name and the connection string
+   name may be different, so just ask PostgreSQL here."
+  (pomo:query "select current_database();" :single))
+
 (defun list-table-oids (table-names)
   "Return an hash table mapping TABLE-NAME to its OID for all table in the
    TABLE-NAMES list. A PostgreSQL connection must be established already."

src/sources/common/db-methods.lisp

@@ -170,6 +170,14 @@
                              :section :post
                              :label "Create Triggers")))
 
+        ;;
+        ;; Add schemas that needs to be in the search_path to the database
+        ;; search_path
+        ;;
+        (add-to-search-path catalog
+                            :section :post
+                            :label "Set Search Path")
+
         ;;
         ;; And now, comments on tables and columns.
         ;;

src/sources/mysql/mysql.lisp

@@ -156,7 +156,8 @@
                              including
                              excluding)
   "MySQL introspection to prepare the migration."
-  (let ((schema        (add-schema catalog (catalog-name catalog)))
+  (let ((schema        (add-schema catalog (catalog-name catalog)
+                                   :in-search-path t))
         (view-names    (unless (eq :all materialize-views)
                          (mapcar #'car materialize-views))))
     (with-stats-collection ("fetch meta data"

src/utils/catalog.lisp

@@ -43,7 +43,7 @@
 ;;; implemented in each source separately.
 ;;;
 (defstruct catalog name schema-list types-without-btree)
-(defstruct schema source-name name catalog table-list view-list)
+(defstruct schema source-name name catalog table-list view-list in-search-path)
 (defstruct table source-name name schema oid comment storage-parameter-list
            ;; field is for SOURCE
            ;; column is for TARGET
@@ -203,12 +203,13 @@
     ;; already cooked table structure, try it and see...
     (table maybe-qualified-name)))
 
-(defmethod add-schema ((catalog catalog) schema-name &key)
+(defmethod add-schema ((catalog catalog) schema-name &key in-search-path)
   "Add SCHEMA-NAME to CATALOG and return the new schema instance."
   (let ((schema (make-schema :catalog catalog
                              :source-name schema-name
                              :name (when schema-name
-                                     (apply-identifier-case schema-name)))))
+                                     (apply-identifier-case schema-name))
+                             :in-search-path in-search-path)))
     (push-to-end schema (catalog-schema-list catalog))))
 
 (defmethod add-table ((schema schema) table-name &key comment oid)