From d1662abccb91be4844efc1508ff8b0427019a27c Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Wed, 1 Apr 2020 21:50:16 +0300
Subject: Prepare to replacing package buildable flag with enumeration

Note that changing the data member type is not automatically handled by the
ODB migration machinery. Thus, we split the schema change into two steps, with
this commit implementing the first step (see migrate/migrate.cxx for details).
---
 libbrep/build-extra.sql   |  2 +-
 libbrep/build-package.hxx |  2 ++
 libbrep/build.hxx         |  2 +-
 libbrep/build.xml         |  2 ++
 libbrep/package.hxx       |  4 +++-
 libbrep/package.xml       |  7 +++++++
 migrate/migrate.cxx       | 23 +++++++++++++++++++++--
 7 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/libbrep/build-extra.sql b/libbrep/build-extra.sql
index 9ecbcb1..7b9fec5 100644
--- a/libbrep/build-extra.sql
+++ b/libbrep/build-extra.sql
@@ -49,7 +49,7 @@ CREATE FOREIGN TABLE build_package (
   version_release TEXT NULL,
   internal_repository_tenant TEXT NULL,
   internal_repository_canonical_name TEXT NULL,
-  buildable BOOLEAN NOT NULL)
+  buildable_ BOOLEAN NOT NULL)
 SERVER package_server OPTIONS (table_name 'package');
 
 -- The foreign table for the build_package object builds member (that is of a
diff --git a/libbrep/build-package.hxx b/libbrep/build-package.hxx
index 702f937..ffa9d0b 100644
--- a/libbrep/build-package.hxx
+++ b/libbrep/build-package.hxx
@@ -96,6 +96,8 @@ namespace brep
     #pragma db member(builds) id_column("") value_column("")
     #pragma db member(constraints) id_column("") value_column("")
 
+    #pragma db member(buildable) column("buildable_")
+
   private:
     friend class odb::access;
     build_package () = default;
diff --git a/libbrep/build.hxx b/libbrep/build.hxx
index 83b30a8..a883fa0 100644
--- a/libbrep/build.hxx
+++ b/libbrep/build.hxx
@@ -25,7 +25,7 @@
 //
 #define LIBBREP_BUILD_SCHEMA_VERSION_BASE 9
 
-#pragma db model version(LIBBREP_BUILD_SCHEMA_VERSION_BASE, 10, closed)
+#pragma db model version(LIBBREP_BUILD_SCHEMA_VERSION_BASE, 11, closed)
 
 // We have to keep these mappings at the global scope instead of inside
 // the brep namespace because they need to be also effective in the
diff --git a/libbrep/build.xml b/libbrep/build.xml
index bf8920b..f4ba6cb 100644
--- a/libbrep/build.xml
+++ b/libbrep/build.xml
@@ -1,4 +1,6 @@
 <changelog xmlns="http://www.codesynthesis.com/xmlns/odb/changelog" database="pgsql" schema-name="build" version="1">
+  <changeset version="11"/>
+
   <changeset version="10">
     <alter-table name="build">
       <add-column name="completion_timestamp" type="BIGINT" null="false" default="0"/>
diff --git a/libbrep/package.hxx b/libbrep/package.hxx
index 07bd2a0..f679c62 100644
--- a/libbrep/package.hxx
+++ b/libbrep/package.hxx
@@ -20,7 +20,7 @@
 //
 #define LIBBREP_PACKAGE_SCHEMA_VERSION_BASE 17
 
-#pragma db model version(LIBBREP_PACKAGE_SCHEMA_VERSION_BASE, 17, closed)
+#pragma db model version(LIBBREP_PACKAGE_SCHEMA_VERSION_BASE, 18, closed)
 
 namespace brep
 {
@@ -583,6 +583,8 @@ namespace brep
     #pragma db member(other_repositories)                     \
       id_column("") value_column("repository_") value_not_null
 
+    #pragma db member(buildable) column("buildable_")
+
     // search_index
     //
     #pragma db member(search_index) virtual(weighted_text) null \
diff --git a/libbrep/package.xml b/libbrep/package.xml
index 785ae0f..292cd05 100644
--- a/libbrep/package.xml
+++ b/libbrep/package.xml
@@ -1,4 +1,11 @@
 <changelog xmlns="http://www.codesynthesis.com/xmlns/odb/changelog" database="pgsql" schema-name="package" version="1">
+  <changeset version="18">
+    <alter-table name="package">
+      <add-column name="buildable_" type="BOOLEAN" null="false"/>
+      <drop-column name="buildable"/>
+    </alter-table>
+  </changeset>
+
   <model version="17">
     <table name="tenant" kind="object">
       <column name="id" type="TEXT" null="false"/>
diff --git a/migrate/migrate.cxx b/migrate/migrate.cxx
index 81c4543..1577f1b 100644
--- a/migrate/migrate.cxx
+++ b/migrate/migrate.cxx
@@ -206,7 +206,6 @@ create (database& db, bool extra_only) const
 
 // Register the data migration functions for the package database schema.
 //
-#if 0
 template <schema_version v>
 using package_migration_entry_base =
   data_migration_entry<v, LIBBREP_PACKAGE_SCHEMA_VERSION_BASE>;
@@ -218,11 +217,31 @@ struct package_migration_entry: package_migration_entry_base<v>
       : package_migration_entry_base<v> (f, "package") {}
 };
 
+// Migrate the package buildable member data while changing its type from
+// boolean to enumeration.
+
+// Note that changing the data member type is not automatically handled by the
+// migration machinery. Thus, we split the schema change into two steps,
+// delaying the second step until the next commit:
+//
+// - Rename the buildable data member column preserving its boolean type and
+//   migrate the data copying it from the original column into the new
+//   temporary column (package schema version 18). Note that the original
+//   column is deleted at the end of the migration.
+//
+// - Change the buildable data member type to the buildable_status
+//   enumeration, revert the column name and migrate the data by filling the
+//   originally-named column based on the temporary column (package schema
+//   version 19). Note that the temporary column is deleted at the end of the
+//   migration.
+//
 static const package_migration_entry<18>
 package_migrate_v18 ([] (database& db)
 {
+  // Copy the buildable flag values into the new temporary column.
+  //
+  db.execute ("UPDATE package SET buildable_ = buildable");
 });
-#endif
 
 // main() function
 //
-- 
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