From 25f919576fb29681fc6fb5ad5c2df8b06004a40d Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Tue, 12 Apr 2016 15:03:19 -0700
Subject: [PATCH] Add very basic infrastructure for schema upgrade scripts.

Citus' extension version now has a -$schemaversion appendix.  When the
schema is changed, a new schema version has to be added; changes to the
same schema version several commits inside a single pull request are ok.

Schema migration scripts between each schema version have to be
added. To ensure upgrade scripts work correctly a new regression test
ensures that all steps work.

The extension scripts to-be-used for CREATE EXTENSION (i.e. not
extension updates) are generated by concatenating citus.sql and the
relevant migration scripts.
---
 src/backend/distributed/Makefile              | 14 +++++++++----
 src/backend/distributed/citus--5.0--5.0-1.sql |  3 +++
 src/backend/distributed/citus.control         |  2 +-
 src/test/regress/expected/multi_extension.out | 17 ++++++++++++++++
 src/test/regress/multi_schedule               |  1 +
 src/test/regress/sql/multi_extension.sql      | 20 +++++++++++++++++++
 6 files changed, 52 insertions(+), 5 deletions(-)
 create mode 100644 src/backend/distributed/citus--5.0--5.0-1.sql
 create mode 100644 src/test/regress/expected/multi_extension.out
 create mode 100644 src/test/regress/sql/multi_extension.sql

diff --git a/src/backend/distributed/Makefile b/src/backend/distributed/Makefile
index 039d1e8b4..fd9b920e9 100644
--- a/src/backend/distributed/Makefile
+++ b/src/backend/distributed/Makefile
@@ -5,8 +5,11 @@ citus_top_builddir = ../../..
 
 MODULE_big = citus
 EXTENSION = citus
-EXTVERSION = 5.0
-DATA_built = $(EXTENSION)--$(EXTVERSION).sql
+EXTVERSIONS = 5.0 5.0-1
+# All citus--*.sql files in the source directory
+DATA = $(patsubst $(citus_abs_srcdir)/%.sql,%.sql,$(wildcard $(citus_abs_srcdir)/$(EXTENSION)--*--*.sql))
+# Generated files for each version
+DATA_built = $(foreach v,$(EXTVERSIONS),$(EXTENSION)--$(v).sql)
 SCRIPTS = ../../bin/scripts/copy_to_distributed_table
 
 # directories with source files
@@ -20,8 +23,11 @@ OBJS += \
 # be explicit about the default target
 all:
 
-# define build process for latest install file
-$(EXTENSION)--$(EXTVERSION).sql: $(EXTENSION).sql
+# generate each version's file installation file by concatenating
+# previous upgrade scripts
+$(EXTENSION)--5.0.sql: $(EXTENSION).sql
+	cat $^ > $@
+$(EXTENSION)--5.0-1.sql: $(EXTENSION)--5.0.sql $(EXTENSION)--5.0--5.0-1.sql
 	cat $^ > $@
 
 NO_PGXS = 1
diff --git a/src/backend/distributed/citus--5.0--5.0-1.sql b/src/backend/distributed/citus--5.0--5.0-1.sql
new file mode 100644
index 000000000..8c9e7938d
--- /dev/null
+++ b/src/backend/distributed/citus--5.0--5.0-1.sql
@@ -0,0 +1,3 @@
+/* citus--5.0--5.0-1.sql */
+
+-- Currently nothing to do here
diff --git a/src/backend/distributed/citus.control b/src/backend/distributed/citus.control
index 0f25b1dd7..7db6e73fd 100644
--- a/src/backend/distributed/citus.control
+++ b/src/backend/distributed/citus.control
@@ -1,6 +1,6 @@
 # Citus extension
 comment = 'Citus distributed database'
-default_version = '5.0'
+default_version = '5.0-1'
 module_pathname = '$libdir/citus'
 relocatable = false
 schema = pg_catalog
diff --git a/src/test/regress/expected/multi_extension.out b/src/test/regress/expected/multi_extension.out
new file mode 100644
index 000000000..6175881af
--- /dev/null
+++ b/src/test/regress/expected/multi_extension.out
@@ -0,0 +1,17 @@
+--
+-- MULTI_EXTENSION
+--
+-- Tests around extension creation / upgrades
+--
+-- It'd be nice to script generation of this file, but alas, that's
+-- not done yet.
+-- DROP EXTENSION pre-created by the regression suite
+DROP EXTENSION citus;
+\c
+-- Create extension in oldest version, test every upgrade step
+CREATE EXTENSION citus VERSION '5.0';
+ALTER EXTENSION citus UPDATE TO '5.0-1';
+-- drop extension an re-create in newest version
+DROP EXTENSION citus;
+\c
+CREATE EXTENSION citus;
diff --git a/src/test/regress/multi_schedule b/src/test/regress/multi_schedule
index 751243b5a..546d69b11 100644
--- a/src/test/regress/multi_schedule
+++ b/src/test/regress/multi_schedule
@@ -11,6 +11,7 @@
 # ---
 # Tests around schema changes, these are run first, so there's no preexisting objects.
 # ---
+test: multi_extension
 test: multi_table_ddl
 
 # ----------
diff --git a/src/test/regress/sql/multi_extension.sql b/src/test/regress/sql/multi_extension.sql
new file mode 100644
index 000000000..7c851e1e1
--- /dev/null
+++ b/src/test/regress/sql/multi_extension.sql
@@ -0,0 +1,20 @@
+--
+-- MULTI_EXTENSION
+--
+-- Tests around extension creation / upgrades
+--
+-- It'd be nice to script generation of this file, but alas, that's
+-- not done yet.
+
+-- DROP EXTENSION pre-created by the regression suite
+DROP EXTENSION citus;
+\c
+
+-- Create extension in oldest version, test every upgrade step
+CREATE EXTENSION citus VERSION '5.0';
+ALTER EXTENSION citus UPDATE TO '5.0-1';
+
+-- drop extension an re-create in newest version
+DROP EXTENSION citus;
+\c
+CREATE EXTENSION citus;