From 1bcaf267b389a0e05fdfce2fca5c0a192a8cbb51 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Thu, 18 Oct 2012 00:43:45 +0100
Subject: [PATCH] Stop database processing if library version doesn't match the
 binary

Actually this leaves out the case of the SQL schema not consistent with the
library/binary installed, and this is a relatively likely case:
the user has run "make install" but the repack schema was already loaded
from an older version.
---
 bin/pg_repack.c   | 40 +++++++++++++++++++++++++++++++++++++++-
 doc/pg_repack.rst |  9 +++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/bin/pg_repack.c b/bin/pg_repack.c
index 98ce7b5..afcb030 100644
--- a/bin/pg_repack.c
+++ b/bin/pg_repack.c
@@ -229,7 +229,7 @@ getoid(PGresult *res, int row, int col)
 static bool
 repack_one_database(const char *orderby, const char *table, char *errbuf, size_t errsize)
 {
-	bool			ret = true;
+	bool			ret = false;
 	PGresult	   *res;
 	int				i;
 	int				num;
@@ -239,6 +239,43 @@ repack_one_database(const char *orderby, const char *table, char *errbuf, size_t
 
 	reconnect(ERROR);
 
+	/* Query the extension version. Exit if no match */
+	res = execute_elevel("select repack.version()", 0, NULL, DEBUG2);
+	if (PQresultStatus(res) == PGRES_TUPLES_OK)
+	{
+		const char	   *libver;
+		char			buf[64];
+
+		/* the string is something like "pg_repack 1.1.7" */
+		libver = getstr(res, 0, 0);
+		snprintf(buf, sizeof(buf), "%s %s", PROGRAM_NAME, PROGRAM_VERSION);
+		if (0 != strcmp(buf, libver))
+		{
+			if (errbuf)
+				snprintf(errbuf, errsize,
+					"program '%s' does not match database library '%s'",
+					buf, libver);
+			goto cleanup;
+		}
+	}
+	else
+	{
+		if (sqlstate_equals(res, SQLSTATE_INVALID_SCHEMA_NAME))
+		{
+			/* Schema repack does not exist. Skip the database. */
+			if (errbuf)
+				snprintf(errbuf, errsize,
+					"%s is not installed in the database", PROGRAM_NAME);
+		}
+		else
+		{
+			/* Return the error message otherwise */
+			if (errbuf)
+				snprintf(errbuf, errsize, "%s", PQerrorMessage(connection));
+		}
+		goto cleanup;
+	}
+
 	/* Disable statement timeout. */
 	command("SET statement_timeout = 0", 0, NULL);
 
@@ -346,6 +383,7 @@ repack_one_database(const char *orderby, const char *table, char *errbuf, size_t
 
 		repack_one_table(&table, orderby);
 	}
+	ret = true;
 
 cleanup:
 	PQclear(res);
diff --git a/doc/pg_repack.rst b/doc/pg_repack.rst
index 7820593..6682f3c 100644
--- a/doc/pg_repack.rst
+++ b/doc/pg_repack.rst
@@ -281,6 +281,15 @@ ERROR: pg_repack is not installed
 
     Do register pg_repack to the database.
 
+ERROR: program 'pg_repack V1' does not match database library 'pg_repack V2'
+    There is a mismatch between the ``pg_repack`` binary and the database
+    library (``.so`` or ``.dll``).
+
+    The mismatch could be due to the wrong binary in the ``$PATH`` or the
+    wrong database being addressed. Check the program directory and the
+    database; if they are what expected you may need to repeat pg_repack
+    installation.
+
 ERROR: relation "table" has no primary key
     The target table doesn't have PRIMARY KEY.