improved trigger/sp handling of database versioning

- skip dbsv-update if triggers/sp are not installed (yet)
- added safeguard against downgrading to old trigger/sp versions

bin/dbsv-update.php

@@ -22,10 +22,24 @@
 	require_once($opt['rootpath'] . 'lib2/cli.inc.php');
 
 	if (!sql_field_exists('cache_attrib','gc_id'))
-		die("\n
-	       ERROR: Database structure too old. You must first do a manual update
-				 up to commit 467aae4 (March 27, 2013) to enable automatic updates.
-				 See htdocs/doc/sql/db-changes.txt.\n");
+	{
+		die(
+			"  ERROR: Database structure too old. You must first do a manual update\n" .
+			"  up to commit 467aae4 (March 27, 2013) to enable automatic updates.\n" .
+			"  See htdocs/doc/sql/db-changes.txt.\n");
+		// Do not continue with dbupdate.php, because the current data.sql and
+		// maintain.php will not fit either.
+	}
+
+	if (!sql_function_exists('distance') || !sql_procedure_exists('sp_touch_cache'))
+	{
+		// We need a consistent starting point including triggers & functions, and it's
+		// safer not to decide HERE which trigger version to install.
+		echo "Triggers / DB functions are not installed (yet) - skipping DB versioning.\n";
+		exit;
+			// continue with dbupdate.php if called from there and let's hope
+			// maintain.php matches the installed tables' DB version ...
+	}
 
 	$db_version = max(99, sql_value("SELECT `value` FROM `sysconfig` WHERE `name`='db_version'",99));
 
@@ -59,15 +73,27 @@
 	{
 		global $opt, $db_version;
 
-		$syncfile = $opt['rootpath'] . 'cache2/dbsv-running';
-		file_put_contents($syncfile,'dbsv is running');
+		// For the case we re-run an old mutation for some accident, we must make
+		// sure that we are not downgrading to an old trigger version (which may be
+		// incompatible with the current database structures.
+		if (sql_function_exists('dbsvTriggerVersion'))
+			$trigger_version = sql_value('SELECT dbsvTriggerVersion()',0);
+		else
+			$trigger_version = 0;
 
-		system('php ' . $opt['rootpath'] . 'doc/sql/stored-proc/maintain.php --dbsv '.$db_version.' --flush');
-
-		if (file_exists($syncfile))
+		if ($trigger_version < $db_version)
 		{
-			die("\nmaintain.php was not properly executed\n");
-			unlink($syncfile);
+			$syncfile = $opt['rootpath'] . 'cache2/dbsv-running';
+			file_put_contents($syncfile,'dbsv is running');
+
+			system('php ' . $opt['rootpath'] . 'doc/sql/stored-proc/maintain.php --dbsv '.$db_version.' --flush');
+				// This will also update dbsvTriggerVersion.
+
+			if (file_exists($syncfile))
+			{
+				die("\nmaintain.php was not properly executed\n");
+				unlink($syncfile);
+			}
 		}
 	}
 
@@ -274,8 +300,23 @@
 			sql("ALTER TABLE `caches` ADD INDEX `wp_gc_maintained` (`wp_gc_maintained`)");
 	}
 
-	function dbv_113()  // preventive trigger update
+	function dbv_113()  // preventive, initial trigger update
 	{
+		// The if-condition ensures that we will not downgrade to an old trigger
+		// version for the case this function is re-run by some accident.
+		// For future trigger updates, this will be ensured by the version
+		// number returned by dbsvTriggerVersion().
+
+		if (!sql_function_exists('dbsvTriggerVersion'))
+			update_triggers();
+	}
+
+	function dbv_114()  // add dbsvTriggerVersion
+	{
+		// dbsvTriggerVersion was introduced AFTER defining mutation #113 (it was
+		// inserted there later). So we need to additionally install it on installations
+		// which already updated to v113:
+
 		update_triggers();
 	}
 

htdocs/doc/sql/stored-proc/maintain-113.inc.php

@@ -1745,4 +1745,13 @@
 						UPDATE caches SET meta_last_modified=NOW() WHERE caches.wp_oc=OLD.wp;
 					END;");
 
+	// Update trigger version.
+	// Keep this at the end of this file.
+	sql_dropFunction('dbsvTriggerVersion');
+	$db_version = sqlValue("SELECT `value` FROM `sysconfig` WHERE `name`='db_version'", 0);
+	sql("
+		CREATE FUNCTION `dbsvTriggerVersion` () RETURNS INT
+		RETURN '&1'",
+		$db_version);
+
 ?>

htdocs/doc/sql/stored-proc/maintain-114.inc.php

@@ -0,0 +1,19 @@
+<?php
+ /***************************************************************************
+
+		Unicode Reminder メモ
+
+		initialize trigger version function
+
+	***************************************************************************/
+
+	// We run this via maintain.php instead of dbsv-update.php because the
+	// latter one has no sufficient privileges yet for updating functions
+	// (should be changed / may have been changed when you are reading this.)
+
+	sql_dropFunction('dbsvTriggerVersion');
+	sql("
+		CREATE FUNCTION `dbsvTriggerVersion` () RETURNS INT
+		RETURN 114");
+
+?>

htdocs/doc/sql/stored-proc/maintain-current.inc.php

@@ -1739,4 +1739,14 @@
 						UPDATE caches SET meta_last_modified=NOW() WHERE caches.wp_oc=OLD.wp;
 					END;");
 
-?>
+
+	// Update trigger version function.
+	// Keep this at the end of this file.
+	sql_dropFunction('dbsvTriggerVersion');
+	$db_version = sqlValue("SELECT `value` FROM `sysconfig` WHERE `name`='db_version'", 0);
+	sql("
+		CREATE FUNCTION `dbsvTriggerVersion` () RETURNS INT
+		RETURN '&1'",
+		$db_version);
+
+?>

htdocs/lib2/db.inc.php

@@ -1089,22 +1089,6 @@
 		fclose($f);
 	}
 
-	function sql_dropFunction($name)
-	{
-	  global $dbname;
-
-		$rs = sql("SHOW FUNCTION STATUS LIKE '&1'", $name);
-		while ($r = sql_fetch_assoc($rs))
-		{
-			if ($r['Db'] == $dbname && $r['Name'] == $name && $r['Type'] == 'FUNCTION')
-			{
-				sql('DROP FUNCTION `&1`', $name);
-				return;
-			}
-		}
-		sql_free_result($rs);
-	}
-
 	// test if a database table exists
 	function sql_table_exists($table)
 	{
@@ -1150,4 +1134,43 @@
 										 0, $opt['db']['placeholder']['db'], $table, $index) > 0;
 	}
 
+	// test if a function or procedure exists
+	function sql_fp_exists($type, $name)
+	{
+		global $opt;
+
+		$rs = sql("SHOW $type STATUS LIKE '&1'", $name);
+		$r = sql_fetch_assoc($rs);
+		sql_free_result($rs);
+
+		return ($r &&
+			      $r['Db'] == $opt['db']['placeholder']['db'] &&
+						$r['Name'] == $name &&
+						$r['Type'] == $type);
+	}
+
+	// test if a function exists
+	function sql_function_exists($name)
+	{
+		return sql_fp_exists('FUNCTION',$name);
+	}
+
+	// delete a function
+	function sql_dropFunction($name)
+	{
+		sql('DROP FUNCTION IF EXISTS `&1`', $name);
+	}
+
+	// test if a procedure exists
+	function sql_procedure_exists($name)
+	{
+		return sql_fp_exists('PROCEDURE',$name);
+	}
+
+	// delete a procedure
+	function sql_dropProcedure($name)
+	{
+		sql('DROP PROCEDURE IF EXISTS `&1`', $name);
+	}
+
 ?>