[1899] Add a unique constraint to nsec3 table

This is to check that only one NSEC3 RR exists per owner name in a
zone.  The code to fix #1899 would depend on this assertion.

src/bin/dbutil/dbutil.py.in

@@ -193,10 +193,19 @@ UPGRADES = [
             "ALTER TABLE schema_version " +
                 "ADD COLUMN minor INTEGER NOT NULL DEFAULT 0"
         ]
+     },
+
+    {'from': (2, 0), 'to': (2, 1),
+     'statements': [
+            # Enforce that only one NSEC3 RR exists for an owner name in
+            # the zone.
+            "CREATE UNIQUE INDEX nsec3_by_zoneid_and_owner ON nsec3 " +
+                "(zone_id, owner)"
+        ]
     }
 
 # To extend this, leave the above statements in place and add another
-# dictionary to the list.  The "from" version should be (2, 0), the "to"
+# dictionary to the list.  The "from" version should be (2, 1), the "to"
 # version whatever the version the update is to, and the SQL statements are
 # the statements required to perform the upgrade.  This way, the upgrade
 # program will be able to upgrade both a V1.0 and a V2.0 database.

src/bin/dbutil/tests/dbutil_test.sh.in

@@ -165,7 +165,7 @@ upgrade_ok_test() {
     if [ $? -eq 0 ]
     then
         # Compare schema with the reference
-        get_schema $testdata/v2_0.sqlite3
+        get_schema $testdata/v2_1.sqlite3
         expected_schema=$db_schema
         get_schema $tempfile
         actual_schema=$db_schema
@@ -177,7 +177,7 @@ upgrade_ok_test() {
         fi
 
         # Check the version is set correctly
-        check_version $tempfile "V2.0"
+        check_version $tempfile "V2.1"
 
         # Check that a backup was made
         check_backup $1 $2
@@ -449,7 +449,7 @@ copy_file $testdata/old_v1.sqlite3 $tempfile
 Yes
 .
 passzero $?
-check_version $tempfile "V2.0"
+check_version $tempfile "V2.1"
 rm -f $tempfile $backupfile
 
 echo "13.4 Interactive prompt - no"

src/bin/dbutil/tests/testdata/Makefile.am

@@ -10,3 +10,4 @@ EXTRA_DIST += old_v1.sqlite3
 EXTRA_DIST += README
 EXTRA_DIST += too_many_version.sqlite3
 EXTRA_DIST += v2_0.sqlite3
+EXTRA_DIST += v2_1.sqlite3

src/lib/datasrc/sqlite3_accessor.cc

@@ -42,7 +42,7 @@ namespace {
 // program may not be taking advantage of features (possibly performance
 // improvements) added to the database.
 const int SQLITE_SCHEMA_MAJOR_VERSION = 2;
-const int SQLITE_SCHEMA_MINOR_VERSION = 0;
+const int SQLITE_SCHEMA_MINOR_VERSION = 1;
 }
 
 namespace isc {
@@ -325,7 +325,7 @@ public:
 const char* const SCHEMA_LIST[] = {
     "CREATE TABLE schema_version (version INTEGER NOT NULL, "
         "minor INTEGER NOT NULL DEFAULT 0)",
-    "INSERT INTO schema_version VALUES (2, 0)",
+    "INSERT INTO schema_version VALUES (2, 1)",
     "CREATE TABLE zones (id INTEGER PRIMARY KEY, "
     "name TEXT NOT NULL COLLATE NOCASE, "
     "rdclass TEXT NOT NULL COLLATE NOCASE DEFAULT 'IN', "
@@ -351,6 +351,8 @@ const char* const SCHEMA_LIST[] = {
         "ttl INTEGER NOT NULL, rdtype TEXT NOT NULL COLLATE NOCASE, "
         "rdata TEXT NOT NULL)",
     "CREATE INDEX nsec3_byhash ON nsec3 (hash)",
+    // Enforce that only one NSEC3 RR exists for an owner name in the zone.
+    "CREATE UNIQUE INDEX nsec3_by_zoneid_and_owner ON nsec3 (zone_id, owner)",
     "CREATE TABLE diffs (id INTEGER PRIMARY KEY, "
         "zone_id INTEGER NOT NULL, "
         "version INTEGER NOT NULL, "

src/lib/python/isc/datasrc/sqlite3_ds.py

@@ -25,7 +25,7 @@ RR_RDATA_INDEX = 7
 
 # Current major and minor versions of schema
 SCHEMA_MAJOR_VERSION = 2
-SCHEMA_MINOR_VERSION = 0
+SCHEMA_MINOR_VERSION = 1
 
 class Sqlite3DSError(Exception):
     """ Define exceptions."""
@@ -81,6 +81,9 @@ def create(cur):
                     rdtype TEXT NOT NULL COLLATE NOCASE,
                     rdata TEXT NOT NULL)""")
         cur.execute("CREATE INDEX nsec3_byhash ON nsec3 (hash)")
+        # Enforce that only one NSEC3 RR exists for an owner name in the zone.
+        cur.execute("""CREATE UNIQUE INDEX nsec3_by_zoneid_and_owner ON nsec3
+                        (zone_id, owner)""");
         cur.execute("""CREATE TABLE diffs (id INTEGER PRIMARY KEY,
                     zone_id INTEGER NOT NULL,
                     version INTEGER NOT NULL,