MM-10020: avoid duplicating unique indexes (#8587)

* unit test TestGet(Search)Replica

This adds partial, testing-focused support for SQLite, as well as removing
some translated log messages that required initializing i18n just for
testing.

* avoid returning master twice when no replicas are configured

* remove duplicate indexes

* unit test GetAllConns

vendor/github.com/mattn/go-sqlite3/sqlite3_load_extension.go

@@ -0,0 +1,69 @@
+// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+// +build !sqlite_omit_load_extension
+
+package sqlite3
+
+/*
+#ifndef USE_LIBSQLITE3
+#include <sqlite3-binding.h>
+#else
+#include <sqlite3.h>
+#endif
+#include <stdlib.h>
+*/
+import "C"
+import (
+	"errors"
+	"unsafe"
+)
+
+func (c *SQLiteConn) loadExtensions(extensions []string) error {
+	rv := C.sqlite3_enable_load_extension(c.db, 1)
+	if rv != C.SQLITE_OK {
+		return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+	}
+
+	for _, extension := range extensions {
+		cext := C.CString(extension)
+		defer C.free(unsafe.Pointer(cext))
+		rv = C.sqlite3_load_extension(c.db, cext, nil, nil)
+		if rv != C.SQLITE_OK {
+			C.sqlite3_enable_load_extension(c.db, 0)
+			return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+		}
+	}
+
+	rv = C.sqlite3_enable_load_extension(c.db, 0)
+	if rv != C.SQLITE_OK {
+		return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+	}
+	return nil
+}
+
+// LoadExtension load the sqlite3 extension.
+func (c *SQLiteConn) LoadExtension(lib string, entry string) error {
+	rv := C.sqlite3_enable_load_extension(c.db, 1)
+	if rv != C.SQLITE_OK {
+		return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+	}
+
+	clib := C.CString(lib)
+	defer C.free(unsafe.Pointer(clib))
+	centry := C.CString(entry)
+	defer C.free(unsafe.Pointer(centry))
+
+	rv = C.sqlite3_load_extension(c.db, clib, centry, nil)
+	if rv != C.SQLITE_OK {
+		return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+	}
+
+	rv = C.sqlite3_enable_load_extension(c.db, 0)
+	if rv != C.SQLITE_OK {
+		return errors.New(C.GoString(C.sqlite3_errmsg(c.db)))
+	}
+
+	return nil
+}