backup: fix the lost empty database (pingcap#34519)

ref pingcap#33866

br/docker/Dockerfile

@@ -1,5 +1,5 @@
 # For loading data to TiDB
-FROM golang:1.16.4-buster as go-ycsb-builder
+FROM golang:1.18-buster as go-ycsb-builder
 WORKDIR /go/src/github.com/pingcap/
 RUN git clone https://github.com/pingcap/go-ycsb.git --depth=1 && \
     cd go-ycsb && \
@@ -8,7 +8,7 @@ RUN git clone https://github.com/pingcap/go-ycsb.git --depth=1 && \
 # For operating minio S3 compatible storage
 FROM minio/mc as mc-builder
 
-FROM golang:1.16.4-buster
+FROM golang:1.18-buster
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     git \

br/pkg/metautil/metafile.go

@@ -335,7 +335,7 @@ func (reader *MetaReader) ReadSchemasFiles(ctx context.Context, output chan<- *T
 				tableMap[tableInfo.ID] = table
 			} else {
 				// empty database
-				tableMap[0] = table
+				tableMap[dbInfo.ID] = table
 			}
 			return nil
 		})

br/tests/br_backup_empty/run.sh

@@ -16,6 +16,7 @@
 
 set -eu
 DB="$TEST_NAME"
+DB_COUNT=10
 
 # backup empty.
 echo "backup empty cluster start..."
@@ -34,15 +35,23 @@ if [ $? -ne 0 ]; then
 fi
 
 # backup and restore empty tables.
-run_sql "CREATE DATABASE $DB;"
+i=1
+while [ $i -le $DB_COUNT ]; do
+    run_sql "CREATE DATABASE $DB$i;"
+    i=$(($i+1))
+done
+
 echo "backup empty db start..."
 run_br --pd $PD_ADDR backup full -s "local://$TEST_DIR/empty_db"
 if [ $? -ne 0 ]; then
     echo "TEST: [$TEST_NAME] failed on backup empty cluster!"
     exit 1
 fi
 
-run_sql "DROP DATABASE $DB"
+while [ $i -le $DB_COUNT ]; do
+    run_sql "DROP DATABASE $DB$i;"
+    i=$(($i+1))
+done
 
 # restore empty.
 echo "restore empty db start..."
@@ -52,7 +61,7 @@ if [ $? -ne 0 ]; then
     exit 1
 fi
 
-run_sql "CREATE TABLE $DB.usertable1 ( \
+run_sql "CREATE TABLE ${DB}1.usertable1 ( \
   YCSB_KEY varchar(64) NOT NULL, \
   FIELD0 varchar(1) DEFAULT NULL, \
   PRIMARY KEY (YCSB_KEY) \
@@ -61,11 +70,18 @@ run_sql "CREATE TABLE $DB.usertable1 ( \
 echo "backup empty table start..."
 run_br --pd $PD_ADDR backup full -s "local://$TEST_DIR/empty_table"
 
-run_sql "DROP DATABASE $DB;"
+while [ $i -le $DB_COUNT ]; do
+    run_sql "DROP DATABASE $DB$i;"
+    i=$(($i+1))
+done
+
 echo "restore empty table start..."
 run_br --pd $PD_ADDR restore full -s "local://$TEST_DIR/empty_table"
 
 # insert one row to make sure table is restored.
-run_sql "INSERT INTO $DB.usertable1 VALUES (\"a\", \"b\");"
+run_sql "INSERT INTO ${DB}1.usertable1 VALUES (\"a\", \"b\");"
 
-run_sql "DROP DATABASE $DB"
+while [ $i -le $DB_COUNT ]; do
+    run_sql "DROP DATABASE $DB$i;"
+    i=$(($i+1))
+done