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dumpling: fix panic when query result is empty #45201

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merged 1 commit into from
Jul 10, 2023
Merged

dumpling: fix panic when query result is empty #45201

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24 changes: 20 additions & 4 deletions dumpling/export/ir_impl.go
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Original file line number Diff line number Diff line change
Expand Up @@ -210,6 +210,7 @@ func (td *tableData) Start(tctx *tcontext.Context, conn *sql.Conn) error {
if err = rows.Err(); err != nil {
return errors.Annotatef(err, "sql: %s", td.query)
}
td.SQLRowIter = nil
td.rows = rows
if td.needColTypes {
ns, err := rows.Columns()
Expand All @@ -226,17 +227,27 @@ func (td *tableData) Start(tctx *tcontext.Context, conn *sql.Conn) error {
td.colTypes = append(td.colTypes, c.DatabaseTypeName())
}
}
td.SQLRowIter = newRowIter(rows, td.colLen)

return nil
}

func (td *tableData) Rows() SQLRowIter {
// should be initialized lazily since it calls rows.Next() which might close the rows when
// there's nothing to read, causes code which relies on rows not closed to fail.
if td.SQLRowIter == nil {
td.SQLRowIter = newRowIter(td.rows, td.colLen)
}
return td.SQLRowIter
}

func (td *tableData) Close() error {
return td.SQLRowIter.Close()
if td.SQLRowIter != nil {
// will close td.rows internally
return td.SQLRowIter.Close()
} else if td.rows != nil {
return td.rows.Close()
}
return nil
}

func (td *tableData) RawRows() *sql.Rows {
Expand Down Expand Up @@ -351,16 +362,21 @@ func newMultiQueriesChunk(queries []string, colLength int) *multiQueriesChunk {
func (td *multiQueriesChunk) Start(tctx *tcontext.Context, conn *sql.Conn) error {
td.tctx = tctx
td.conn = conn
td.SQLRowIter = newMultiQueryChunkIter(td.tctx, td.conn, td.queries, td.colLen)
return nil
}

func (td *multiQueriesChunk) Rows() SQLRowIter {
if td.SQLRowIter == nil {
td.SQLRowIter = newMultiQueryChunkIter(td.tctx, td.conn, td.queries, td.colLen)
}
return td.SQLRowIter
}

func (td *multiQueriesChunk) Close() error {
return td.SQLRowIter.Close()
if td.SQLRowIter != nil {
return td.SQLRowIter.Close()
}
return nil
}

func (*multiQueriesChunk) RawRows() *sql.Rows {
Expand Down
8 changes: 8 additions & 0 deletions dumpling/tests/basic/run.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -154,3 +154,11 @@ export GO_FAILPOINTS="github.com/pingcap/tidb/dumpling/export/SetIOTotalBytes=re
run_dumpling -B "test_db" -L ${DUMPLING_OUTPUT_DIR}/dumpling.log
cnt=$(grep "IOTotalBytes=" ${DUMPLING_OUTPUT_DIR}/dumpling.log | grep -v "IOTotalBytes=0" | wc -l)
[ "$cnt" -ge 1 ]

export GO_FAILPOINTS=""
export DUMPLING_TEST_PORT=4000
echo "Test for empty query result, should success."
run_sql "drop database if exists test_db;"
run_sql "create database test_db;"
run_sql "create table test_db.test_table (a int primary key);"
run_dumpling --sql "select * from test_db.test_table" --filetype csv > ${DUMPLING_OUTPUT_DIR}/dumpling.log