fix the problem that expired data was not recycled timely due to slow…

… gc speed (pingcap#4224)

close pingcap#4146

dbms/src/Interpreters/Settings.h

@@ -258,8 +258,8 @@ struct Settings
     M(SettingUInt64, dt_segment_delta_small_column_file_size, 8388608, "Determine whether a column file in delta is small or not. 8MB by default.")                                                                                     \
     M(SettingUInt64, dt_segment_stable_pack_rows, DEFAULT_MERGE_BLOCK_SIZE, "Expected stable pack rows in DeltaTree Engine.")                                                                                                           \
     M(SettingFloat, dt_segment_wait_duration_factor, 1, "The factor of wait duration in a write stall.")                                                                                                                                \
-    M(SettingUInt64, dt_bg_gc_check_interval, 600, "Background gc thread check interval, the unit is second.")                                                                                                                          \
-    M(SettingInt64, dt_bg_gc_max_segments_to_check_every_round, 15, "Max segments to check in every gc round, value less than or equal to 0 means gc no segments.")                                                                     \
+    M(SettingUInt64, dt_bg_gc_check_interval, 5, "Background gc thread check interval, the unit is second.")                                                                                                                          \
+    M(SettingInt64, dt_bg_gc_max_segments_to_check_every_round, 100, "Max segments to check in every gc round, value less than or equal to 0 means gc no segments.")                                                                     \
     M(SettingFloat, dt_bg_gc_ratio_threhold_to_trigger_gc, 1.2, "Trigger segment's gc when the ratio of invalid version exceed this threhold. Values smaller than or equal to 1.0 means gc all "                                        \
                                                                 "segments")                                                                                                                                                             \
     M(SettingFloat, dt_bg_gc_delta_delete_ratio_to_trigger_gc, 0.3, "Trigger segment's gc when the ratio of delta delete range to stable exceeds this ratio.")                                                                          \