【版本】5.2.1
dashboard查看select的慢SQL有大量 mysql.stats_histograms where table_id = 296的慢SQL，时间主要是Cop_backoff_txnNotFound
Time: 2021-09-14T01:05:29.175239735+08:00
Txn_start_ts: 427701757281566748
Query_time: 5.149068083
Parse_time: 0
Compile_time: 0.000406489
Rewrite_time: 0.00010761
Optimize_time: 0.000176125
Wait_TS: 0.000005566
Cop_time: 5.148211751 Process_time: 0.004 Wait_time: 0.003 Backoff_time: 5.01 Request_count: 3 Process_keys: 184 Total_keys: 1278 Rocksdb_delete_skipped_count: 191 Rocksdb_key_skipped_count: 2154 Rocksdb_block_cache_hit_count: 409 Rocksdb_block_read_count: 2 Rocksdb_block_read_byte: 130981
Index_names: [stats_histograms:tbl]
Is_internal: true
Digest: 1772d6feeaef69bc4752bc98819036e7f725f5e752a8756f269ddcdfe147b24a
Stats: stats_histograms:425945805994328068
Num_cop_tasks: 3
Cop_proc_avg: 0.001333333 Cop_proc_p90: 0.003 Cop_proc_max: 0.003 Cop_proc_addr: 10.161.67.80:20160
Cop_wait_avg: 0.001 Cop_wait_p90: 0.003 Cop_wait_max: 0.003 Cop_wait_addr: 10.161.67.84:20160
Cop_backoff_txnNotFound_total_times: 17 Cop_backoff_txnNotFound_total_time: 5.01 Cop_backoff_txnNotFound_max_time: 5.01 Cop_backoff_txnNotFound_max_addr: 10.161.67.80:20160 Cop_backoff_txnNotFound_avg_time: 5.01 Cop_backoff_txnNotFound_p90_time: 5.01
Mem_max: 37680
Prepared: false
Plan_from_cache: false
Plan_from_binding: false
Has_more_results: false
KV_total: 0.135352848
PD_total: 0.000006281
Backoff_total: 5.01
Write_sql_response_total: 0
Succ: true
Plan: tidb_decode_plan(‘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’)
Plan_digest: 6fa677a433652b855df12b5c197df0c72fd5a4bc516e08a2cd4f0ea160492a3c
select table_id, is_index, hist_id, distinct_count, version, null_count, tot_col_size, stats_ver, flag, correlation, last_analyze_pos from mysql.stats_histograms where table_id = 296;