infoschema: add plan field to the statement summary tables (#14182)

[sre-bot]

cherry-pick #14182 to release-3.0

conflicting files:
statement_summary.go(undeclared function)
tables_test.go(import error)

---

What problem does this PR solve?

Add plan and plan digest to the statement summary tables.
Same SQLs with different plans are summarized in different records in the tables.
Record the SQL and plan that appear at the first time in each summary, not the last time, to increase performance.

Since same SQL may be split into several records, max-stmt-count should increase.

What is changed and how it works?

Add plan_digest and plan fields.
schema_name + digest + prev_sql_digest + plan_digest are combined as a key of the summary map.
Default value of max-stmt-count is increased to 200.
Record the SQL and plan that appear at the first time in each summary, not the last time.

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

mysql> select * from performance_schema.events_statements_summary_by_digest where plan != ''\G
*************************** 1. row ***************************
       SUMMARY_BEGIN_TIME: 2019-12-22 16:00:00
         SUMMARY_END_TIME: 2019-12-22 16:30:00
                STMT_TYPE: select
              SCHEMA_NAME:
                   DIGEST: ff1ba2b3cf4f7452291642f6399447979825a310ef25a78f01288580f398a3c9
              DIGEST_TEXT: 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 = ?
              TABLE_NAMES: mysql.stats_histograms
              INDEX_NAMES: stats_histograms:tbl
              SAMPLE_USER: NULL
               EXEC_COUNT: 17
              SUM_LATENCY: 17842186
              MAX_LATENCY: 1417064
              MIN_LATENCY: 697887
              AVG_LATENCY: 1049540
        AVG_PARSE_LATENCY: 91016
        MAX_PARSE_LATENCY: 150406
      AVG_COMPILE_LATENCY: 309173
      MAX_COMPILE_LATENCY: 389786
             COP_TASK_NUM: 34
     AVG_COP_PROCESS_TIME: 0
     MAX_COP_PROCESS_TIME: 0
  MAX_COP_PROCESS_ADDRESS: NULL
        AVG_COP_WAIT_TIME: 0
        MAX_COP_WAIT_TIME: 0
     MAX_COP_WAIT_ADDRESS: NULL
         AVG_PROCESS_TIME: 0
         MAX_PROCESS_TIME: 0
            AVG_WAIT_TIME: 0
            MAX_WAIT_TIME: 0
         AVG_BACKOFF_TIME: 0
         MAX_BACKOFF_TIME: 0
           AVG_TOTAL_KEYS: 0
           MAX_TOTAL_KEYS: 0
       AVG_PROCESSED_KEYS: 0
       MAX_PROCESSED_KEYS: 0
        AVG_PREWRITE_TIME: 0
        MAX_PREWRITE_TIME: 0
          AVG_COMMIT_TIME: 0
          MAX_COMMIT_TIME: 0
   AVG_GET_COMMIT_TS_TIME: 0
   MAX_GET_COMMIT_TS_TIME: 0
  AVG_COMMIT_BACKOFF_TIME: 0
  MAX_COMMIT_BACKOFF_TIME: 0
    AVG_RESOLVE_LOCK_TIME: 0
    MAX_RESOLVE_LOCK_TIME: 0
AVG_LOCAL_LATCH_WAIT_TIME: 0
MAX_LOCAL_LATCH_WAIT_TIME: 0
           AVG_WRITE_KEYS: 0
           MAX_WRITE_KEYS: 0
           AVG_WRITE_SIZE: 0
           MAX_WRITE_SIZE: 0
     AVG_PREWRITE_REGIONS: 0
     MAX_PREWRITE_REGIONS: 0
            AVG_TXN_RETRY: 0
            MAX_TXN_RETRY: 0
        SUM_BACKOFF_TIMES: 0
            BACKOFF_TYPES: NULL
                  AVG_MEM: 16672
                  MAX_MEM: 16672
        AVG_AFFECTED_ROWS: 0
               FIRST_SEEN: 2019-12-22 16:18:25
                LAST_SEEN: 2019-12-22 16:19:13
        QUERY_SAMPLE_TEXT: 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 = 43
         PREV_SAMPLE_TEXT:
              PLAN_DIGEST: db05f9e134185031e52539c303d1930de3cf6e5d4881aee7ef97ba87a9a0a6d9
                     PLAN: 	Projection_4    	root	10	mysql.stats_histograms.table_id, mysql.stats_histograms.is_index, mysql.stats_histograms.hist_id, mysql.stats_histograms.distinct_count, mysql.stats_histograms.version, mysql.stats_histograms.null_count, mysql.stats_histograms.tot_col_size, mysql.stats_histograms.stats_ver, mysql.stats_histograms.flag, mysql.stats_histograms.correlation, mysql.stats_histograms.last_analyze_pos
	└─IndexLookUp_10	root	10
	  ├─IndexScan_8 	cop 	10	table:stats_histograms, index:table_id, is_index, hist_id, range:[43,43], keep order:false, stats:pseudo
	  └─TableScan_9 	cop 	10	table:stats_histograms, keep order:false, stats:pseudo

Code changes

• N/A

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release note

• And plan and plan_digest to the statement summary tables.
• Change default value of configuration max-stmt-count in [stmt-summary] to 200.

[sre-bot]

/run-all-tests

[djshow832]

/run-all-tests

[crazycs520]

LGTM

[lonng]

LGTM

[bb7133]

LGTM