EnsureStatsInfoCanBeFound ensure a statement statistic is set in context, if not, copy one from another context, this function is copied from EnsureStatementProfiler.

StatsArrayToJsonString return json arr format example: [1,0,0,0,0] got `[1,0,0,0,0]` [1,2,3,4,5] got `[1,2,3.000,4,5]` [2,1,2,3,4,5] got `[2,3.000,4,5,6.000,7]`.

index: 6.

index: 8, version: 4.

index: 7, version: 4.

index: 5.

index: 4.

raw statistics.

float64 array.

float64 array + plus one elem OutTrafficBytes.

..

..

same value as last variable StatsArrayVersion#.

statistic info of sql.