faster status updates #2615
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faster status updates #2615
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…-server into max/sync-status-updates
zachmu
approved these changes
Aug 1, 2024
sql/core.go
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| @@ -713,7 +713,7 @@ type StatusVariableRegistry interface { | |||
| // SetGlobal sets the global value of the status variable with the given name, returns an error if the variable is SessionOnly scope | |||
| SetGlobal(name string, val interface{}) error | |||
| // IncrementGlobal increments the value of the status variable by the given integer value | |||
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Should document failure behavior, kind of important
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added note about session-only nooping
| v, ok := g.varVals[name] | ||
| if !ok || v.Variable().GetScope() == sql.StatusVariableScope_Session { | ||
| return sql.ErrUnknownSystemVariable.New(name) | ||
| return |
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Appropriate to panic here? Basically always means a bug right?
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The globals list excludes sessionOnly*, so it's only ~297/678 of the total list. So we want to ideally not call this on session only, but noop if we do.
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The query type counters have both scopes unfortunately, so I had to leave those for now
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System variables can be session, global, or both.
sql.IncrementStatusVariableis a helper method that primarily helps the "both" category increment the global and session counters for certain variables.Threads_runningis a global only variable that is incremented/decremented every begin/end query, and gets a lot of traffic. The old code usedsql.IncrementStatusVariableto incrementThreads_running, which was a particularly expensive way to increment a global var because (1) we'd make a new error for every call to the session updater, and (2) the extra map lookup is unnecessary. We don't do the extra map lookup now, and we weren't using the error return so I removed the return variable.Note: this also refactors status variables to be explicitly initializated in the engine
bump/perf here: dolthub/dolt#8189