Documentation
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Overview ¶
Package event aggregates MySQL log and Perfomance Schema events into query classes and calculates basic statistics for class metrics like max Query_time. Event aggregation into query classes is the foundation of MySQL log file and Performance Schema analysis.
An event is a query like "SELECT col FROM t WHERE id = 1", some metrics like Query_time (slow log) or SUM_TIMER_WAIT (Performance Schema), and other metadata like default database, timestamp, etc. Events are grouped into query classes by fingerprinting the query (see percona.com/go-mysql/query/), then checksumming the fingerprint which yields a 16-character hexadecimal value called the class ID. As events are added to a class, metric values are saved. When there are no more events, the class is finalized to compute the statistics for all metrics.
There are two types of classes: global and per-query. A global class contains all events added to it, regardless of fingerprint or class ID. This is used, for example, to aggregate all events in a log file. A per-query class contains events with the same fingerprint and class ID. This is only enforced by convention, so be careful not to mix events from different classes. This is used, for example, to aggregate unique queries in a log file, then sort the classes by some metric, like max Query_time, to find the slowest query relative to a global class for the same set of events.
Index ¶
Constants ¶
const ( // MaxExampleBytes defines to how many bytes truncate a query. MaxExampleBytes = 2 * 1024 * 10 // TruncatedExampleSuffix is added to truncated query. TruncatedExampleSuffix = "..." )
Variables ¶
This section is empty.
Functions ¶
func Float64Value ¶
Float64Value returns the value of the float64 pointer passed in or 0 if the pointer is nil.
func Uint64Value ¶
Uint64Value returns the value of the uint64 pointer passed in or 0 if the pointer is nil.
Types ¶
type Aggregator ¶
type Aggregator struct {
// contains filtered or unexported fields
}
An Aggregator groups events by class ID. When there are no more events, a call to Finalize computes all metric statistics and returns a Result.
func NewAggregator ¶
func NewAggregator(samples bool, utcOffset time.Duration, outlierTime float64) *Aggregator
NewAggregator returns a new Aggregator. outlierTime is https://www.percona.com/doc/percona-server/5.5/diagnostics/slow_extended_55.html#slow_query_log_always_write_time
func (*Aggregator) AddEvent ¶
func (a *Aggregator) AddEvent(event *log.Event, id, user, host, db, server, fingerprint string)
AddEvent adds the event to the aggregator, automatically creating new classes as needed.
func (*Aggregator) Finalize ¶
func (a *Aggregator) Finalize() Result
Finalize calculates all metric statistics and returns a Result. Call this function when done adding events to the aggregator.
type BoolStats ¶
type BoolStats struct {
Cnt uint64
Sum uint64 // %true = Sum/Cnt
// contains filtered or unexported fields
}
BoolStats are boolean-based metrics like QC_Hit and Filesort.
type Class ¶
type Class struct {
Id string // 32-character hex checksum of fingerprint
User string
Host string
Db string
Server string
LabelsKey []string
LabelsValue []string
Fingerprint string // canonical form of query: values replaced with "?"
Metrics *Metrics // statistics for each metric, e.g. max Query_time
TotalQueries uint // total number of queries in class
UniqueQueries uint // unique number of queries in class
Example *Example `json:",omitempty"` // sample query with max Query_time
NumQueriesWithErrors float32
ErrorsCode []uint64
ErrorsCount []uint64
// contains filtered or unexported fields
}
A Class represents all events with the same fingerprint and class ID. This is only enforced by convention, so be careful not to mix events from different classes.
func NewClass ¶
NewClass returns a new Class for the class ID and fingerprint. If sample is true, the query with the greatest Query_time is saved.
func (*Class) AddClass ¶
AddClass adds a Class to the current class. This is used with Performance Schema which returns pre-aggregated classes instead of events.
type Example ¶
type Example struct {
QueryTime float64 // Query_time
Db string // Schema: <db> or USE <db>
Query string // truncated to MaxExampleBytes
Size int `json:",omitempty"` // Original size of query.
Ts string `json:",omitempty"` // in MySQL time zone
}
A Example is a real query and its database, timestamp, and Query_time. If the query is larger than MaxExampleBytes, it is truncated and TruncatedExampleSuffix is appended.
type Metrics ¶
type Metrics struct {
TimeMetrics map[string]*TimeStats `json:",omitempty"`
NumberMetrics map[string]*NumberStats `json:",omitempty"`
BoolMetrics map[string]*BoolStats `json:",omitempty"`
}
Metrics encapsulate the metrics of an event like Query_time and Rows_sent.
func NewMetrics ¶
func NewMetrics() *Metrics
NewMetrics returns a pointer to an initialized Metrics structure.
type NumberStats ¶
type NumberStats struct {
Cnt uint64
Sum uint64
Min *uint64 `json:",omitempty"`
P99 *uint64 `json:",omitempty"` // 99th percentile
Max *uint64 `json:",omitempty"`
// contains filtered or unexported fields
}
NumberStats are integer-based metrics like Rows_sent and Merge_passes.
Source Files