add force priority config (#7777)

config/config.go

@@ -157,6 +157,7 @@ type Performance struct {
 	FeedbackProbability float64 `toml:"feedback-probability" json:"feedback-probability"`
 	QueryFeedbackLimit  uint    `toml:"query-feedback-limit" json:"query-feedback-limit"`
 	PseudoEstimateRatio float64 `toml:"pseudo-estimate-ratio" json:"pseudo-estimate-ratio"`
+	ForcePriority       string  `toml:"force-priority" json:"force-priority"`
 }
 
 // XProtocol is the XProtocol section of the config.
@@ -290,6 +291,7 @@ var defaultConf = Config{
 		FeedbackProbability: 0.05,
 		QueryFeedbackLimit:  1024,
 		PseudoEstimateRatio: 0.8,
+		ForcePriority:       "NO_PRIORITY",
 	},
 	XProtocol: XProtocol{
 		XHost: "",

config/config.toml.example

@@ -147,6 +147,10 @@ query-feedback-limit = 1024
 # row count in statistics of a table is greater than it.
 pseudo-estimate-ratio = 0.8
 
+# Force the priority of all statements in a specified priority.
+# The value could be "NO_PRIORITY", "LOW_PRIORITY", "HIGH_PRIORITY" or "DELAYED".
+force-priority = "NO_PRIORITY"
+
 [proxy-protocol]
 # PROXY protocol acceptable client networks.
 # Empty string means disable PROXY protocol, * means all networks.

tidb-server/main.go

@@ -31,6 +31,7 @@ import (
 	"github.com/pingcap/tidb/domain"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/metrics"
+	"github.com/pingcap/tidb/mysql"
 	plannercore "github.com/pingcap/tidb/planner/core"
 	"github.com/pingcap/tidb/privilege/privileges"
 	"github.com/pingcap/tidb/server"
@@ -387,6 +388,7 @@ func setGlobalVars() {
 	ddl.EnableSplitTableRegion = cfg.SplitTable
 	plannercore.AllowCartesianProduct = cfg.Performance.CrossJoin
 	privileges.SkipWithGrant = cfg.Security.SkipGrantTable
+	variable.ForcePriority = int32(mysql.Str2Priority(cfg.Performance.ForcePriority))
 
 	variable.SysVars[variable.TIDBMemQuotaQuery].Value = strconv.FormatInt(cfg.MemQuotaQuery, 10)
 	variable.SysVars["lower_case_table_names"].Value = strconv.Itoa(cfg.LowerCaseTableNames)