sessionctx: make tidb_max_chunk_size as a global variable (#6585) (#8333

)
pingcap · Nov 16, 2018 · 34d9050 · 34d9050
1 parent 464a3e6
commit 34d9050
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Showing 4 changed files with 9 additions and 4 deletions.
diff --git a/session/session.go b/session/session.go
@@ -1297,6 +1297,7 @@ const loadCommonGlobalVarsSQL = "select HIGH_PRIORITY * from mysql.global_variab
 	variable.TiDBHashJoinConcurrency + quoteCommaQuote +
 	variable.TiDBDDLReorgWorkerCount + quoteCommaQuote +
 	variable.TiDBDistSQLScanConcurrency + quoteCommaQuote +
+	variable.TiDBMaxChunkSize + quoteCommaQuote +
 	variable.TiDBDisableTxnAutoRetry + "')"
 
 // loadCommonGlobalVariablesIfNeeded loads and applies commonly used global variables for the session.

diff --git a/session/session_test.go b/session/session_test.go
@@ -1650,6 +1650,10 @@ func (s *testSchemaSuite) TestTableReaderChunk(c *C) {
 	s.cluster.SplitTable(s.mvccStore, tbl.Meta().ID, 10)
 
 	tk.Se.GetSessionVars().DistSQLScanConcurrency = 1
+	tk.MustExec("set tidb_max_chunk_size = 2")
+	defer func() {
+		tk.MustExec(fmt.Sprintf("set tidb_max_chunk_size = %d", variable.DefMaxChunkSize))
+	}()
 	rs, err := tk.Exec("select * from chk")
 	c.Assert(err, IsNil)
 	chk := rs.NewChunk()

diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
@@ -626,7 +626,7 @@ var defaultSysVars = []*SysVar{
 	{ScopeSession, TiDBBatchDelete, boolToIntStr(DefBatchDelete)},
 	{ScopeSession, TiDBDMLBatchSize, strconv.Itoa(DefDMLBatchSize)},
 	{ScopeSession, TiDBCurrentTS, strconv.Itoa(DefCurretTS)},
-	{ScopeSession, TiDBMaxChunkSize, strconv.Itoa(DefMaxChunkSize)},
+	{ScopeGlobal | ScopeSession, TiDBMaxChunkSize, strconv.Itoa(DefMaxChunkSize)},
 	{ScopeSession, TIDBMemQuotaQuery, strconv.FormatInt(config.GetGlobalConfig().MemQuotaQuery, 10)},
 	{ScopeSession, TIDBMemQuotaHashJoin, strconv.FormatInt(DefTiDBMemQuotaHashJoin, 10)},
 	{ScopeSession, TIDBMemQuotaMergeJoin, strconv.FormatInt(DefTiDBMemQuotaMergeJoin, 10)},

diff --git a/sessionctx/variable/tidb_vars.go b/sessionctx/variable/tidb_vars.go
@@ -78,9 +78,6 @@ const (
 	// User could change it to a smaller one to avoid breaking the transaction size limitation.
 	TiDBDMLBatchSize = "tidb_dml_batch_size"
 
-	// tidb_max_chunk_capacity is used to control the max chunk size during query execution.
-	TiDBMaxChunkSize = "tidb_max_chunk_size"
-
 	// The following session variables controls the memory quota during query execution.
 	// "tidb_mem_quota_query":				control the memory quota of a query.
 	// "tidb_mem_quota_hashjoin": 			control the memory quota of "HashJoinExec".
@@ -149,6 +146,9 @@ const (
 	// when we need to keep the data output order the same as the order of index data.
 	TiDBIndexSerialScanConcurrency = "tidb_index_serial_scan_concurrency"
 
+	// tidb_max_chunk_capacity is used to control the max chunk size during query execution.
+	TiDBMaxChunkSize = "tidb_max_chunk_size"
+
 	// tidb_skip_utf8_check skips the UTF8 validate process, validate UTF8 has performance cost, if we can make sure
 	// the input string values are valid, we can skip the check.
 	TiDBSkipUTF8Check = "tidb_skip_utf8_check"