sql: add SHOW TRANSACTIONS

Release note (sql change): add the SHOW TRANSACTIONS statement, similar
to SHOW SESSIONS and variants. It shows the currently active
transactions in the node or cluster, and some information about them.

docs/generated/sql/bnf/show_var.bnf

@@ -21,5 +21,6 @@ show_stmt ::=
 	| show_stats_stmt
 	| show_tables_stmt
 	| show_trace_stmt
+	| show_transactions_stmt
 	| show_users_stmt
 	| show_zone_stmt

docs/generated/sql/bnf/stmt_block.bnf

@@ -199,6 +199,7 @@ show_stmt ::=
 	| show_stats_stmt
 	| show_tables_stmt
 	| show_trace_stmt
+	| show_transactions_stmt
 	| show_users_stmt
 	| show_zone_stmt
 
@@ -581,6 +582,10 @@ show_trace_stmt ::=
 	'SHOW' opt_compact 'TRACE' 'FOR' 'SESSION'
 	| 'SHOW' opt_compact 'KV' 'TRACE' 'FOR' 'SESSION'
 
+show_transactions_stmt ::=
+	'SHOW' opt_cluster 'TRANSACTIONS'
+	| 'SHOW' 'ALL' opt_cluster 'TRANSACTIONS'
+
 show_users_stmt ::=
 	'SHOW' 'USERS'
 
@@ -878,6 +883,7 @@ unreserved_keyword ::=
 	| 'TIES'
 	| 'TRACE'
 	| 'TRANSACTION'
+	| 'TRANSACTIONS'
 	| 'TRIGGER'
 	| 'TRUNCATE'
 	| 'TRUSTED'

pkg/sql/delegate/delegate.go

@@ -97,6 +97,9 @@ func TryDelegate(
 	case *tree.ShowTables:
 		return d.delegateShowTables(t)
 
+	case *tree.ShowTransactions:
+		return d.delegateShowTransactions(t)
+
 	case *tree.ShowUsers:
 		return d.delegateShowRoles()
 

pkg/sql/delegate/show_transactions.go

@@ -0,0 +1,41 @@
+// Copyright 2020 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package delegate
+
+import (
+	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
+)
+
+const _ = `
+  id UUID,                 -- the unique ID of the transaction
+  node_id INT,             -- the ID of the node running the transaction
+  session_id STRING,       -- the ID of the session
+  start TIMESTAMP,         -- the start time of the transaction
+  txn_string STRING,       -- the string representation of the transcation
+  application_name STRING, -- the name of the application as per SET application_name
+  num_stmts INT,           -- the number of statements executed so far
+  num_retries INT,         -- the number of times the transaction was restarted
+  num_auto_retries INT     -- the number of times the transaction was automatically restarted
+`
+
+func (d *delegator) delegateShowTransactions(n *tree.ShowTransactions) (tree.Statement, error) {
+	const query = `SELECT node_id, id, application_name, num_stmts, num_retries, num_auto_retries FROM `
+	table := `crdb_internal.node_transactions`
+	if n.Cluster {
+		table = `crdb_internal.cluster_transactions`
+	}
+	var filter string
+	if !n.All {
+		filter = " WHERE application_name NOT LIKE '" + sqlbase.InternalAppNamePrefix + "%'"
+	}
+	return parse(query + table + filter)
+}

pkg/sql/parser/parse_test.go

@@ -2049,6 +2049,8 @@ $function$`,
 
 		{`SHOW SESSIONS`, `SHOW CLUSTER SESSIONS`},
 		{`SHOW ALL SESSIONS`, `SHOW ALL CLUSTER SESSIONS`},
+		{`SHOW TRANSACTIONS`, `SHOW CLUSTER TRANSACTIONS`},
+		{`SHOW ALL TRANSACTIONS`, `SHOW ALL CLUSTER TRANSACTIONS`},
 		{`SHOW QUERIES`, `SHOW CLUSTER QUERIES`},
 		{`SHOW ALL QUERIES`, `SHOW ALL CLUSTER QUERIES`},
 

pkg/sql/parser/sql.y

@@ -631,7 +631,8 @@ func (u *sqlSymUnion) alterTypeAddValuePlacement() *tree.AlterTypeAddValuePlacem
 %token <str> SYMMETRIC SYNTAX SYSTEM SQRT SUBSCRIPTION
 
 %token <str> TABLE TABLES TEMP TEMPLATE TEMPORARY TENANT TESTING_RELOCATE EXPERIMENTAL_RELOCATE TEXT THEN
-%token <str> TIES TIME TIMETZ TIMESTAMP TIMESTAMPTZ TO THROTTLING TRAILING TRACE TRANSACTION TREAT TRIGGER TRIM TRUE
+%token <str> TIES TIME TIMETZ TIMESTAMP TIMESTAMPTZ TO THROTTLING TRAILING TRACE
+%token <str> TRANSACTION TRANSACTIONS TREAT TRIGGER TRIM TRUE
 %token <str> TRUNCATE TRUSTED TYPE
 %token <str> TRACING
 
@@ -830,6 +831,7 @@ func (u *sqlSymUnion) alterTypeAddValuePlacement() *tree.AlterTypeAddValuePlacem
 %type <tree.Statement> show_tables_stmt
 %type <tree.Statement> show_trace_stmt
 %type <tree.Statement> show_transaction_stmt
+%type <tree.Statement> show_transactions_stmt
 %type <tree.Statement> show_users_stmt
 %type <tree.Statement> show_zone_stmt
 
@@ -3861,6 +3863,7 @@ show_stmt:
 | show_tables_stmt          // EXTEND WITH HELP: SHOW TABLES
 | show_trace_stmt           // EXTEND WITH HELP: SHOW TRACE
 | show_transaction_stmt     // EXTEND WITH HELP: SHOW TRANSACTION
+| show_transactions_stmt    // EXTEND WITH HELP: SHOW TRANSACTIONS
 | show_users_stmt           // EXTEND WITH HELP: SHOW USERS
 | show_zone_stmt
 | SHOW error                // SHOW HELP: SHOW
@@ -4293,6 +4296,21 @@ show_tables_stmt:
   }
 | SHOW TABLES error // SHOW HELP: SHOW TABLES
 
+// %Help: SHOW TRANSACTIONS - list open client transactions
+// %Category: Misc
+// %Text: SHOW [ALL] [CLUSTER | LOCAL] TRANSACTIONS
+show_transactions_stmt:
+  SHOW opt_cluster TRANSACTIONS
+  {
+    $$.val = &tree.ShowTransactions{Cluster: $2.bool()}
+  }
+| SHOW opt_cluster TRANSACTIONS error // SHOW HELP: SHOW TRANSACTIONS
+| SHOW ALL opt_cluster TRANSACTIONS
+  {
+    $$.val = &tree.ShowTransactions{All: true, Cluster: $3.bool()}
+  }
+| SHOW ALL opt_cluster TRANSACTIONS error // SHOW HELP: SHOW TRANSACTIONS
+
 with_comment:
   WITH COMMENT { $$.val = true }
 | /* EMPTY */  { $$.val = false }
@@ -10729,6 +10747,7 @@ unreserved_keyword:
 | TIES
 | TRACE
 | TRANSACTION
+| TRANSACTIONS
 | TRIGGER
 | TRUNCATE
 | TRUSTED

pkg/sql/sem/tree/show.go

@@ -310,6 +310,25 @@ func (node *ShowTables) Format(ctx *FmtCtx) {
 	}
 }
 
+// ShowTransactions represents a SHOW TRANSACTIONS statement
+type ShowTransactions struct {
+	All     bool
+	Cluster bool
+}
+
+// Format implements the NodeFormatter interface.
+func (node *ShowTransactions) Format(ctx *FmtCtx) {
+	ctx.WriteString("SHOW ")
+	if node.All {
+		ctx.WriteString("ALL ")
+	}
+	if node.Cluster {
+		ctx.WriteString("CLUSTER TRANSACTIONS")
+	} else {
+		ctx.WriteString("LOCAL TRANSACTIONS")
+	}
+}
+
 // ShowConstraints represents a SHOW CONSTRAINTS statement.
 type ShowConstraints struct {
 	Table *UnresolvedObjectName

pkg/sql/sem/tree/stmt.go

@@ -869,6 +869,12 @@ func (*ShowTables) StatementType() StatementType { return Rows }
 // StatementTag returns a short string identifying the type of statement.
 func (*ShowTables) StatementTag() string { return "SHOW TABLES" }
 
+// StatementType implements the Statement interface
+func (*ShowTransactions) StatementType() StatementType { return Rows }
+
+// StatementTag returns a short string identifying the type of statement.
+func (*ShowTransactions) StatementTag() string { return "SHOW TRANSACTIONS" }
+
 // StatementType implements the Statement interface.
 func (*ShowSchemas) StatementType() StatementType { return Rows }
 
@@ -1027,6 +1033,7 @@ func (n *ShowTableStats) String() string                 { return AsString(n) }
 func (n *ShowTables) String() string                     { return AsString(n) }
 func (n *ShowTraceForSession) String() string            { return AsString(n) }
 func (n *ShowTransactionStatus) String() string          { return AsString(n) }
+func (n *ShowTransactions) String() string               { return AsString(n) }
 func (n *ShowLastQueryStatistics) String() string        { return AsString(n) }
 func (n *ShowUsers) String() string                      { return AsString(n) }
 func (n *ShowVar) String() string                        { return AsString(n) }