sql: implement pg_prepared_statements virtual table

Release note (sql change): introduces pg_prepared_statements table for
use

pkg/sql/conn_executor.go

@@ -2342,6 +2342,17 @@ type connExPrepStmtsAccessor struct {
 
 var _ preparedStatementsAccessor = connExPrepStmtsAccessor{}
 
+// List is part of the preparedStatementsAccessor interface.
+func (ps connExPrepStmtsAccessor) List() map[string]*PreparedStatement {
+	// Return a copy of the data, to prevent modification of the map.
+	stmts := ps.ex.extraTxnState.prepStmtsNamespace.prepStmts
+	ret := make(map[string]*PreparedStatement, len(stmts))
+	for key, stmt := range stmts {
+		ret[key] = stmt
+	}
+	return ret
+}
+
 // Get is part of the preparedStatementsAccessor interface.
 func (ps connExPrepStmtsAccessor) Get(name string) (*PreparedStatement, bool) {
 	s, ok := ps.ex.extraTxnState.prepStmtsNamespace.prepStmts[name]

pkg/sql/conn_executor_exec.go

@@ -325,6 +325,7 @@ func (ex *connExecutor) execStmtInOpenState(
 				},
 			},
 			typeHints,
+			PreparedStatementOriginSQL,
 		); err != nil {
 			return makeErrEvent(err)
 		}

pkg/sql/conn_executor_prepare.go

@@ -22,6 +22,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
 	"github.com/cockroachdb/cockroach/pkg/util/fsm"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
 	"github.com/cockroachdb/errors"
 	"github.com/lib/pq/oid"
 )
@@ -49,7 +50,11 @@ func (ex *connExecutor) execPrepare(
 	}
 
 	ps, err := ex.addPreparedStmt(
-		ctx, parseCmd.Name, Statement{Statement: parseCmd.Statement}, parseCmd.TypeHints,
+		ctx,
+		parseCmd.Name,
+		Statement{Statement: parseCmd.Statement},
+		parseCmd.TypeHints,
+		PreparedStatementOriginWire,
 	)
 	if err != nil {
 		return retErr(err)
@@ -87,14 +92,18 @@ func (ex *connExecutor) execPrepare(
 //
 // placeholderHints are used to assist in inferring placeholder types.
 func (ex *connExecutor) addPreparedStmt(
-	ctx context.Context, name string, stmt Statement, placeholderHints tree.PlaceholderTypes,
+	ctx context.Context,
+	name string,
+	stmt Statement,
+	placeholderHints tree.PlaceholderTypes,
+	origin PreparedStatementOrigin,
 ) (*PreparedStatement, error) {
 	if _, ok := ex.extraTxnState.prepStmtsNamespace.prepStmts[name]; ok {
 		panic(fmt.Sprintf("prepared statement already exists: %q", name))
 	}
 
 	// Prepare the query. This completes the typing of placeholders.
-	prepared, err := ex.prepare(ctx, stmt, placeholderHints)
+	prepared, err := ex.prepare(ctx, stmt, placeholderHints, origin)
 	if err != nil {
 		return nil, err
 	}
@@ -114,7 +123,10 @@ func (ex *connExecutor) addPreparedStmt(
 // The PreparedStatement is returned (or nil if there are no results). The
 // returned PreparedStatement needs to be close()d once its no longer in use.
 func (ex *connExecutor) prepare(
-	ctx context.Context, stmt Statement, placeholderHints tree.PlaceholderTypes,
+	ctx context.Context,
+	stmt Statement,
+	placeholderHints tree.PlaceholderTypes,
+	origin PreparedStatementOrigin,
 ) (*PreparedStatement, error) {
 	if placeholderHints == nil {
 		placeholderHints = make(tree.PlaceholderTypes, stmt.NumPlaceholders)
@@ -128,6 +140,9 @@ func (ex *connExecutor) prepare(
 		},
 		memAcc:   ex.sessionMon.MakeBoundAccount(),
 		refCount: 1,
+
+		createdAt: timeutil.Now(),
+		origin:    origin,
 	}
 	// NB: if we start caching the plan, we'll want to keep around the memory
 	// account used for the plan, rather than clearing it.

pkg/sql/logictest/testdata/logic_test/grant_table

@@ -120,6 +120,7 @@ test           pg_catalog          pg_locks                           public   S
 test           pg_catalog          pg_matviews                        public   SELECT
 test           pg_catalog          pg_namespace                       public   SELECT
 test           pg_catalog          pg_operator                        public   SELECT
+test           pg_catalog          pg_prepared_statements             public   SELECT
 test           pg_catalog          pg_prepared_xacts                  public   SELECT
 test           pg_catalog          pg_proc                            public   SELECT
 test           pg_catalog          pg_range                           public   SELECT

pkg/sql/logictest/testdata/logic_test/information_schema

@@ -296,6 +296,7 @@ pg_catalog          pg_locks
 pg_catalog          pg_matviews
 pg_catalog          pg_namespace
 pg_catalog          pg_operator
+pg_catalog          pg_prepared_statements
 pg_catalog          pg_prepared_xacts
 pg_catalog          pg_proc
 pg_catalog          pg_range
@@ -434,6 +435,7 @@ pg_locks
 pg_matviews
 pg_namespace
 pg_operator
+pg_prepared_statements
 pg_prepared_xacts
 pg_proc
 pg_range
@@ -579,6 +581,7 @@ system         pg_catalog          pg_locks                           SYSTEM VIE
 system         pg_catalog          pg_matviews                        SYSTEM VIEW  NO                  1
 system         pg_catalog          pg_namespace                       SYSTEM VIEW  NO                  1
 system         pg_catalog          pg_operator                        SYSTEM VIEW  NO                  1
+system         pg_catalog          pg_prepared_statements             SYSTEM VIEW  NO                  1
 system         pg_catalog          pg_prepared_xacts                  SYSTEM VIEW  NO                  1
 system         pg_catalog          pg_proc                            SYSTEM VIEW  NO                  1
 system         pg_catalog          pg_range                           SYSTEM VIEW  NO                  1
@@ -1380,6 +1383,7 @@ NULL     public   system         pg_catalog          pg_locks
 NULL     public   system         pg_catalog          pg_matviews                        SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_namespace                       SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_operator                        SELECT          NULL          YES
+NULL     public   system         pg_catalog          pg_prepared_statements             SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_prepared_xacts                  SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_proc                            SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_range                           SELECT          NULL          YES
@@ -1671,6 +1675,7 @@ NULL     public   system         pg_catalog          pg_locks
 NULL     public   system         pg_catalog          pg_matviews                        SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_namespace                       SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_operator                        SELECT          NULL          YES
+NULL     public   system         pg_catalog          pg_prepared_statements             SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_prepared_xacts                  SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_proc                            SELECT          NULL          YES
 NULL     public   system         pg_catalog          pg_range                           SELECT          NULL          YES

pkg/sql/logictest/testdata/logic_test/pg_catalog

@@ -44,6 +44,7 @@ pg_locks
 pg_matviews
 pg_namespace
 pg_operator
+pg_prepared_statements
 pg_prepared_xacts
 pg_proc
 pg_range
@@ -117,6 +118,7 @@ pg_locks
 pg_matviews
 pg_namespace
 pg_operator
+pg_prepared_statements
 pg_prepared_xacts
 pg_proc
 pg_range
@@ -1441,26 +1443,27 @@ objoid      classoid    objsubid  description
 4294967211  4294967230  0         available materialized views (empty - feature does not exist)
 4294967210  4294967230  0         available namespaces (incomplete; namespaces and databases are congruent in CockroachDB)
 4294967209  4294967230  0         operators (incomplete)
-4294967208  4294967230  0         prepared transactions (empty - feature does not exist)
-4294967207  4294967230  0         built-in functions (incomplete)
-4294967206  4294967230  0         range types (empty - feature does not exist)
-4294967205  4294967230  0         rewrite rules (empty - feature does not exist)
-4294967204  4294967230  0         database roles
-4294967191  4294967230  0         security labels (empty - feature does not exist)
-4294967203  4294967230  0         security labels (empty)
-4294967202  4294967230  0         sequences (see also information_schema.sequences)
-4294967201  4294967230  0         session variables (incomplete)
-4294967200  4294967230  0         shared dependencies (empty - not implemented)
+4294967208  4294967230  0         prepared statements
+4294967207  4294967230  0         prepared transactions (empty - feature does not exist)
+4294967206  4294967230  0         built-in functions (incomplete)
+4294967205  4294967230  0         range types (empty - feature does not exist)
+4294967204  4294967230  0         rewrite rules (empty - feature does not exist)
+4294967203  4294967230  0         database roles
+4294967190  4294967230  0         security labels (empty - feature does not exist)
+4294967202  4294967230  0         security labels (empty)
+4294967201  4294967230  0         sequences (see also information_schema.sequences)
+4294967200  4294967230  0         session variables (incomplete)
+4294967199  4294967230  0         shared dependencies (empty - not implemented)
 4294967222  4294967230  0         shared object comments
-4294967190  4294967230  0         shared security labels (empty - feature not supported)
-4294967192  4294967230  0         backend access statistics (empty - monitoring works differently in CockroachDB)
-4294967197  4294967230  0         tables summary (see also information_schema.tables, pg_catalog.pg_class)
-4294967196  4294967230  0         available tablespaces (incomplete; concept inapplicable to CockroachDB)
-4294967195  4294967230  0         triggers (empty - feature does not exist)
-4294967194  4294967230  0         scalar types (incomplete)
-4294967199  4294967230  0         database users
-4294967198  4294967230  0         local to remote user mapping (empty - feature does not exist)
-4294967193  4294967230  0         view definitions (incomplete - see also information_schema.views)
+4294967189  4294967230  0         shared security labels (empty - feature not supported)
+4294967191  4294967230  0         backend access statistics (empty - monitoring works differently in CockroachDB)
+4294967196  4294967230  0         tables summary (see also information_schema.tables, pg_catalog.pg_class)
+4294967195  4294967230  0         available tablespaces (incomplete; concept inapplicable to CockroachDB)
+4294967194  4294967230  0         triggers (empty - feature does not exist)
+4294967193  4294967230  0         scalar types (incomplete)
+4294967198  4294967230  0         database users
+4294967197  4294967230  0         local to remote user mapping (empty - feature does not exist)
+4294967192  4294967230  0         view definitions (incomplete - see also information_schema.views)
 
 ## pg_catalog.pg_shdescription
 
@@ -1835,6 +1838,26 @@ SELECT unnest((SELECT proargtypes FROM pg_proc WHERE proname='split_part'));
 25
 20
 
+subtest pg_catalog.pg_prepare_statement
+
+statement ok
+CREATE TABLE types(a timestamptz, b integer)
+
+statement ok
+PREPARE test_insert_statement (integer, timestamptz) AS INSERT INTO types VALUES ($2, $1)
+
+statement ok
+PREPARE test_select_statement AS SELECT * FROM types
+
+query TTTB
+select name, statement, parameter_types, from_sql from pg_prepared_statements ORDER BY 1
+----
+test_insert_statement  PREPARE test_insert_statement (int, timestamptz) AS INSERT INTO types VALUES ($2, $1)  {bigint,"'timestamp with time zone'"}  true
+test_select_statement  PREPARE test_select_statement AS SELECT * FROM types                                   {}                                     true
+
+statement ok
+DROP TABLE types;
+
 ## TODO(masha): #16769
 #statement ok
 #CREATE TABLE types(a int8, b int2);

pkg/sql/pg_catalog.go

@@ -18,6 +18,7 @@ import (
 	"hash"
 	"hash/fnv"
 	"strings"
+	"time"
 	"unicode"
 
 	"github.com/cockroachdb/cockroach/pkg/keys"
@@ -214,6 +215,7 @@ var pgCatalog = virtualSchema{
 		sqlbase.PgCatalogMatViewsTableID:            pgCatalogMatViewsTable,
 		sqlbase.PgCatalogNamespaceTableID:           pgCatalogNamespaceTable,
 		sqlbase.PgCatalogOperatorTableID:            pgCatalogOperatorTable,
+		sqlbase.PgCatalogPreparedStatementsTableID:  pgCatalogPreparedStatementsTable,
 		sqlbase.PgCatalogPreparedXactsTableID:       pgCatalogPreparedXactsTable,
 		sqlbase.PgCatalogProcTableID:                pgCatalogProcTable,
 		sqlbase.PgCatalogRangeTableID:               pgCatalogRangeTable,
@@ -1758,6 +1760,63 @@ CREATE TABLE pg_catalog.pg_prepared_xacts (
 	},
 }
 
+// pgCatalogPreparedStatementsTable implements the pg_prepared_statements table.
+// The statement field differs in that it uses the parsed version
+// of the PREPARE statement.
+// The parameter_types field differs from postgres as the type names in
+// cockroach are slightly different.
+var pgCatalogPreparedStatementsTable = virtualSchemaTable{
+	comment: `prepared statements
+https://www.postgresql.org/docs/9.6/view-pg-prepared-statements.html`,
+	schema: `
+CREATE TABLE pg_catalog.pg_prepared_statements (
+	name TEXT,
+	statement TEXT,
+	prepare_time TIMESTAMPTZ,
+	parameter_types REGTYPE[],
+	from_sql boolean
+)`,
+	populate: func(ctx context.Context, p *planner, dbContext *DatabaseDescriptor, addRow func(...tree.Datum) error) error {
+		for name, stmt := range p.preparedStatements.List() {
+			placeholderTypes := stmt.PrepareMetadata.PlaceholderTypesInfo.Types
+			paramTypes := tree.NewDArray(types.RegType)
+			paramTypes.Array = make(tree.Datums, len(placeholderTypes))
+			paramNames := make([]string, len(placeholderTypes))
+
+			for i, placeholderType := range placeholderTypes {
+				paramTypes.Array[i] = tree.NewDOidWithName(
+					tree.DInt(placeholderType.Oid()),
+					placeholderType,
+					placeholderType.SQLStandardName(),
+				)
+				paramNames[i] = placeholderType.Name()
+			}
+
+			// Only append arguments to string if required.
+			argumentsStr := ""
+			if len(paramNames) > 0 {
+				argumentsStr = fmt.Sprintf(" (%s)", strings.Join(paramNames, ", "))
+			}
+
+			fromSQL := tree.DBoolFalse
+			if stmt.origin == PreparedStatementOriginSQL {
+				fromSQL = tree.DBoolTrue
+			}
+
+			if err := addRow(
+				tree.NewDString(name),
+				tree.NewDString(fmt.Sprintf("PREPARE %s%s AS %s", name, argumentsStr, stmt.SQL)),
+				tree.MakeDTimestampTZ(stmt.createdAt, time.Microsecond),
+				paramTypes,
+				fromSQL,
+			); err != nil {
+				return err
+			}
+		}
+		return nil
+	},
+}
+
 var pgCatalogProcTable = virtualSchemaTable{
 	comment: `built-in functions (incomplete)
 https://www.postgresql.org/docs/9.5/catalog-pg-proc.html`,

pkg/sql/prepared_stmt.go

@@ -12,6 +12,7 @@ package sql
 
 import (
 	"context"
+	"time"
 	"unsafe"
 
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/memo"
@@ -22,6 +23,19 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/mon"
 )
 
+// PreparedStatementOrigin is an enum representing the source of where
+// the prepare statement was made.
+type PreparedStatementOrigin int
+
+const (
+	// PreparedStatementOriginWire signifies the prepared statement was made
+	// over the wire.
+	PreparedStatementOriginWire PreparedStatementOrigin = iota + 1
+	// PreparedStatementOriginSQL signifies the prepared statement was made
+	// over a parsed SQL query.
+	PreparedStatementOriginSQL
+)
+
 // PreparedStatement is a SQL statement that has been parsed and the types
 // of arguments and results have been determined.
 //
@@ -44,6 +58,13 @@ type PreparedStatement struct {
 	// statement.
 	refCount int
 	memAcc   mon.BoundAccount
+
+	// createdAt is the timestamp this prepare statement was made at.
+	// Used for reporting on `pg_prepared_statements`.
+	createdAt time.Time
+	// origin is the protocol in which this prepare statement was created.
+	// Used for reporting on `pg_prepared_statements`.
+	origin PreparedStatementOrigin
 }
 
 // MemoryEstimate returns a rough estimate of the PreparedStatement's memory
@@ -79,6 +100,9 @@ func (p *PreparedStatement) incRef(ctx context.Context) {
 // preparedStatementsAccessor gives a planner access to a session's collection
 // of prepared statements.
 type preparedStatementsAccessor interface {
+	// List returns all prepared statements as a map keyed by name.
+	// The map itself is a copy the prepared statements.
+	List() map[string]*PreparedStatement
 	// Get returns the prepared statement with the given name. The returned bool
 	// is false if a statement with the given name doesn't exist.
 	Get(name string) (*PreparedStatement, bool)

pkg/sql/sqlbase/constants.go

@@ -135,6 +135,7 @@ const (
 	PgCatalogMatViewsTableID
 	PgCatalogNamespaceTableID
 	PgCatalogOperatorTableID
+	PgCatalogPreparedStatementsTableID
 	PgCatalogPreparedXactsTableID
 	PgCatalogProcTableID
 	PgCatalogRangeTableID

pkg/sql/sqlbase/prepared_statement.go

@@ -57,5 +57,6 @@ func (pm *PrepareMetadata) MemoryEstimate() int64 {
 
 	res += int64(len(pm.Columns)) * int64(unsafe.Sizeof(ResultColumn{}))
 	res += int64(len(pm.InferredTypes)) * int64(unsafe.Sizeof(oid.Oid(0)))
+
 	return res
 }