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pgwire: fix for specific cases of unnamed portal execution #83164

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83 changes: 70 additions & 13 deletions pkg/sql/pgwire/command_result.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,6 @@ package pgwire

import (
"context"
"fmt"
"time"

"github.com/cockroachdb/cockroach/pkg/col/coldata"
Expand Down Expand Up @@ -462,6 +461,18 @@ func (r *limitedCommandResult) moreResultsNeeded(ctx context.Context) error {
// Keep track of the previous CmdPos so we can rewind if needed.
prevPos := r.conn.stmtBuf.AdvanceOne()
for {
// If the portal is immediately followed by a COMMIT, we can proceed and
// let the portal be destroyed at the end of the transaction.
if isCommit, err := r.isCommit(ctx); err != nil {
return err
} else if isCommit {
return r.rewindAndClosePortal(ctx, prevPos)
}
if shouldClose, err := r.shouldCloseUnnamedPortal(ctx); err != nil {
return err
} else if shouldClose {
return r.rewindAndClosePortal(ctx, prevPos)
}
cmd, curPos, err := r.conn.stmtBuf.CurCmd()
if err != nil {
return err
Expand Down Expand Up @@ -508,27 +519,22 @@ func (r *limitedCommandResult) moreResultsNeeded(ctx context.Context) error {
return err
}
default:
// If the portal is immediately followed by a COMMIT, we can proceed and
// let the portal be destroyed at the end of the transaction.
if isCommit, err := r.isCommit(); err != nil {
return err
} else if isCommit {
return r.rewindAndClosePortal(ctx, prevPos)
}
// We got some other message, but we only support executing to completion.
telemetry.Inc(sqltelemetry.InterleavedPortalRequestCounter)
return errors.WithDetail(sql.ErrLimitedResultNotSupported,
fmt.Sprintf("cannot perform operation %T while a different portal is open", c))
return errors.WithDetailf(sql.ErrLimitedResultNotSupported,
"cannot perform operation %T while a different portal is open", c)
}
prevPos = curPos
}
}

// isCommit checks if the statement buffer has a COMMIT at the current
// position. It may either be (1) a COMMIT in the simple protocol, or (2) a
// Parse/Bind/Execute sequence for a COMMIT query.
func (r *limitedCommandResult) isCommit() (bool, error) {
cmd, _, err := r.conn.stmtBuf.CurCmd()
// Parse/Bind/Execute sequence for a COMMIT query. This peeks ahead in the
// statement buffer, but does not advance the position.
func (r *limitedCommandResult) isCommit(ctx context.Context) (bool, error) {
cmd, curPos, err := r.conn.stmtBuf.CurCmd()
defer r.conn.stmtBuf.Rewind(ctx, curPos)
if err != nil {
return false, err
}
Expand Down Expand Up @@ -584,6 +590,57 @@ func (r *limitedCommandResult) isCommit() (bool, error) {
return false, nil
}

// shouldCloseUnnamedPortal checks if the current portal is the unnamed portal
// and if it should be closed. The Postgres docs specify that:
// "An unnamed portal is destroyed at the end of the transaction, or as soon as
// the next Bind statement specifying the unnamed portal as destination is
// issued. (Note that a simple Query message also destroys the unnamed portal.)"
// This function peeks ahead in the statement buffer, but does not advance the
// position.
func (r *limitedCommandResult) shouldCloseUnnamedPortal(ctx context.Context) (bool, error) {
if r.portalName != "" {
return false, nil
}
cmd, curPos, err := r.conn.stmtBuf.CurCmd()
defer r.conn.stmtBuf.Rewind(ctx, curPos)
if err != nil {
return false, err
}
// Case 1: Check if cmd is a simple query.
if _, ok := cmd.(sql.ExecStmt); ok {
return true, nil
}
// Case 2: Check if cmd is a Bind for an unnamed portal.
if bindStmt, ok := cmd.(sql.BindStmt); ok {
if bindStmt.PortalName == "" {
return true, nil
}
}
// Case 3: Check if cmd is a Prepare followed by a Bind for an unnamed portal.
if prepareStmt, ok := cmd.(sql.PrepareStmt); ok {
r.conn.stmtBuf.AdvanceOne()
cmd, _, err = r.conn.stmtBuf.CurCmd()
if err != nil {
return false, err
}
// Allow Describe, but just skip over it.
if _, ok := cmd.(sql.DescribeStmt); ok {
r.conn.stmtBuf.AdvanceOne()
cmd, _, err = r.conn.stmtBuf.CurCmd()
if err != nil {
return false, err
}
}
// The next cmd must be a bind command for the prepared statement.
if bindStmt, ok := cmd.(sql.BindStmt); ok {
if bindStmt.PreparedStatementName == prepareStmt.Name && bindStmt.PortalName == "" {
return true, nil
}
}
}
return false, nil
}

// rewindAndClosePortal closes the portal in the same way implicit transactions
// do, but also rewinds the stmtBuf to still point to the portal close so that
// the state machine can do its part of the cleanup.
Expand Down
78 changes: 78 additions & 0 deletions pkg/sql/pgwire/testdata/pgtest/portals
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Original file line number Diff line number Diff line change
Expand Up @@ -1394,3 +1394,81 @@ ReadyForQuery
{"Type":"DataRow","Values":[{"text":"2"}]}
{"Type":"CommandComplete","CommandTag":"FETCH 2"}
{"Type":"ReadyForQuery","TxStatus":"T"}

# Test for executing/re-preparing unnamed portal. PG docs say:
# "An unnamed portal is destroyed at the end of the transaction, or as soon as
# the next Bind statement specifying the unnamed portal as destination is
# issued. (Note that a simple Query message also destroys the unnamed portal.)"

send
Parse {"Query": "SELECT * FROM generate_series(1, 4)"}
Bind
Execute {"MaxRows": 1}
Parse {"Name": "s17", "Query": "SELECT * FROM generate_series(10, 14)"}
Bind {"PreparedStatement": "s17"}
Execute {"MaxRows": 1}
Sync
----

until
ReadyForQuery
----
{"Type":"ParseComplete"}
{"Type":"BindComplete"}
{"Type":"DataRow","Values":[{"text":"1"}]}
{"Type":"PortalSuspended"}
{"Type":"ParseComplete"}
{"Type":"BindComplete"}
{"Type":"DataRow","Values":[{"text":"10"}]}
{"Type":"PortalSuspended"}
{"Type":"ReadyForQuery","TxStatus":"I"}

# A Describe between Parse and Bind is also allowed.

send
Parse {"Query": "SELECT * FROM generate_series(1, 4)"}
Bind
Execute {"MaxRows": 1}
Parse {"Query": "SELECT n::INT4 FROM generate_series(10, 14) n"}
Describe {"ObjectType": "S"}
Bind
Execute {"MaxRows": 1}
Sync
----

until
ReadyForQuery
----
{"Type":"ParseComplete"}
{"Type":"BindComplete"}
{"Type":"DataRow","Values":[{"text":"1"}]}
{"Type":"PortalSuspended"}
{"Type":"ParseComplete"}
{"Type":"ParameterDescription","ParameterOIDs":null}
{"Type":"RowDescription","Fields":[{"Name":"n","TableOID":0,"TableAttributeNumber":0,"DataTypeOID":23,"DataTypeSize":4,"TypeModifier":-1,"Format":0}]}
{"Type":"BindComplete"}
{"Type":"DataRow","Values":[{"text":"10"}]}
{"Type":"PortalSuspended"}
{"Type":"ReadyForQuery","TxStatus":"I"}

send
Parse {"Query": "SELECT * FROM generate_series(1, 4)"}
Bind
Execute {"MaxRows": 1}
Query {"String": "SELECT n::INT4 FROM generate_series(10, 12) n"}
Sync
----

until
ReadyForQuery
----
{"Type":"ParseComplete"}
{"Type":"BindComplete"}
{"Type":"DataRow","Values":[{"text":"1"}]}
{"Type":"PortalSuspended"}
{"Type":"RowDescription","Fields":[{"Name":"n","TableOID":0,"TableAttributeNumber":0,"DataTypeOID":23,"DataTypeSize":4,"TypeModifier":-1,"Format":0}]}
{"Type":"DataRow","Values":[{"text":"10"}]}
{"Type":"DataRow","Values":[{"text":"11"}]}
{"Type":"DataRow","Values":[{"text":"12"}]}
{"Type":"CommandComplete","CommandTag":"SELECT 3"}
{"Type":"ReadyForQuery","TxStatus":"I"}