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stmt.go
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stmt.go
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package driver
import (
"context"
"database/sql"
"database/sql/driver"
"errors"
"fmt"
"slices"
"time"
p "github.com/SAP/go-hdb/driver/internal/protocol"
)
// check if statements implements all required interfaces.
var (
_ driver.Stmt = (*stmt)(nil)
_ driver.StmtExecContext = (*stmt)(nil)
_ driver.StmtQueryContext = (*stmt)(nil)
_ driver.NamedValueChecker = (*stmt)(nil)
)
type stmt struct {
conn *conn
query string
pr *prepareResult
// rows: stored procedures with table output parameters
rows *sql.Rows
}
type totalRowsAffected int64
func (t *totalRowsAffected) add(r driver.Result) {
if r == nil {
return
}
rows, err := r.RowsAffected()
if err != nil {
return
}
*t += totalRowsAffected(rows)
}
func newStmt(conn *conn, query string, pr *prepareResult) *stmt {
conn.metrics.msgCh <- gaugeMsg{idx: gaugeStmt, v: 1} // increment number of statements.
return &stmt{conn: conn, query: query, pr: pr}
}
/*
NumInput differs dependent on statement (check is done in QueryContext and ExecContext):
- #args == #param (only in params): query, exec, exec bulk (non control query)
- #args == #param (in and out params): exec call
- #args == 0: exec bulk (control query)
- #args == #input param: query call.
*/
func (s *stmt) NumInput() int { return -1 }
func (s *stmt) Close() error {
c := s.conn
c.metrics.msgCh <- gaugeMsg{idx: gaugeStmt, v: -1} // decrement number of statements.
if s.rows != nil {
s.rows.Close()
}
if c.isBad() {
return driver.ErrBadConn
}
return c.dropStatementID(context.Background(), s.pr.stmtID)
}
// CheckNamedValue implements NamedValueChecker interface.
func (s *stmt) CheckNamedValue(nv *driver.NamedValue) error {
// conversion is happening as part of the exec, query call
return nil
}
func (s *stmt) QueryContext(ctx context.Context, nvargs []driver.NamedValue) (driver.Rows, error) {
if s.pr.isProcedureCall() {
return nil, fmt.Errorf("invalid procedure call %s - please use Exec instead", s.query)
}
c := s.conn
if c.sqlTrace {
defer c.logSQLTrace(ctx, time.Now(), s.query, nvargs)
}
done := make(chan struct{})
var rows driver.Rows
var err error
c.wg.Add(1)
go func() {
defer c.wg.Done()
rows, err = c.query(ctx, s.pr, nvargs, !s.conn.inTx)
close(done)
}()
select {
case <-ctx.Done():
c.lastError = errCancelled
return nil, ctx.Err()
case <-done:
c.lastError = err
return rows, err
}
}
func (s *stmt) ExecContext(ctx context.Context, nvargs []driver.NamedValue) (driver.Result, error) {
c := s.conn
if connHook != nil {
connHook(c, choStmtExec)
}
if c.sqlTrace {
defer c.logSQLTrace(ctx, time.Now(), s.query, nvargs)
}
done := make(chan struct{})
var result driver.Result
var err error
c.wg.Add(1)
go func() {
defer c.wg.Done()
if s.pr.isProcedureCall() {
result, s.rows, err = s.execCall(ctx, s.pr, nvargs)
} else {
result, err = s.execDefault(ctx, nvargs)
}
close(done)
}()
select {
case <-ctx.Done():
c.lastError = errCancelled
return nil, ctx.Err()
case <-done:
c.lastError = err
return result, err
}
}
func (s *stmt) execCall(ctx context.Context, pr *prepareResult, nvargs []driver.NamedValue) (driver.Result, *sql.Rows, error) {
c := s.conn
defer c.addSQLTimeValue(time.Now(), sqlTimeCall)
callArgs, err := convertCallArgs(pr.parameterFields, nvargs, c.attrs._cesu8Encoder(), c.attrs._lobChunkSize)
if err != nil {
return nil, nil, err
}
inputParameters, err := p.NewInputParameters(callArgs.inFields, callArgs.inArgs)
if err != nil {
return nil, nil, err
}
if err := c.pw.Write(ctx, c.sessionID, p.MtExecute, false, (*p.StatementID)(&pr.stmtID), inputParameters); err != nil {
return nil, nil, err
}
/*
call without lob input parameters:
--> callResult output parameter values are set after read call
call with lob output parameters:
--> callResult output parameter values are set after last lob input write
*/
cr, ids, numRow, err := c.execCall(ctx, callArgs.outFields)
if err != nil {
return nil, nil, err
}
if len(ids) != 0 {
/*
writeLobParameters:
- chunkReaders
- cr (callResult output parameters are set after all lob input parameters are written)
*/
if err := c.writeLobs(ctx, cr, ids, callArgs.inFields, callArgs.inArgs); err != nil {
return nil, nil, err
}
}
numOutputField := len(cr.outputFields)
// no output fields -> done
if numOutputField == 0 {
return driver.RowsAffected(numRow), nil, nil
}
scanArgs := make([]any, numOutputField)
for i := 0; i < numOutputField; i++ {
scanArgs[i] = callArgs.outArgs[i].Value.(sql.Out).Dest
}
// no table output parameters -> QueryRow
if len(callArgs.outFields) == len(callArgs.outArgs) {
if err := stdConnTracker.callDB().QueryRow("", cr).Scan(scanArgs...); err != nil {
return nil, nil, err
}
return driver.RowsAffected(numRow), nil, nil
}
// table output parameters -> Query (needs to kept open)
rows, err := stdConnTracker.callDB().Query("", cr)
if err != nil {
return nil, rows, err
}
if !rows.Next() {
return nil, rows, rows.Err()
}
if err := rows.Scan(scanArgs...); err != nil {
return nil, rows, err
}
return driver.RowsAffected(numRow), rows, nil
}
func (s *stmt) execDefault(ctx context.Context, nvargs []driver.NamedValue) (driver.Result, error) {
c := s.conn
numNVArg, numField := len(nvargs), s.pr.numField()
if numNVArg == 0 {
if numField != 0 {
return nil, fmt.Errorf("invalid number of arguments %d - expected %d", numNVArg, numField)
}
return c.exec(ctx, s.pr, nvargs, !c.inTx, 0)
}
if numNVArg == 1 {
if _, ok := nvargs[0].Value.(func(args []any) error); ok {
return s.execFct(ctx, nvargs)
}
}
if numNVArg == numField {
return s.exec(ctx, s.pr, nvargs, !c.inTx, 0)
}
if numNVArg%numField != 0 {
return nil, fmt.Errorf("invalid number of arguments %d - multiple of %d expected", numNVArg, numField)
}
return s.execMany(ctx, nvargs)
}
// ErrEndOfRows is the error to be returned using a function based bulk exec to indicate
// the end of rows.
var ErrEndOfRows = errors.New("end of rows")
/*
Non 'atomic' (transactional) operation due to the split in packages (bulkSize),
execMany data might only be written partially to the database in case of hdb stmt errors.
*/
func (s *stmt) execFct(ctx context.Context, nvargs []driver.NamedValue) (driver.Result, error) {
c := s.conn
totalRowsAffected := totalRowsAffected(0)
args := make([]driver.NamedValue, 0, s.pr.numField())
scanArgs := make([]any, s.pr.numField())
fct, ok := nvargs[0].Value.(func(args []any) error)
if !ok {
panic("should never happen")
}
done := false
batch := 0
for !done {
args = args[:0]
for i := 0; i < c.attrs._bulkSize; i++ {
err := fct(scanArgs)
if errors.Is(err, ErrEndOfRows) {
done = true
break
}
if err != nil {
return driver.RowsAffected(totalRowsAffected), err
}
args = slices.Grow(args, len(scanArgs))
for j, scanArg := range scanArgs {
nv := driver.NamedValue{Ordinal: j + 1}
if t, ok := scanArg.(sql.NamedArg); ok {
nv.Name = t.Name
nv.Value = t.Value
} else {
nv.Name = ""
nv.Value = scanArg
}
args = append(args, nv)
}
}
if len(args) != 0 {
r, err := s.exec(ctx, s.pr, args, !c.inTx, batch*c.attrs._bulkSize)
totalRowsAffected.add(r)
if err != nil {
return driver.RowsAffected(totalRowsAffected), err
}
}
batch++
}
return driver.RowsAffected(totalRowsAffected), nil
}
/*
Non 'atomic' (transactional) operation due to the split in packages (bulkSize),
execMany data might only be written partially to the database in case of hdb stmt errors.
*/
func (s *stmt) execMany(ctx context.Context, nvargs []driver.NamedValue) (driver.Result, error) {
c := s.conn
bulkSize := c.attrs._bulkSize
totalRowsAffected := totalRowsAffected(0)
numField := s.pr.numField()
numNVArg := len(nvargs)
numRec := numNVArg / numField
numBatch := numRec / c.attrs._bulkSize
if numRec%c.attrs._bulkSize != 0 {
numBatch++
}
for i := 0; i < numBatch; i++ {
from := i * numField * bulkSize
to := (i + 1) * numField * bulkSize
if to > numNVArg {
to = numNVArg
}
r, err := s.exec(ctx, s.pr, nvargs[from:to], !c.inTx, i*bulkSize)
totalRowsAffected.add(r)
if err != nil {
return driver.RowsAffected(totalRowsAffected), err
}
}
return driver.RowsAffected(totalRowsAffected), nil
}
/*
exec executes a sql statement.
Bulk insert containing LOBs:
- Precondition:
.Sending more than one row with partial LOB data.
- Observations:
.In hdb version 1 and 2 'piecewise' LOB writing does work.
.Same does not work in case of geo fields which are LOBs en,- decoded as well.
.In hana version 4 'piecewise' LOB writing seems not to work anymore at all.
- Server implementation (not documented):
.'piecewise' LOB writing is only supported for the last row of a 'bulk insert'.
- Current implementation:
One server call in case of
.'non bulk' execs or
.'bulk' execs without LOBs
else potential several server calls (split into packages).
- Package invariant:
.for all packages except the last one, the last row contains 'incomplete' LOB data ('piecewise' writing)
*/
func (s *stmt) exec(ctx context.Context, pr *prepareResult, nvargs []driver.NamedValue, commit bool, ofs int) (driver.Result, error) {
c := s.conn
defer c.addSQLTimeValue(time.Now(), sqlTimeExec)
addLobDataRecs, err := convertExecArgs(pr.parameterFields, nvargs, c.attrs._cesu8Encoder(), c.attrs._lobChunkSize)
if err != nil {
return driver.ResultNoRows, err
}
// piecewise LOB handling
numColumn := len(pr.parameterFields)
totalRowsAffected := totalRowsAffected(0)
from := 0
for i := 0; i < len(addLobDataRecs); i++ {
to := (addLobDataRecs[i] + 1) * numColumn
r, err := c.exec(ctx, pr, nvargs[from:to], commit, ofs)
totalRowsAffected.add(r)
if err != nil {
return driver.RowsAffected(totalRowsAffected), err
}
from = to
}
return driver.RowsAffected(totalRowsAffected), nil
}