feat: restore data in batches

* Introduced the --batch-size flag for the restore command.
* The COPY command will complete after reaching the specified batch size, allowing for transaction state checks.
* The transaction spans across all batches.
* If an error occurs in any batch, all previous batches will be rolled back.

cmd/greenmask/cmd/restore/restore.go

@@ -171,6 +171,10 @@ func init() {
 		"pgzip", "", false,
 		"use pgzip decompression instead of gzip",
 	)
+	Cmd.Flags().Int64P(
+		"batch-size", "", 0,
+		"the number of rows to insert in a single batch during the COPY command (0 - all rows will be inserted in a single batch)",
+	)
 
 	// Connection options:
 	Cmd.Flags().StringP("host", "h", "/var/run/postgres", "database server host or socket directory")
@@ -185,7 +189,7 @@ func init() {
 		"disable-triggers", "enable-row-security", "if-exists", "no-comments", "no-data-for-failed-tables",
 		"no-security-labels", "no-subscriptions", "no-table-access-method", "no-tablespaces", "section",
 		"strict-names", "use-set-session-authorization", "inserts", "on-conflict-do-nothing", "restore-in-order",
-		"pgzip",
+		"pgzip", "batch-size",
 
 		"host", "port", "username",
 	} {

docs/commands/restore.md

@@ -18,6 +18,7 @@ allowing you to configure the restoration process as needed.
 Mostly it supports the same flags as the `pg_restore` utility, with some extra flags for Greenmask-specific features.
 
 ```text title="Supported flags"
+      --batch-size int                  the number of rows to insert in a single batch during the COPY command (0 - all rows will be inserted in a single batch)
   -c, --clean                           clean (drop) database objects before recreating
   -C, --create                          create the target database
   -a, --data-only                       restore only the data, no schema
@@ -112,5 +113,28 @@ If your database has cyclic dependencies you will be notified about it but the r
 By default, Greenmask uses gzip decompression to restore data. In mist cases it is quite slow and does not utilize all
 available resources and is a bootleneck for IO operations. To speed up the restoration process, you can use
 the `--pgzip` flag to use pgzip decompression instead of gzip. This method splits the data into blocks, which are
-decompressed in parallel, making it ideal for handling large volumes of data. The output remains a standard gzip file.
+decompressed in parallel, making it ideal for handling large volumes of data.
 
+```shell title="example with pgzip decompression"
+greenmask --config=config.yml restore latest --pgzip
+```
+
+### Restore data batching
+
+The COPY command returns the error only on transaction commit. This means that if you have a large dump and an error
+occurs, you will have to wait until the end of the transaction to see the error message. To avoid this, you can use the
+`--batch-size` flag to specify the number of rows to insert in a single batch during the COPY command. If an error occurs
+during the batch insertion, the error message will be displayed immediately. The data will be committed **only if all 
+batches are inserted successfully**.
+
+!!! warning
+
+    The batch size should be chosen carefully. If the batch size is too small, the restoration process will be slow. If
+    the batch size is too large, you may not be able to identify the error row.
+
+In the example below, the batch size is set to 1000 rows. This means that 1000 rows will be inserted in a single batch,
+so you will be notified of any errors immediately after each batch is inserted.
+
+```shell title="example with batch size" 
+greenmask --config=config.yml restore latest --batch-size 1000
+```

internal/db/postgres/cmd/restore.go

@@ -646,7 +646,9 @@ func (r *Restore) taskPusher(ctx context.Context, tasks chan restorers.RestoreTa
 							r.cfg.ErrorExclusions, r.restoreOpt.Pgzip,
 						)
 					} else {
-						task = restorers.NewTableRestorer(entry, r.st, r.restoreOpt.ExitOnError, r.restoreOpt.Pgzip)
+						task = restorers.NewTableRestorer(
+							entry, r.st, r.restoreOpt.ExitOnError, r.restoreOpt.Pgzip, r.restoreOpt.BatchSize,
+						)
 					}
 
 				case toc.SequenceSetDesc:

internal/db/postgres/cmd/validate.go

@@ -223,7 +223,7 @@ func (v *Validate) readRecords(r *bufio.Reader, t *entries.Table) (original, tra
 	originalRow = pgcopy.NewRow(len(t.Columns))
 	transformedRow = pgcopy.NewRow(len(t.Columns))
 
-	originalLine, err = reader.ReadLine(r)
+	originalLine, err = reader.ReadLine(r, nil)
 	if err != nil {
 		if errors.Is(err, io.EOF) {
 			return nil, nil, err
@@ -235,7 +235,7 @@ func (v *Validate) readRecords(r *bufio.Reader, t *entries.Table) (original, tra
 		return nil, nil, io.EOF
 	}
 
-	transformedLine, err = reader.ReadLine(r)
+	transformedLine, err = reader.ReadLine(r, nil)
 	if err != nil {
 		return nil, nil, fmt.Errorf("unable to read line: %w", err)
 	}

internal/db/postgres/pgrestore/pgrestore.go

@@ -97,7 +97,8 @@ type Options struct {
 	Inserts             bool `mapstructure:"inserts"`
 	RestoreInOrder      bool `mapstructure:"restore-in-order"`
 	// Use pgzip decompression instead of gzip
-	Pgzip bool `mapstructure:"pgzip"`
+	Pgzip     bool  `mapstructure:"pgzip"`
+	BatchSize int64 `mapstructure:"batch-size"`
 
 	// Connection options:
 	Host       string `mapstructure:"host"`

internal/db/postgres/restorers/table.go

@@ -15,13 +15,15 @@
 package restorers
 
 import (
+	"bufio"
 	"context"
 	"errors"
 	"fmt"
 	"io"
 
 	"github.com/greenmaskio/greenmask/internal/utils/ioutils"
 	"github.com/greenmaskio/greenmask/internal/utils/pgerrors"
+	"github.com/greenmaskio/greenmask/internal/utils/reader"
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgproto3"
 	"github.com/rs/zerolog/log"
@@ -37,14 +39,18 @@ type TableRestorer struct {
 	St          storages.Storager
 	exitOnError bool
 	usePgzip    bool
+	batchSize   int64
 }
 
-func NewTableRestorer(entry *toc.Entry, st storages.Storager, exitOnError bool, usePgzip bool) *TableRestorer {
+func NewTableRestorer(
+	entry *toc.Entry, st storages.Storager, exitOnError bool, usePgzip bool, batchSize int64,
+) *TableRestorer {
 	return &TableRestorer{
 		Entry:       entry,
 		St:          st,
 		exitOnError: exitOnError,
 		usePgzip:    usePgzip,
+		batchSize:   batchSize,
 	}
 }
 
@@ -117,8 +123,14 @@ func (td *TableRestorer) restoreCopy(ctx context.Context, f *pgproto3.Frontend,
 		return fmt.Errorf("error initializing pgcopy: %w", err)
 	}
 
-	if err := td.streamCopyData(ctx, f, r); err != nil {
-		return fmt.Errorf("error streaming pgcopy data: %w", err)
+	if td.batchSize > 0 {
+		if err := td.streamCopyDataByBatch(ctx, f, r); err != nil {
+			return fmt.Errorf("error streaming pgcopy data: %w", err)
+		}
+	} else {
+		if err := td.streamCopyData(ctx, f, r); err != nil {
+			return fmt.Errorf("error streaming pgcopy data: %w", err)
+		}
 	}
 
 	if err := td.postStreamingHandle(ctx, f); err != nil {
@@ -134,8 +146,7 @@ func (td *TableRestorer) initCopy(ctx context.Context, f *pgproto3.Frontend) err
 	}
 
 	// Prepare for streaming the pgcopy data
-	process := true
-	for process {
+	for {
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
@@ -148,35 +159,67 @@ func (td *TableRestorer) initCopy(ctx context.Context, f *pgproto3.Frontend) err
 		}
 		switch v := msg.(type) {
 		case *pgproto3.CopyInResponse:
-			process = false
+			return nil
 		case *pgproto3.ErrorResponse:
 			return fmt.Errorf("error from postgres connection: %w", pgerrors.NewPgError(v))
 		default:
 			return fmt.Errorf("unknown message %+v", v)
 		}
 	}
-	return nil
 }
 
-func (td *TableRestorer) streamCopyData(ctx context.Context, f *pgproto3.Frontend, r io.Reader) error {
-	// Streaming pgcopy data from table dump
-
+// streamCopyDataByBatch - stream pgcopy data from table dump in batches. It handles errors only on the end each batch
+// If the batch size is reached it completes the batch and starts a new one. If an error occurs during the batch it
+// stops immediately and returns the error
+func (td *TableRestorer) streamCopyDataByBatch(ctx context.Context, f *pgproto3.Frontend, r io.Reader) (err error) {
+	bi := bufio.NewReader(r)
 	buf := make([]byte, DefaultBufferSize)
+	var lineNum int64
 	for {
-		var n int
+		buf, err = reader.ReadLine(bi, buf)
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			return fmt.Errorf("error readimg from table dump: %w", err)
+		}
+		if isTerminationSeq(buf) {
+			break
+		}
+		lineNum++
+		buf = append(buf, '\n')
+
+		err = sendMessage(f, &pgproto3.CopyData{Data: buf})
+		if err != nil {
+			return fmt.Errorf("error sending CopyData message: %w", err)
+		}
+
+		if lineNum%td.batchSize == 0 {
+			if err = td.completeBatch(ctx, f); err != nil {
+				return fmt.Errorf("error completing batch: %w", err)
+			}
+		}
+
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
 		default:
 		}
+	}
+	return nil
+}
+
+// streamCopyData - stream pgcopy data from table dump in classic way. It handles errors only on the end of the stream
+func (td *TableRestorer) streamCopyData(ctx context.Context, f *pgproto3.Frontend, r io.Reader) error {
+	// Streaming pgcopy data from table dump
+
+	buf := make([]byte, DefaultBufferSize)
+	for {
+		var n int
 
 		n, err := r.Read(buf)
 		if err != nil {
 			if errors.Is(err, io.EOF) {
-				completionErr := sendMessage(f, &pgproto3.CopyDone{})
-				if completionErr != nil {
-					return fmt.Errorf("error sending CopyDone message: %w", err)
-				}
 				break
 			}
 			return fmt.Errorf("error readimg from table dump: %w", err)
@@ -186,12 +229,32 @@ func (td *TableRestorer) streamCopyData(ctx context.Context, f *pgproto3.Fronten
 		if err != nil {
 			return fmt.Errorf("error sending DopyData message: %w", err)
 		}
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+	}
+	return nil
+}
+
+// completeBatch - complete batch of pgcopy data and initiate new one
+func (td *TableRestorer) completeBatch(ctx context.Context, f *pgproto3.Frontend) error {
+	if err := td.postStreamingHandle(ctx, f); err != nil {
+		return err
+	}
+	if err := td.initCopy(ctx, f); err != nil {
+		return err
 	}
 	return nil
 }
 
 func (td *TableRestorer) postStreamingHandle(ctx context.Context, f *pgproto3.Frontend) error {
 	// Perform post streaming handling
+	err := sendMessage(f, &pgproto3.CopyDone{})
+	if err != nil {
+		return fmt.Errorf("error sending CopyDone message: %w", err)
+	}
 	var mainErr error
 	for {
 		select {

internal/db/postgres/restorers/table_insert_format.go

@@ -140,7 +140,7 @@ func (td *TableRestorerInsertFormat) streamInsertData(ctx context.Context, conn
 		default:
 		}
 
-		line, err := reader.ReadLine(buf)
+		line, err := reader.ReadLine(buf, nil)
 		if err != nil {
 			if errors.Is(err, io.EOF) {
 				break

internal/db/postgres/transformers/custom/dynamic_definition.go

@@ -85,7 +85,7 @@ func GetDynamicTransformerDefinition(ctx context.Context, executable string, arg
 
 				buf := bufio.NewReader(bytes.NewBuffer(stdoutData))
 				for {
-					line, err := reader.ReadLine(buf)
+					line, err := reader.ReadLine(buf, nil)
 					if err != nil {
 						break
 					}
@@ -102,7 +102,7 @@ func GetDynamicTransformerDefinition(ctx context.Context, executable string, arg
 
 				buf := bufio.NewReader(bytes.NewBuffer(stderrData))
 				for {
-					line, err := reader.ReadLine(buf)
+					line, err := reader.ReadLine(buf, nil)
 					if err != nil {
 						break
 					}

internal/db/postgres/transformers/utils/cmd_transformer_base.go

@@ -315,7 +315,7 @@ func (ctb *CmdTransformerBase) init() error {
 
 func (ctb *CmdTransformerBase) ReceiveStderrLine(ctx context.Context) (line []byte, err error) {
 	go func() {
-		line, err = reader.ReadLine(ctb.StderrReader)
+		line, err = reader.ReadLine(ctb.StderrReader, nil)
 		ctb.receiveChan <- struct{}{}
 	}()
 	select {
@@ -333,7 +333,7 @@ func (ctb *CmdTransformerBase) ReceiveStderrLine(ctx context.Context) (line []by
 
 func (ctb *CmdTransformerBase) ReceiveStdoutLine(ctx context.Context) (line []byte, err error) {
 	go func() {
-		line, err = reader.ReadLine(ctb.StdoutReader)
+		line, err = reader.ReadLine(ctb.StdoutReader, nil)
 		ctb.receiveChan <- struct{}{}
 	}()
 	select {

internal/utils/cmd_runner/cmd_runner.go

@@ -53,7 +53,7 @@ func Run(ctx context.Context, logger *zerolog.Logger, name string, args ...strin
 				return gtx.Err()
 			default:
 			}
-			line, err := reader.ReadLine(lineScanner)
+			line, err := reader.ReadLine(lineScanner, nil)
 			if err != nil {
 				if errors.Is(err, io.EOF) {
 					return nil
@@ -73,7 +73,7 @@ func Run(ctx context.Context, logger *zerolog.Logger, name string, args ...strin
 				return gtx.Err()
 			default:
 			}
-			line, err := reader.ReadLine(lineScanner)
+			line, err := reader.ReadLine(lineScanner, nil)
 			if err != nil {
 				if errors.Is(err, io.EOF) {
 					return nil

internal/utils/reader/reader.go

@@ -5,18 +5,18 @@ import (
 	"fmt"
 )
 
-func ReadLine(r *bufio.Reader) ([]byte, error) {
-	var res []byte
+func ReadLine(r *bufio.Reader, buf []byte) ([]byte, error) {
+	buf = buf[:0]
 	for {
 		var line []byte
 		line, isPrefix, err := r.ReadLine()
 		if err != nil {
 			return nil, fmt.Errorf("unable to read line: %w", err)
 		}
-		res = append(res, line...)
+		buf = append(buf, line...)
 		if !isPrefix {
 			break
 		}
 	}
-	return res, nil
+	return buf, nil
 }