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Fix PostgreSQL backfill chunking for UUID and string types #522

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Fix PostgreSQL backfill chunking for UUID and string types #522

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7 changes: 4 additions & 3 deletions drivers/postgres/internal/backfill.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,8 @@ func (p *Postgres) ChunkIterator(ctx context.Context, stream types.StreamInterfa
defer tx.Rollback()
chunkColumn := stream.Self().StreamMetadata.ChunkColumn
chunkColumn = utils.Ternary(chunkColumn == "", "ctid", chunkColumn).(string)
stmt := jdbc.PostgresChunkScanQuery(stream, chunkColumn, chunk, filter)
chunkColType, _ := stream.Schema().GetType(chunkColumn)
stmt := jdbc.PostgresChunkScanQuery(stream, chunkColumn, chunk, filter, chunkColType)
setter := jdbc.NewReader(ctx, stmt, p.config.BatchSize, func(ctx context.Context, query string, args ...any) (*sql.Rows, error) {
return tx.Query(query, args...)
})
Expand Down Expand Up @@ -129,7 +130,6 @@ func (p *Postgres) splitTableIntoChunks(stream types.StreamInterface) (*types.Se
if chunkColumn != "" {
var minValue, maxValue interface{}
minMaxRowCountQuery := jdbc.MinMaxQuery(stream, chunkColumn)
// TODO: Fails on UUID type (Good First Issue)
err := p.client.QueryRow(minMaxRowCountQuery).Scan(&minValue, &maxValue)
if err != nil {
return nil, fmt.Errorf("failed to fetch table min max: %s", err)
Expand Down Expand Up @@ -158,7 +158,8 @@ func (p *Postgres) splitTableIntoChunks(stream types.StreamInterface) (*types.Se

func (p *Postgres) nextChunkEnd(stream types.StreamInterface, previousChunkEnd interface{}, chunkColumn string) (interface{}, error) {
var chunkEnd interface{}
nextChunkEnd := jdbc.PostgresNextChunkEndQuery(stream, chunkColumn, previousChunkEnd, p.config.BatchSize)
chunkColType, _ := stream.Schema().GetType(chunkColumn)
nextChunkEnd := jdbc.PostgresNextChunkEndQuery(stream, chunkColumn, previousChunkEnd, p.config.BatchSize, chunkColType)
err := p.client.QueryRow(nextChunkEnd).Scan(&chunkEnd)
if err != nil {
return nil, fmt.Errorf("failed to query[%s] next chunk end: %s", nextChunkEnd, err)
Expand Down
24 changes: 18 additions & 6 deletions pkg/jdbc/jdbc.go
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Expand Up @@ -127,26 +127,38 @@ func PostgresWalLSNQuery() string {
}

// PostgresNextChunkEndQuery generates a SQL query to fetch the maximum value of a specified column
func PostgresNextChunkEndQuery(stream types.StreamInterface, filterColumn string, filterValue interface{}, batchSize int) string {
func PostgresNextChunkEndQuery(stream types.StreamInterface, filterColumn string, filterValue interface{}, batchSize int, dataType types.DataType) string {
quotedColumn := QuoteIdentifier(filterColumn, constants.Postgres)
quotedTable := QuoteTable(stream.Namespace(), stream.Name(), constants.Postgres)
baseCond := fmt.Sprintf(`%s > %v`, quotedColumn, filterValue)
var baseCond string
if dataType == types.String {
baseCond = fmt.Sprintf(`%s > '%s'`, quotedColumn, strings.ReplaceAll(fmt.Sprintf("%v", filterValue), "'", "''"))
} else {
baseCond = fmt.Sprintf(`%s > %v`, quotedColumn, filterValue)
}
return fmt.Sprintf(`SELECT MAX(%s) FROM (SELECT %s FROM %s WHERE %s ORDER BY %s ASC LIMIT %d) AS T`,
quotedColumn, quotedColumn, quotedTable, baseCond, quotedColumn, batchSize)
}

// PostgresBuildSplitScanQuery builds a chunk scan query for PostgreSQL
func PostgresChunkScanQuery(stream types.StreamInterface, filterColumn string, chunk types.Chunk, filter string) string {
func PostgresChunkScanQuery(stream types.StreamInterface, filterColumn string, chunk types.Chunk, filter string, dataType types.DataType) string {
quotedFilterColumn := QuoteIdentifier(filterColumn, constants.Postgres)
quotedTable := QuoteTable(stream.Namespace(), stream.Name(), constants.Postgres)

formatValue := func(val interface{}) string {
if dataType == types.String && val != nil {
return fmt.Sprintf("'%s'", strings.ReplaceAll(fmt.Sprintf("%v", val), "'", "''"))
}
return fmt.Sprintf("%v", val)
}

chunkCond := ""
if chunk.Min != nil && chunk.Max != nil {
chunkCond = fmt.Sprintf("%s >= %v AND %s < %v", quotedFilterColumn, chunk.Min, quotedFilterColumn, chunk.Max)
chunkCond = fmt.Sprintf("%s >= %s AND %s < %s", quotedFilterColumn, formatValue(chunk.Min), quotedFilterColumn, formatValue(chunk.Max))
} else if chunk.Min != nil {
chunkCond = fmt.Sprintf("%s >= %v", quotedFilterColumn, chunk.Min)
chunkCond = fmt.Sprintf("%s >= %s", quotedFilterColumn, formatValue(chunk.Min))
} else if chunk.Max != nil {
chunkCond = fmt.Sprintf("%s < %v", quotedFilterColumn, chunk.Max)
chunkCond = fmt.Sprintf("%s < %s", quotedFilterColumn, formatValue(chunk.Max))
}

chunkCond = utils.Ternary(filter != "" && chunkCond != "", fmt.Sprintf("(%s) AND (%s)", chunkCond, filter), chunkCond).(string)
Expand Down