Fix dates in Parquet, handle bpchar and convert decimal PG types

src/pg_schema_column.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 	"time"
@@ -102,6 +103,11 @@ func (pgSchemaColumn *PgSchemaColumn) FormatParquetValue(value string) *string {
 			timestamp := strconv.FormatInt(parsedTime.UnixMilli(), 10)
 			return &timestamp
 		}
+	case "date":
+		parsedTime, err := time.Parse("2006-01-02", value)
+		PanicIfError(err)
+		date := fmt.Sprintf("%d", parsedTime.Unix()/86400)
+		return &date
 	default:
 		if strings.HasPrefix(pgSchemaColumn.UdtName, "_") {
 			switch strings.TrimLeft(pgSchemaColumn.UdtName, "_") {
@@ -141,7 +147,7 @@ func (pgSchemaColumn PgSchemaColumn) toIcebergSchemaField() IcebergSchemaField {
 	}
 
 	switch pgSchemaColumn.UdtName {
-	case "varchar", "char", "text", "jsonb", "json", "uuid":
+	case "varchar", "char", "text", "jsonb", "json", "uuid", "bpchar":
 		icebergSchemaField.Type = "string"
 	case "int2", "int4", "int8":
 		icebergSchemaField.Type = "int"
@@ -187,7 +193,7 @@ func (pgSchemaColumn *PgSchemaColumn) toParquetSchemaField() ParquetSchemaField
 	}
 
 	switch pgSchemaColumn.UdtName {
-	case "varchar", "char", "text", "bytea", "jsonb", "json":
+	case "varchar", "char", "text", "bytea", "jsonb", "json", "bpchar":
 		parquetSchemaField.Type = "BYTE_ARRAY"
 		parquetSchemaField.ConvertedType = "UTF8"
 	case "int2", "int4", "int8":
@@ -196,10 +202,14 @@ func (pgSchemaColumn *PgSchemaColumn) toParquetSchemaField() ParquetSchemaField
 		parquetSchemaField.Type = "FLOAT"
 	case "numeric":
 		parquetSchemaField.Type = "FIXED_LEN_BYTE_ARRAY"
-		parquetSchemaField.Length = pgSchemaColumn.NumericPrecision + "." + pgSchemaColumn.NumericScale
 		parquetSchemaField.ConvertedType = "DECIMAL"
 		parquetSchemaField.Scale = pgSchemaColumn.NumericScale
 		parquetSchemaField.Precision = pgSchemaColumn.NumericPrecision
+		scale, err := strconv.Atoi(pgSchemaColumn.NumericScale)
+		PanicIfError(err)
+		precision, err := strconv.Atoi(pgSchemaColumn.NumericPrecision)
+		PanicIfError(err)
+		parquetSchemaField.Length = strconv.Itoa(scale + precision)
 	case "bool":
 		parquetSchemaField.Type = "BOOLEAN"
 	case "uuid":

src/proxy.go

@@ -4,9 +4,13 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"fmt"
+	"strconv"
+	"time"
 
 	"github.com/jackc/pgx/v5/pgproto3"
 	"github.com/jackc/pgx/v5/pgtype"
+	duckDB "github.com/marcboeker/go-duckdb"
 	pgQuery "github.com/pganalyze/pg_query_go/v5"
 )
 
@@ -106,23 +110,58 @@ func (proxy *Proxy) generateRowDescription(cols []*sql.ColumnType) *pgproto3.Row
 }
 
 func (proxy *Proxy) generateDataRow(rows *sql.Rows, cols []*sql.ColumnType) (*pgproto3.DataRow, error) {
-	values := make([][]byte, len(cols))
 	valuePtrs := make([]interface{}, len(cols))
-
-	for i := range values {
-		valuePtrs[i] = &values[i]
+	for i, col := range cols {
+		switch col.ScanType().Name() {
+		case "int32":
+			var value int32
+			valuePtrs[i] = &value
+		case "int64":
+			var value int64
+			valuePtrs[i] = &value
+		case "string":
+			var value string
+			valuePtrs[i] = &value
+		case "Time":
+			var value time.Time
+			valuePtrs[i] = &value
+		case "Decimal":
+			var value duckDB.Decimal
+			valuePtrs[i] = &value
+		default:
+			panic("Unsupported type")
+		}
 	}
 
 	err := rows.Scan(valuePtrs...)
 	if err != nil {
 		return nil, err
 	}
 
-	dataRow := pgproto3.DataRow{Values: values}
-	// Convert values to text format
-	for i := range values {
-		dataRow.Values[i] = []byte(string(values[i]))
+	var values [][]byte
+	for i, valuePtr := range valuePtrs {
+		switch value := valuePtr.(type) {
+		case *int32:
+			values = append(values, []byte(strconv.Itoa(int(*value))))
+		case *int64:
+			values = append(values, []byte(strconv.Itoa(int(*value))))
+		case *string:
+			values = append(values, []byte(*value))
+		case *time.Time:
+			switch cols[i].DatabaseTypeName() {
+			case "DATE":
+				values = append(values, []byte(value.Format("2006-01-02")))
+			default:
+				panic("Unsupported type")
+			}
+		case *duckDB.Decimal:
+			float64Value := (*value).Float64()
+			values = append(values, []byte(fmt.Sprintf("%v", float64Value)))
+		default:
+			panic("Unsupported type")
+		}
 	}
+	dataRow := pgproto3.DataRow{Values: values}
 
 	return &dataRow, nil
 }