feat: refactor column type handling and streamline database column queries
This commit is contained in:
279
cmd/go_migrate/inspect-columns.go
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279
cmd/go_migrate/inspect-columns.go
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@@ -0,0 +1,279 @@
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package main
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import (
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"context"
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"database/sql"
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"errors"
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"fmt"
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"strings"
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"sync"
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"time"
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"github.com/jackc/pgx/v5/pgxpool"
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_ "github.com/microsoft/go-mssqldb"
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log "github.com/sirupsen/logrus"
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)
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func GetUnifiedType(systemType string) string {
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systemType = strings.ToLower(systemType)
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if systemType == "varchar" || systemType == "char" || systemType == "nvarchar" || systemType == "nchar" || systemType == "text" || systemType == "ntext" {
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return "STRING"
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}
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if systemType == "int" || systemType == "int4" || systemType == "integer" || systemType == "smallint" || systemType == "int2" || systemType == "bigint" || systemType == "int8" || systemType == "tinyint" {
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return "INTEGER"
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}
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if systemType == "decimal" || systemType == "numeric" {
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return "DECIMAL"
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}
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if systemType == "float" || systemType == "real" || systemType == "double precision" {
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return "FLOAT"
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}
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if systemType == "bit" || systemType == "boolean" {
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return "BOOLEAN"
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}
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if systemType == "date" {
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return "DATE"
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}
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if systemType == "time" || systemType == "time without time zone" {
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return "TIME"
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}
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if systemType == "datetime" || systemType == "datetime2" || systemType == "timestamp" || systemType == "timestamptz" || systemType == "timestamp with time zone" {
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return "TIMESTAMP"
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}
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if systemType == "binary" || systemType == "varbinary" || systemType == "image" || systemType == "bytea" {
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return "BINARY"
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}
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if systemType == "uniqueidentifier" || systemType == "uuid" {
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return "UUID"
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}
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if systemType == "json" {
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return "JSON"
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}
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if systemType == "geometry" || systemType == "geography" {
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return "GEOMETRY"
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}
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return strings.ToUpper(systemType)
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}
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func MapPostgresColumn(column ColumnType, maxLength *int64, precision *int64, scale *int64) ColumnType {
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stringTypes := map[string]bool{
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"varchar": true, "char": true, "character": true, "text": true, "character varying": true,
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}
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decimalTypes := map[string]bool{
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"decimal": true, "numeric": true,
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}
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if stringTypes[column.systemType] {
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if maxLength != nil {
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column.maxLength = *maxLength
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column.hasMaxLength = true
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} else {
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column.maxLength = -1
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column.hasMaxLength = false
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}
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column.hasPrecisionScale = false
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column.precision = -1
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column.scale = -1
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} else if decimalTypes[column.systemType] {
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column.hasMaxLength = false
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column.maxLength = -1
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if precision != nil && scale != nil {
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column.precision = *precision
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column.scale = *scale
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column.hasPrecisionScale = true
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} else {
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column.precision = -1
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column.scale = -1
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column.hasPrecisionScale = false
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}
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} else {
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column.hasMaxLength = false
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column.maxLength = -1
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column.hasPrecisionScale = false
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column.precision = -1
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column.scale = -1
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}
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column.unifiedType = GetUnifiedType(column.systemType)
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return column
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}
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func GetColumnTypesPostgres(db *pgxpool.Pool, migrationJob MigrationJob) ([]ColumnType, error) {
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query := `
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SELECT
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c.column_name AS name,
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c.data_type AS user_type,
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c.udt_name AS system_type,
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(CASE WHEN c.is_nullable = 'YES' THEN TRUE ELSE FALSE END) AS nullable,
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c.character_maximum_length AS max_length,
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c.numeric_precision AS precision,
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c.numeric_scale AS scale
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FROM information_schema.columns c
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WHERE c.table_schema = $1 AND c.table_name = $2
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ORDER BY c.ordinal_position;
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`
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ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
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defer cancel()
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rows, err := db.Query(ctx, query, migrationJob.Schema, migrationJob.Table)
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if err != nil {
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return nil, fmt.Errorf("Error querying column types: %w", err)
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}
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defer rows.Close()
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var colTypes []ColumnType
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for rows.Next() {
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var column ColumnType
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var scanMaxLength *int64
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var scanPrecision *int64
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var scanScale *int64
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if err := rows.Scan(
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&column.name,
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&column.userType,
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&column.systemType,
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&column.nullable,
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&scanMaxLength,
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&scanPrecision,
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&scanScale,
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); err != nil {
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return nil, fmt.Errorf("Error scanning column type results: %w", err)
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}
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colTypes = append(colTypes, MapPostgresColumn(column, scanMaxLength, scanPrecision, scanScale))
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}
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return colTypes, nil
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}
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func MapMssqlColumn(column ColumnType) ColumnType {
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stringTypes := map[string]bool{
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"varchar": true, "char": true, "nvarchar": true, "nchar": true, "text": true, "ntext": true,
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}
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decimalTypes := map[string]bool{
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"decimal": true, "numeric": true,
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}
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if stringTypes[column.systemType] {
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column.hasMaxLength = true
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if column.systemType == "nvarchar" || column.systemType == "nchar" {
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if column.maxLength > 0 {
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column.maxLength = column.maxLength / 2
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}
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}
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column.hasPrecisionScale = false
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column.precision = -1
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column.scale = -1
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} else if decimalTypes[column.systemType] {
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column.hasMaxLength = false
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column.maxLength = -1
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column.hasPrecisionScale = true
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} else {
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column.hasMaxLength = false
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column.maxLength = -1
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column.hasPrecisionScale = false
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column.precision = -1
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column.scale = -1
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}
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column.unifiedType = GetUnifiedType(column.systemType)
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return column
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}
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func GetColumnTypesMssql(db *sql.DB, migrationJob MigrationJob) ([]ColumnType, error) {
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query := `
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SELECT
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c.name AS name,
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t.name AS user_type,
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CASE WHEN t.is_user_defined = 0 THEN t.name ELSE bt.name END AS system_type,
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c.is_nullable AS nullable,
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c.max_length AS max_length,
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c.precision AS precision,
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c.scale AS scale
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FROM sys.columns c
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JOIN sys.types t ON c.user_type_id = t.user_type_id
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LEFT JOIN sys.types bt ON t.is_user_defined = 1 AND bt.user_type_id = t.system_type_id
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JOIN sys.tables st ON c.object_id = st.object_id
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JOIN sys.schemas s ON st.schema_id = s.schema_id
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WHERE s.name = @schema AND st.name = @table
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ORDER BY c.column_id;
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`
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ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
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defer cancel()
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rows, err := db.QueryContext(ctx, query, sql.Named("schema", migrationJob.Schema), sql.Named("table", migrationJob.Table))
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if err != nil {
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return nil, fmt.Errorf("Error querying column types: %w", err)
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}
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defer rows.Close()
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var colTypes []ColumnType
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for rows.Next() {
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var column ColumnType
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if err := rows.Scan(
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&column.name,
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&column.userType,
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&column.systemType,
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&column.nullable,
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&column.maxLength,
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&column.precision,
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&column.scale,
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); err != nil {
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return nil, fmt.Errorf("Error scanning column type results: %W", err)
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}
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colTypes = append(colTypes, MapMssqlColumn(column))
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}
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return colTypes, nil
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}
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func GetColumnTypes(sourceDb *sql.DB, targetDb *pgxpool.Pool, migrationJob MigrationJob) ([]ColumnType, []ColumnType, error) {
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var sourceDbErr error
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var targetDbErr error
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var sourceColTypes []ColumnType
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var targetColTypes []ColumnType
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var wg sync.WaitGroup
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wg.Go(func() {
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sourceColTypes, sourceDbErr = GetColumnTypesMssql(sourceDb, migrationJob)
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if sourceDbErr != nil {
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log.Error("Error (sourceDb): ", sourceDbErr)
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}
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})
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wg.Go(func() {
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targetColTypes, targetDbErr = GetColumnTypesPostgres(targetDb, migrationJob)
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if targetDbErr != nil {
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log.Error("Error (targetDb): ", targetDbErr)
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}
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})
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wg.Wait()
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if sourceDbErr != nil || targetDbErr != nil {
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return nil, nil, errors.New("Error querying column types")
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}
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return sourceColTypes, targetColTypes, nil
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}
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