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[SPARK-37452][SQL][3.1] Char and Varchar break backward compatibility between v3.1 and v2 #34736

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[SPARK-37452][SQL][3.1] Char and Varchar break backward compatibility between v3.1 and v2 #34736

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[SPARK-37452][SQL][BACKPORT][3.1] Char and Varchar break backward com…
yaooqinn Nov 29, 2021
efe00f7
[SPARK-37452][SQL][BACKPORT][3.1] Char and Varchar break backward com…
yaooqinn Nov 29, 2021
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19 changes: 13 additions & 6 deletions sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveExternalCatalog.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ import org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException
import org.apache.spark.sql.catalyst.catalog._
import org.apache.spark.sql.catalyst.catalog.ExternalCatalogUtils._
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.util.{CaseInsensitiveMap, DateTimeUtils}
import org.apache.spark.sql.catalyst.util.{CaseInsensitiveMap, CharVarcharUtils, DateTimeUtils}
import org.apache.spark.sql.execution.command.DDLUtils
import org.apache.spark.sql.execution.datasources.{PartitioningUtils, SourceOptions}
import org.apache.spark.sql.hive.client.HiveClient
Expand Down Expand Up @@ -429,12 +429,17 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
val properties = new mutable.HashMap[String, String]

properties.put(CREATED_SPARK_VERSION, table.createVersion)

// This is for backward compatibility to Spark 2 to read tables with char/varchar created by
// Spark 3.1. At read side, we will restore a table schema from its properties. So, we need to
// clear the `varchar(n)` and `char(n)` and replace them with `string` as Spark 2 does not have
// a type mapping for them in `DataType.nameToType`.
// See `restoreHiveSerdeTable` for example.
val newSchema = CharVarcharUtils.replaceCharVarcharWithStringInSchema(schema)
// Serialized JSON schema string may be too long to be stored into a single metastore table
// property. In this case, we split the JSON string and store each part as a separate table
// property.
val threshold = conf.get(SCHEMA_STRING_LENGTH_THRESHOLD)
val schemaJsonString = schema.json
val schemaJsonString = newSchema.json
// Split the JSON string.
val parts = schemaJsonString.grouped(threshold).toSeq
properties.put(DATASOURCE_SCHEMA_NUMPARTS, parts.size.toString)
Expand Down Expand Up @@ -745,7 +750,8 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
// If this is a view created by Spark 2.2 or higher versions, we should restore its schema
// from table properties.
if (table.properties.contains(DATASOURCE_SCHEMA_NUMPARTS)) {
table = table.copy(schema = getSchemaFromTableProperties(table))
val newSchema = CharVarcharUtils.getRawSchema(getSchemaFromTableProperties(table))
table = table.copy(schema = newSchema)
}

// No provider in table properties, which means this is a Hive serde table.
Expand Down Expand Up @@ -796,7 +802,8 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
// If this is a Hive serde table created by Spark 2.1 or higher versions, we should restore its
// schema from table properties.
if (table.properties.contains(DATASOURCE_SCHEMA_NUMPARTS)) {
val schemaFromTableProps = getSchemaFromTableProperties(table)
val schemaFromTableProps =
CharVarcharUtils.getRawSchema(getSchemaFromTableProperties(table))
val partColumnNames = getPartitionColumnsFromTableProperties(table)
val reorderedSchema = reorderSchema(schema = schemaFromTableProps, partColumnNames)

Expand Down Expand Up @@ -836,7 +843,7 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
storageWithLocation.properties.filterKeys(!HIVE_GENERATED_STORAGE_PROPERTIES(_)).toMap)
val partitionProvider = table.properties.get(TABLE_PARTITION_PROVIDER)

val schemaFromTableProps = getSchemaFromTableProperties(table)
val schemaFromTableProps = CharVarcharUtils.getRawSchema(getSchemaFromTableProperties(table))
val partColumnNames = getPartitionColumnsFromTableProperties(table)
val reorderedSchema = reorderSchema(schema = schemaFromTableProps, partColumnNames)

Expand Down