org.apache.spark.sql.jdbc.DerbyDialect.scala Maven / Gradle / Ivy
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.spark.sql.jdbc
import java.sql.Types
import java.util.Locale
import org.apache.spark.sql.connector.catalog.Identifier
import org.apache.spark.sql.errors.{QueryCompilationErrors, QueryExecutionErrors}
import org.apache.spark.sql.types._
private object DerbyDialect extends JdbcDialect {
override def canHandle(url: String): Boolean =
url.toLowerCase(Locale.ROOT).startsWith("jdbc:derby")
// See https://db.apache.org/derby/docs/10.15/ref/index.html
private val supportedAggregateFunctions = Set("MAX", "MIN", "SUM", "COUNT", "AVG",
"VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP")
private val supportedFunctions = supportedAggregateFunctions
override def isSupportedFunction(funcName: String): Boolean =
supportedFunctions.contains(funcName)
override def getCatalystType(
sqlType: Int, typeName: String, size: Int, md: MetadataBuilder): Option[DataType] = {
if (sqlType == Types.REAL) Option(FloatType) else None
}
override def getJDBCType(dt: DataType): Option[JdbcType] = dt match {
case StringType => Option(JdbcType("CLOB", java.sql.Types.CLOB))
case ByteType => Option(JdbcType("SMALLINT", java.sql.Types.SMALLINT))
case ShortType => Option(JdbcType("SMALLINT", java.sql.Types.SMALLINT))
case BooleanType => Option(JdbcType("BOOLEAN", java.sql.Types.BOOLEAN))
// 31 is the maximum precision and 5 is the default scale for a Derby DECIMAL
case t: DecimalType if t.precision > 31 =>
Option(JdbcType("DECIMAL(31,5)", java.sql.Types.DECIMAL))
case _ => None
}
override def isCascadingTruncateTable(): Option[Boolean] = Some(false)
// See https://db.apache.org/derby/docs/10.15/ref/rrefsqljrenametablestatement.html
override def renameTable(oldTable: Identifier, newTable: Identifier): String = {
if (!oldTable.namespace().sameElements(newTable.namespace())) {
throw QueryCompilationErrors.cannotRenameTableAcrossSchemaError()
}
// New table name restriction:
// https://db.apache.org/derby/docs/10.2/ref/rrefnewtablename.html#rrefnewtablename
s"RENAME TABLE ${getFullyQualifiedQuotedTableName(oldTable)} TO ${newTable.name()}"
}
// Derby currently doesn't support comment on table. Here is the ticket to add the support
// https://issues.apache.org/jira/browse/DERBY-7008
override def getTableCommentQuery(table: String, comment: String): String = {
throw QueryExecutionErrors.commentOnTableUnsupportedError()
}
// Derby Support 2 types of clauses for nullability constraint alteration
// columnName { SET | DROP } NOT NULL
// columnName [ NOT ] NULL
// Here we use the 2nd one
// For more information, https://db.apache.org/derby/docs/10.16/ref/rrefsqlj81859.html
override def getUpdateColumnNullabilityQuery(
tableName: String,
columnName: String,
isNullable: Boolean): String = {
val nullable = if (isNullable) "NULL" else "NOT NULL"
s"ALTER TABLE $tableName ALTER COLUMN ${quoteIdentifier(columnName)} $nullable"
}
override def getLimitClause(limit: Integer): String = {
""
}
}