com.dimajix.flowman.jdbc.SqlDialect.scala Maven / Gradle / Ivy

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/*
 * Copyright (C) 2018 The Flowman Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.dimajix.flowman.jdbc

import java.sql.SQLException

import org.apache.spark.sql.jdbc.JdbcType

import com.dimajix.flowman.catalog.TableChange
import com.dimajix.flowman.catalog.TableIdentifier
import com.dimajix.flowman.types.FieldType


abstract class SqlDialect {
    /**
      * Check if this dialect instance can handle a certain jdbc url.
      * @param url the jdbc url.
      * @return True if the dialect can be applied on the given jdbc url.
      * @throws NullPointerException if the url is null.
      */
    def canHandle(url : String): Boolean

    /**
      * Retrieve the jdbc / sql type for a given datatype.
      * @param dt The datatype (e.g. [[org.apache.spark.sql.types.StringType]])
      * @return The new JdbcType if there is an override for this DataType
      */
    def getJdbcType(dt: FieldType): JdbcType

    /**
     * Returns the Flowman type for a given JDBC type
     * @param sqlType
     * @param precision
     * @param scale
     * @param signed
     * @return
     */
    def getFieldType(sqlType: Int, typeName:String, precision: Int, scale: Int, signed: Boolean): FieldType

    /**
      * Quotes the identifier. This is used to put quotes around the identifier in case the column
      * name is a reserved keyword, or in case it contains characters that require quotes (e.g. space).
      */
    def quoteIdentifier(colName: String): String

    /**
     * Quotes the identifier. This is used to put quotes around the identifier in case the column
     * name is a reserved keyword, or in case it contains characters that require quotes (e.g. space).
     */
    def quoteIdentifier(path: Seq[String]): String = path.map(p => quoteIdentifier(p)).mkString(".")

    /**
      * Quotes a table name including the optional database prefix
      * @param table
      * @return
      */
    def quote(table:TableIdentifier) : String

    /**
      * Escapes a String literal to be used in SQL statements
      * @param value
      * @return
      */
    def escape(value: String): String

    /**
      * Creates an SQL literal from a given value
      * @param value
      * @return
      */
    def literal(value:Any) : String

    /**
     * Returns true if an SQLException is transient and a retry of the operation may succeed
     * @param ex
     * @return
     */
    def isTransient(ex:SQLException) : Boolean

    /**
     * Returns true if the given table supports a specific table change
     * @param change
     * @return
     */
    def supportsChange(table:TableIdentifier, change:TableChange) : Boolean

    /**
     * Returns true if the SQL database supports retrieval of the exact view definition
     * @return
     */
    def supportsExactViewRetrieval : Boolean

    /**
     * Returns true if a view definition can be changed
     * @return
     */
    def supportsAlterView : Boolean

    def statement : SqlStatements
    def expr : SqlExpressions
    def command : SqlCommands
}