nifi-extension-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/db/impl/OracleDatabaseAdapter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.nifi.processors.standard.db.impl;

import org.apache.commons.lang3.StringUtils;
import org.apache.nifi.processors.standard.db.ColumnDescription;
import org.apache.nifi.processors.standard.db.DatabaseAdapter;
import org.apache.nifi.processors.standard.db.TableSchema;

import java.sql.JDBCType;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import static java.sql.Types.CHAR;
import static java.sql.Types.CLOB;
import static java.sql.Types.LONGNVARCHAR;
import static java.sql.Types.LONGVARCHAR;
import static java.sql.Types.NCHAR;
import static java.sql.Types.NCLOB;
import static java.sql.Types.NVARCHAR;
import static java.sql.Types.OTHER;
import static java.sql.Types.SQLXML;
import static java.sql.Types.VARCHAR;

/**
 * A DatabaseAdapter that generates Oracle-compliant SQL.
 */
public class OracleDatabaseAdapter implements DatabaseAdapter {
    @Override
    public String getName() {
        return "Oracle";
    }

    @Override
    public String getDescription() {
        return "Generates Oracle compliant SQL";
    }

    @Override
    public String getSelectStatement(String tableName, String columnNames, String whereClause, String orderByClause, Long limit, Long offset) {
        return getSelectStatement(tableName, columnNames, whereClause, orderByClause, limit, offset, null);
    }

    @Override
    public String getSelectStatement(String tableName, String columnNames, String whereClause, String orderByClause, Long limit, Long offset, String columnForPartitioning) {
        if (StringUtils.isEmpty(tableName)) {
            throw new IllegalArgumentException("Table name cannot be null or empty");
        }

        final StringBuilder query = new StringBuilder();
        boolean nestedSelect = (limit != null || offset != null) && StringUtils.isEmpty(columnForPartitioning);
        if (nestedSelect) {
            // Need a nested SELECT query here in order to use ROWNUM to limit the results
            query.append("SELECT ");
            if (StringUtils.isEmpty(columnNames) || columnNames.trim().equals("*")) {
                query.append("*");
            } else {
                query.append(columnNames);
            }
            query.append(" FROM (SELECT a.*, ROWNUM rnum FROM (");
        }

        query.append("SELECT ");
        if (StringUtils.isEmpty(columnNames) || columnNames.trim().equals("*")) {
            query.append("*");
        } else {
            query.append(columnNames);
        }
        query.append(" FROM ");
        query.append(tableName);

        if (!StringUtils.isEmpty(whereClause)) {
            query.append(" WHERE ");
            query.append(whereClause);
            if (!StringUtils.isEmpty(columnForPartitioning)) {
                query.append(" AND ");
                query.append(columnForPartitioning);
                query.append(" >= ");
                query.append(offset != null ? offset : "0");
                if (limit != null) {
                    query.append(" AND ");
                    query.append(columnForPartitioning);
                    query.append(" < ");
                    query.append((offset == null ? 0 : offset) + limit);
                }
            }
        }
        if (!StringUtils.isEmpty(orderByClause) && StringUtils.isEmpty(columnForPartitioning)) {
            query.append(" ORDER BY ");
            query.append(orderByClause);
        }
        if (nestedSelect) {
            query.append(") a");
            long offsetVal = 0;
            if (offset != null) {
                offsetVal = offset;
            }
            if (limit != null) {
                query.append(" WHERE ROWNUM <= ");
                query.append(offsetVal + limit);
            }
            query.append(") WHERE rnum > ");
            query.append(offsetVal);
        }

        return query.toString();
    }

    @Override
    public String getTableAliasClause(String tableName) {
        return tableName;
    }

    @Override
    public List<String> getAlterTableStatements(String tableName, List<ColumnDescription> columnsToAdd, final boolean quoteTableName, final boolean quoteColumnNames) {
        StringBuilder createTableStatement = new StringBuilder();

        List<String> columnsAndDatatypes = new ArrayList<>(columnsToAdd.size());
        for (ColumnDescription column : columnsToAdd) {
            String dataType = getSQLForDataType(column.getDataType());
            StringBuilder sb = new StringBuilder()
                    .append(quoteColumnNames ? getColumnQuoteString() : "")
                    .append(column.getColumnName())
                    .append(quoteColumnNames ? getColumnQuoteString() : "")
                    .append(" ")
                    .append(dataType);
            columnsAndDatatypes.add(sb.toString());
        }

        createTableStatement.append("ALTER TABLE ")
                .append(quoteTableName ? getTableQuoteString() : "")
                .append(tableName)
                .append(quoteTableName ? getTableQuoteString() : "")
                .append(" ADD (")
                .append(String.join(", ", columnsAndDatatypes))
                .append(") ");

        return Collections.singletonList(createTableStatement.toString());
    }

    @Override
    public String getSQLForDataType(int sqlType) {
        switch (sqlType) {
            case Types.DOUBLE:
                return "DOUBLE PRECISION";
            case CHAR:
            case LONGNVARCHAR:
            case LONGVARCHAR:
            case NCHAR:
            case NVARCHAR:
            case VARCHAR:
            case CLOB:
            case NCLOB:
            case OTHER:
            case SQLXML:
                // Must have a max length specified (the Oracle docs say 2000), and use VARCHAR2 instead of VARCHAR for consistent comparison semantics
                return "VARCHAR2(2000)";
            default:
                return JDBCType.valueOf(sqlType).getName();
        }
    }

    @Override
    public boolean supportsCreateTableIfNotExists() {
        return true;
    }

    /**
     * Generates a CREATE TABLE statement using the specified table schema
     * @param tableSchema The table schema including column information
     * @param quoteTableName Whether to quote the table name in the generated DDL
     * @param quoteColumnNames Whether to quote column names in the generated DDL
     * @return A String containing DDL to create the specified table
     */
    @Override
    public String getCreateTableStatement(TableSchema tableSchema, boolean quoteTableName, boolean quoteColumnNames) {
        StringBuilder createTableStatement = new StringBuilder()
                .append("DECLARE\n\tsql_stmt long;\nBEGIN\n\tsql_stmt:='CREATE TABLE ")
                .append(generateTableName(quoteTableName, tableSchema.getCatalogName(), tableSchema.getSchemaName(), tableSchema.getTableName(), tableSchema))
                .append(" (");

        List<ColumnDescription> columns = tableSchema.getColumnsAsList();
        Set<String> primaryKeyColumnNames = tableSchema.getPrimaryKeyColumnNames();
        for (int i = 0; i < columns.size(); i++) {
            ColumnDescription column = columns.get(i);
            createTableStatement
                    .append((i != 0) ? ", " : "")
                    .append(quoteColumnNames ? getColumnQuoteString() : "")
                    .append(column.getColumnName())
                    .append(quoteColumnNames ? getColumnQuoteString() : "")
                    .append(" ")
                    .append(getSQLForDataType(column.getDataType()))
                    .append(column.isNullable() ? "" : " NOT NULL")
                    .append(primaryKeyColumnNames != null && primaryKeyColumnNames.contains(column.getColumnName()) ? " PRIMARY KEY" : "");
        }

        createTableStatement
                .append(")';\nEXECUTE IMMEDIATE sql_stmt;\nEXCEPTION\n\tWHEN OTHERS THEN\n\t\tIF SQLCODE = -955 THEN\n\t\t\t")
                .append("NULL;\n\t\tELSE\n\t\t\tRAISE;\n\t\tEND IF;\nEND;");

        return createTableStatement.toString();
    }
}