MariaDbDialect.java
/*
** Module : MariaDbDialect.java
** Abstract : Concrete implementation of Dialect for a strict(er) MariaDb backend.
**
** Copyright (c) 2022-2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description---------------------------------------
** 001 OM 20220715 Created initial version with minimal support.
** IAS 20220816 Added getScriptRunner() method.
** OM 20220911 Fixed datetime(-tz) datatype to include the second fractions.
** IAS 20220913 Re-work processing of UDFs errors/warnings.
** OM 20220914 Use MAX-WIDTH to generate custom sized varchar columns.
** OM 20220922 Validate the parameters for sequence definitions.
** OM 20221012 Fixed regression (invalid sort criteria) in previous commit.
** OM 20221018 Extracted common code to MariaDbLenientDialect super class.
** OM 20230131 Code cleanup.
** 002 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
** 003 DDF 20240205 Non null fields should not augment __null when creating an index.
** DDF 20240209 Mandatory column should not generate a computed column.
** DDF 20240625 Fix number of expressions in orderByNulls().
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
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*/
package com.goldencode.p2j.persist.dialect;
import com.goldencode.p2j.util.logging.*;
import java.util.*;
/**
* Extends abstract {@link Dialect} for an MariaDb/MySql backend.
*/
public class MariaDbDialect
extends MariaDbLenientDialect
{
/** The id of this dialect variant as a string. */
public static final String DIALECT_ID = "mariadb";
/** Logger */
private static final CentralLogger LOG = CentralLogger.get(MariaDbDialect.class.getName());
/**
* Get dialect id.
*
* @return the id of the dialect.
*/
@Override
public String id()
{
return MariaDbDialect.DIALECT_ID;
}
/**
* Get a collection of reserved keywords specific to this dialect.
* <p>
* The {@link com.goldencode.p2j.convert.NameConverter} uses thes list to create an exclusion
* list of names so there will not be schema collisions with identifiers (tables, fields) from
* the generated schema.
*
* @return A list with MariaDb reserved keywords.
*
* @see <a href="https://msdn.microsoft.com/en-us/library/ms189822%28v=sql.110%29.aspx">
* https://msdn.microsoft.com/en-us/library/ms189822%28v=sql.110%29.aspx</a>
*/
public static List<String> getReservedKeywords()
{
return MariaDbLenientDialect.getReservedKeywords();
}
/**
* MariaDb requires injecting computed columns for indexed fields due to lack of "nulls last" feature.
* There is a combinations of factors: the indexes cannot be defined on expressions, but we can create
* 'generated' columns which can be used as index components.
*
* @return {@code true}.
*/
@Override
public boolean injectComputedColumns()
{
return true;
}
/**
* Writes the declaration of a computed column to a {@code StringBuilder} based on its name, type, scale,
* and case-sensitiveness.
* <p>
* This dialect uses the computed columns for all columns which are components of an index in order to
* implement 'nulls last' idiom. It writes the computed column as:
* {@code "<name>__null boolean generated always as (<name> is null) virtual"}
* <p>
* <b>Note:</b><br>
* Improvement: if the field/column is mandatory, this augmentation is NOT necessary.
*
* @param name
* The original column name.
* @param type
* The original column type.
* @param scale
* The optional scale, if needed.
* @param cs
* The case-sensitiveness.
* @param mandatory
* If the field is not-null.
*
* @return The declaration of the computed column(s).
*/
@Override
public String getComputedColumnString(String name, String type, int scale, boolean cs, boolean mandatory)
{
if (mandatory)
{
return null;
}
return name + "__null boolean generated always as (" + name + " is null) virtual";
}
/**
* Determine if the sort component or index needs to be augmented with a NULLS FIRST/LAST option and
* add the required expression(s) as needed by this dialect.
*
* @param sb
* The {@code StringBuilder} which contains the SQL statement to be built.
* @param expression
* The field name (or expression) which is the current criterion to be augmented.
* @param field
* The field name which is the base of the previous parameter (possible {@code null}).
* @param asc
* The sort direction.
* @param forceAsc
* If {@code true}, force the insertion of the default {@code asc} direction.
* @param mandatory
* {@code true} if the field is already non-null, in which case it is not
* augmented with __null, {@code false} otherwise.
*
* @return the number of expressions which were added to the string builder.
*/
@Override
public int orderByNulls(StringBuilder sb,
String expression,
String field,
boolean asc,
boolean forceAsc,
boolean mandatory)
{
if (!mandatory)
{
sb.append(field != null ? field : expression).append("__null");
if (!asc)
{
sb.append(" desc");
}
else if (forceAsc)
{
sb.append(" asc");
}
sb.append(",");
return 1 + super.orderByNulls(sb, expression, null, asc, forceAsc, mandatory);
}
return super.orderByNulls(sb, expression, null, asc, forceAsc, mandatory);
}
/**
* Get the logger specific to this MariaDb dialect variant.
*
* @return the logger specific to this MariaDb dialect variant.
*/
@Override
protected CentralLogger getLog()
{
return LOG;
}
}