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!73 分页查询优化

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Merge pull request !73 from 王帅/main
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Michael Yang 2023-06-18 13:03:34 +00:00 committed by Gitee
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8 changed files with 317 additions and 91 deletions
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36
docs/zh/others/apt.md
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@ -132,14 +132,48 @@ processor.mappersPackage = com.your-package
processor.baseMapperClass=com.domain.mapper.MyBaseMapper
```
## 实体类不在一个包中
有时候可能会遇到实体类不在同一个包中的情况，例如：
```text
com.example.entityPackage1
└─ Entity1
com.example.entityPackage2
└─ Entity2
```
此时的辅助类会生成在对应的包下，例如：
```text
com.example.entityPackage1.table
└─ Entity1TableDef
com.example.entityPackage2.table
└─ Entity2TableDef
```
但是，如果您设置了 `processor.allInTables=true` 的话，`Tables` 文件将会生成在最后一个包中，例如：
```text
com.example.entityPackage2.table
└─ Tables
```
所以，如果您的实体类在多个包中，又指定了 `processor.allInTables=true` 选项，推荐设置 `Tables` 文件的位置，例如：
```properties
processor.allInTables=true
processor.tablesPackage=com.example.entity.table
```
## 和 Lombok、Mapstruct 整合
在很多项目中，用到了 Lombok 帮我们减少代码编写，同时用到 Mapstruct 进行 bean 转换。使用到 Lombok 和 Mapstruct 时，其要求我们再 pom.xml 添加 `annotationProcessorPaths` 配置，
在很多项目中，用到了 Lombok 帮我们减少代码编写，同时用到 Mapstruct 进行 bean 转换。使用到 Lombok 和 Mapstruct 时，其要求我们再
pom.xml 添加 `annotationProcessorPaths` 配置，
此时，我们也需要把 MyBatis-Flex 的 annotation 添加到 `annotationProcessorPaths` 配置里去，如下图所示：
```xml 24,25,26,27,28
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>

77
mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java
View File

@ -20,7 +20,10 @@ import com.mybatisflex.core.field.FieldQueryBuilder;
import com.mybatisflex.core.mybatis.MappedStatementTypes;
import com.mybatisflex.core.paginate.Page;
import com.mybatisflex.core.provider.EntitySqlProvider;
import com.mybatisflex.core.query.*;
import com.mybatisflex.core.query.CPI;
import com.mybatisflex.core.query.QueryColumn;
import com.mybatisflex.core.query.QueryCondition;
import com.mybatisflex.core.query.QueryWrapper;
import com.mybatisflex.core.table.TableInfo;
import com.mybatisflex.core.table.TableInfoFactory;
import com.mybatisflex.core.util.*;
@ -667,47 +670,43 @@ public interface BaseMapper<T> {
default <R> Page<R> paginateAs(Page<R> page, QueryWrapper queryWrapper, Class<R> asType, Consumer<FieldQueryBuilder<R>>... consumers) {
List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
List<QueryOrderBy> orderBys = CPI.getOrderBys(queryWrapper);
List<Join> joins = CPI.getJoins(queryWrapper);
// 只有 totalRow 小于 0 的时候才会去查询总量
// 这样方便用户做总数缓存，而非每次都要去查询总量
// 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
if (page.getTotalRow() < 0) {
QueryWrapper countQueryWrapper = MapperUtil.optimizeCountQueryWrapper(queryWrapper);
long count = selectCountByQuery(countQueryWrapper);
page.setTotalRow(count);
}
try {
// 只有 totalRow 小于 0 的时候才会去查询总量
// 这样方便用户做总数缓存，而非每次都要去查询总量
// 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
if (page.getTotalRow() < 0) {
QueryWrapper countQueryWrapper;
if (page.isOptimizeCountSql()) {
countQueryWrapper = MapperUtil.optimizeCountQueryWrapper(queryWrapper);
} else {
countQueryWrapper = MapperUtil.rawCountQueryWrapper(queryWrapper);
}
page.setTotalRow(selectCountByQuery(countQueryWrapper));
}
if (page.isEmpty()) {
return page;
}
queryWrapper.limit(page.getOffset(), page.getPageSize());
List<R> records;
if (asType != null) {
records = selectListByQueryAs(queryWrapper, asType);
} else {
records = (List<R>) selectListByQuery(queryWrapper);
}
MapperUtil.queryFields(this, records, consumers);
page.setRecords(records);
if (page.isEmpty()) {
return page;
} finally {
// 将之前设置的 limit 清除掉
// 保险起见把重置代码放到 finally 代码块中
CPI.setLimitRows(queryWrapper, null);
CPI.setLimitOffset(queryWrapper, null);
}
//重置 selectColumns
CPI.setSelectColumns(queryWrapper, selectColumns);
//重置 orderBys
CPI.setOrderBys(queryWrapper, orderBys);
//重置 join
CPI.setJoins(queryWrapper, joins);
int offset = page.getPageSize() * (page.getPageNumber() - 1);
queryWrapper.limit(offset, page.getPageSize());
if (asType != null) {
List<R> records = selectListByQueryAs(queryWrapper, asType);
MapperUtil.queryFields(this, records, consumers);
page.setRecords(records);
} else {
List<R> records = (List<R>) selectListByQuery(queryWrapper);
MapperUtil.queryFields(this, records, consumers);
page.setRecords(records);
}
// 将之前设置的 limit 清除掉
CPI.setLimitRows(queryWrapper, null);
CPI.setLimitOffset(queryWrapper, null);
return page;
}

169
mybatis-flex-core/src/main/java/com/mybatisflex/core/paginate/IPage.java Normal file
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@ -0,0 +1,169 @@
/*
* Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
* <p>
* 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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.mybatisflex.core.paginate;
import java.io.Serializable;
import java.util.List;
/**
* 分页接口。
*
* @param <T> 数据类型
* @author 王帅
* @since 2023-06-18
*/
public interface IPage<T> extends Serializable {
/**
* 获取当前页码。
*
* @return 页码
*/
int getPageNumber();
/**
* 设置当前页码。
*
* @param pageNumber 页码
*/
void setPageNumber(int pageNumber);
/**
* 获取当前每页数据数量。
*
* @return 每页数据数量
*/
int getPageSize();
/**
* 设置当前每页数据数量。
*
* @param pageSize 每页数据数量
*/
void setPageSize(int pageSize);
/**
* 获取数据总数。
*
* @return 数据总数
*/
long getTotalRow();
/**
* 设置数据总数。
*
* @param totalRow 数据总数
*/
void setTotalRow(long totalRow);
/**
* 获取当前页的数据。
*
* @return 当前页的数据
*/
List<T> getRecords();
/**
* 设置当前页的数据。
*
* @param records 当前页的数据
*/
void setRecords(List<T> records);
/**
* 获取当前分页偏移量。
*
* @return 偏移量
*/
default int getOffset() {
return getPageSize() * (getPageNumber() - 1);
}
/**
* 是否自动优化 COUNT 查询语句（默认优化）。
*
* @return {@code true} 优化，{@code false} 不优化
*/
default boolean isOptimizeCountSql() {
return true;
}
/**
* 设置是否自动优化 COUNT 查询语句。
*
* @param optimizeCountSql 是否优化
*/
default void setOptimizeCountSql(boolean optimizeCountSql) {
// 默认总是优化
}
/**
* 获取总页数。
*
* @return 总页数
*/
default long getTotalPage() {
// 实时计算总页数
int pageSize = getPageSize();
if (pageSize == 0) {
return 0L;
}
long totalRow = getTotalRow();
long totalPage = totalRow / pageSize;
if (totalRow % pageSize != 0) {
totalPage++;
}
return totalPage;
}
/**
* 设置总页数。
*
* @param totalPage 总页数
*/
default void setTotalPage(long totalPage) {
// 总页数是实时计算的，所以这里设置了也没用。
}
/**
* 是否存在上一页。
*
* @return {@code true} 存在上一页，{@code false} 不存在上一页
*/
default boolean hasPrevious() {
return getPageNumber() > 1;
}
/**
* 是否存在下一页。
*
* @return {@code true} 存在下一页，{@code false} 不存在下一页
*/
default boolean hasNext() {
return getPageNumber() < getTotalPage();
}
/**
* 当前页是否为空。
*
* @return {@code true} 空页，{@code false} 非空页
*/
default boolean isEmpty() {
return getTotalRow() == 0 || getPageNumber() > getTotalPage();
}
}

27
mybatis-flex-core/src/main/java/com/mybatisflex/core/paginate/Page.java
View File

@ -15,13 +15,12 @@
*/
package com.mybatisflex.core.paginate;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.function.Function;
public class Page<T> implements Serializable {
public class Page<T> implements IPage<T> {
private static final long serialVersionUID = 1L;
public static final int INIT_VALUE = -1;
@ -32,6 +31,8 @@ public class Page<T> implements Serializable {
private long totalPage = INIT_VALUE;
private long totalRow = INIT_VALUE;
private boolean optimizeCountSql = true;
public static <T> Page<T> of(int pageNumber, int pageSize) {
return new Page<>(pageNumber, pageSize);
}
@ -64,10 +65,22 @@ public class Page<T> implements Serializable {
}
@Override
public boolean isOptimizeCountSql() {
return optimizeCountSql;
}
@Override
public void setOptimizeCountSql(boolean optimizeCountSql) {
this.optimizeCountSql = optimizeCountSql;
}
@Override
public List<T> getRecords() {
return records;
}
@Override
public void setRecords(List<T> records) {
if (records == null) {
records = Collections.emptyList();
@ -75,10 +88,12 @@ public class Page<T> implements Serializable {
this.records = records;
}
@Override
public int getPageNumber() {
return pageNumber;
}
@Override
public void setPageNumber(int pageNumber) {
if (pageNumber < 1) {
throw new IllegalArgumentException("pageNumber must greater than or equal 1，current value is: " + pageNumber);
@ -87,10 +102,12 @@ public class Page<T> implements Serializable {
}
@Override
public int getPageSize() {
return pageSize;
}
@Override
public void setPageSize(int pageSize) {
if (pageSize < 0) {
throw new IllegalArgumentException("pageSize must greater than or equal 0，current value is: " + pageSize);
@ -99,18 +116,22 @@ public class Page<T> implements Serializable {
this.calcTotalPage();
}
@Override
public long getTotalPage() {
return totalPage;
}
@Override
public void setTotalPage(long totalPage) {
this.totalPage = totalPage;
}
@Override
public long getTotalRow() {
return totalRow;
}
@Override
public void setTotalRow(long totalRow) {
this.totalRow = totalRow;
this.calcTotalPage();
@ -127,10 +148,12 @@ public class Page<T> implements Serializable {
}
}
@Override
public boolean isEmpty() {
return getTotalRow() == 0 || getPageNumber() > getTotalPage();
}
@Override
public boolean hasNext() {
return getTotalPage() != 0 && getPageNumber() < getTotalPage();
}

62
mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowMapper.java
View File

@ -19,7 +19,9 @@ import com.mybatisflex.core.FlexConsts;
import com.mybatisflex.core.exception.FlexExceptions;
import com.mybatisflex.core.paginate.Page;
import com.mybatisflex.core.provider.RowSqlProvider;
import com.mybatisflex.core.query.*;
import com.mybatisflex.core.query.CPI;
import com.mybatisflex.core.query.QueryColumn;
import com.mybatisflex.core.query.QueryWrapper;
import com.mybatisflex.core.util.CollectionUtil;
import com.mybatisflex.core.util.MapperUtil;
import com.mybatisflex.core.util.StringUtil;
@ -431,47 +433,39 @@ public interface RowMapper {
* @return
*/
default Page<Row> paginate(String schema, String tableName, Page<Row> page, QueryWrapper queryWrapper) {
try {
CPI.setFromIfNecessary(queryWrapper, schema, tableName);
CPI.setFromIfNecessary(queryWrapper, schema, tableName);
// 只有 totalRow 小于 0 的时候才会去查询总量
// 这样方便用户做总数缓存，而非每次都要去查询总量
// 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
if (page.getTotalRow() < 0) {
QueryWrapper countQueryWrapper;
if (page.isOptimizeCountSql()) {
countQueryWrapper = MapperUtil.optimizeCountQueryWrapper(queryWrapper);
} else {
countQueryWrapper = MapperUtil.rawCountQueryWrapper(queryWrapper);
}
page.setTotalRow(selectCountByQuery(schema, tableName, countQueryWrapper));
}
List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
if (page.isEmpty()) {
return page;
}
List<QueryOrderBy> orderBys = CPI.getOrderBys(queryWrapper);
queryWrapper.limit(page.getOffset(), page.getPageSize());
List<Join> joins = CPI.getJoins(queryWrapper);
page.setRecords(selectListByQuery(schema, tableName, queryWrapper));
// 只有 totalRow 小于 0 的时候才会去查询总量
// 这样方便用户做总数缓存，而非每次都要去查询总量
// 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
if (page.getTotalRow() < 0) {
QueryWrapper countQueryWrapper = MapperUtil.optimizeCountQueryWrapper(queryWrapper);
long count = selectCountByQuery(schema, tableName, countQueryWrapper);
page.setTotalRow(count);
}
if (page.isEmpty()) {
return page;
} finally {
// 将之前设置的 limit 清除掉
// 保险起见把重置代码放到 finally 代码块中
CPI.setLimitRows(queryWrapper, null);
CPI.setLimitOffset(queryWrapper, null);
}
//重置 selectColumns
CPI.setSelectColumns(queryWrapper, selectColumns);
//重置 orderBys
CPI.setOrderBys(queryWrapper, orderBys);
//重置 join
CPI.setJoins(queryWrapper, joins);
int offset = page.getPageSize() * (page.getPageNumber() - 1);
queryWrapper.limit(offset, page.getPageSize());
List<Row> records = selectListByQuery(schema, tableName, queryWrapper);
page.setRecords(records);
// 将之前设置的 limit 清除掉
CPI.setLimitRows(queryWrapper, null);
CPI.setLimitOffset(queryWrapper, null);
return page;
}
}

25
mybatis-flex-core/src/main/java/com/mybatisflex/core/util/MapperUtil.java
View File

@ -42,7 +42,7 @@ public class MapperUtil {
*
* <p><pre>
* {@code
* SELECT COUNT(*) AS `total` FROM ( ...用户构建的 SQL 语句... );
* SELECT COUNT(*) AS `total` FROM ( ...用户构建的 SQL 语句... ) AS `t`;
* }
* </pre>
*
@ -58,22 +58,25 @@ public class MapperUtil {
* 优化 COUNT 查询语句。
*/
public static QueryWrapper optimizeCountQueryWrapper(QueryWrapper queryWrapper) {
List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
List<QueryColumn> groupByColumns = CPI.getGroupByColumns(queryWrapper);
// 对克隆对象进行操作，不影响原来的 QueryWrapper 对象
QueryWrapper clone = queryWrapper.clone();
// 将最后面的 order by 移除掉
CPI.setOrderBys(clone, null);
// 获取查询列和分组列，用于判断是否进行优化
List<QueryColumn> selectColumns = CPI.getSelectColumns(clone);
List<QueryColumn> groupByColumns = CPI.getGroupByColumns(clone);
// 如果有 distinct 语句或者 group by 语句则不优化
// 这种一旦优化了就会造成 count 语句查询出来的值不对
if (hasDistinct(selectColumns) || hasGroupBy(groupByColumns)) {
return rawCountQueryWrapper(queryWrapper);
return rawCountQueryWrapper(clone);
}
// 判断能不能清除 join 语句
if (canClearJoins(queryWrapper)) {
CPI.setJoins(queryWrapper, null);
if (canClearJoins(clone)) {
CPI.setJoins(clone, null);
}
// 最后将最后面的 order by 移除掉
// 将 select 里面的列换成 COUNT(*) AS `total` 就好了
CPI.setOrderBys(queryWrapper, null);
CPI.setSelectColumns(queryWrapper, Collections.singletonList(count().as("total")));
return queryWrapper;
// 将 select 里面的列换成 COUNT(*) AS `total`
CPI.setSelectColumns(clone, Collections.singletonList(count().as("total")));
return clone;
}
private static boolean hasDistinct(List<QueryColumn> selectColumns) {

7
mybatis-flex-spring-boot-starter/src/main/java/com/mybatisflex/spring/boot/ConditionalOnMybatisFlexDatasource.java
View File

@ -19,6 +19,8 @@ import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.Conditional;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.env.*;
import org.springframework.core.type.AnnotatedTypeMetadata;
@ -34,6 +36,7 @@ import java.util.Iterator;
@Conditional(ConditionalOnMybatisFlexDatasource.OnMybatisFlexDataSourceCondition.class)
public @interface ConditionalOnMybatisFlexDatasource {
@Order(Ordered.HIGHEST_PRECEDENCE + 40)
class OnMybatisFlexDataSourceCondition extends SpringBootCondition {
@Override
@ -44,8 +47,8 @@ public @interface ConditionalOnMybatisFlexDatasource {
Iterator<PropertySource<?>> it = propertySources.stream().iterator();
while (it.hasNext()) {
PropertySource<?> ps = it.next();
if (ps instanceof MapPropertySource) {
for (String propertyName : ((MapPropertySource) ps).getSource().keySet()) {
if (ps instanceof EnumerablePropertySource) {
for (String propertyName : ((EnumerablePropertySource<?>) ps).getPropertyNames()) {
if (propertyName.startsWith("mybatis-flex.datasource.")) {
return ConditionOutcome.match();
}

5
mybatis-flex-test/mybatis-flex-spring-boot-test/src/test/java/com/mybatisflex/test/mapper/UserMapperTest.java
View File

@ -143,10 +143,11 @@ class UserMapperTest {
.leftJoin(USER_ROLE).as("ur").on(USER_ROLE.USER_ID.eq(USER.USER_ID))
.leftJoin(ROLE).as("r").on(USER_ROLE.ROLE_ID.eq(ROLE.ROLE_ID));
System.err.println(queryWrapper.toSQL());
Page<UserVO> page;
Page<UserVO> page = Page.of(1, 1);
page.setOptimizeCountSql(false);
int pageNumber = 0;
do {
page = Page.of(++pageNumber, 1);
page.setPageNumber(page.getPageNumber() + 1);
page = userMapper.paginateAs(page, queryWrapper, UserVO.class);
System.err.println(page);
} while (page.hasNext());