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db.sql.api.impl.tookit.SQLOptimizeUtils Maven / Gradle / Ivy
package db.sql.api.impl.tookit;
import db.sql.api.Cmd;
import db.sql.api.DbType;
import db.sql.api.SqlBuilderContext;
import db.sql.api.cmd.JoinMode;
import db.sql.api.cmd.basic.CmdList;
import db.sql.api.cmd.basic.SQL1;
import db.sql.api.cmd.basic.UnionsCmdLists;
import db.sql.api.cmd.executor.IQuery;
import db.sql.api.cmd.struct.Joins;
import db.sql.api.cmd.struct.query.IUnion;
import db.sql.api.cmd.struct.query.Unions;
import db.sql.api.impl.cmd.basic.CountAll;
import db.sql.api.impl.cmd.dbFun.Count;
import db.sql.api.impl.cmd.struct.Join;
import db.sql.api.impl.cmd.struct.Limit;
import db.sql.api.impl.cmd.struct.query.GroupBy;
import db.sql.api.impl.cmd.struct.query.OrderBy;
import db.sql.api.impl.cmd.struct.query.Select;
import db.sql.api.tookit.CmdUtils;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
/**
* 优化sql工具
* 优化join
* 优化count的order by 和 left join
*/
public final class SQLOptimizeUtils {
public static int getStringBuilderCapacity(List cmds) {
return 200;
}
private static boolean isCanRemoveLeftJoin(Join current, List joinList, boolean forClass, Map classCmdMap) {
for (Join j : joinList) {
if (j == current) {
continue;
}
if (j.getOn().contain(current.getSecondTable())) {
return false;
}
}
for (Map.Entry entry : classCmdMap.entrySet()) {
Class c = entry.getKey();
//前面已经检测了
if (c == Joins.class) {
continue;
}
if (forClass && c == Select.class) {
Select select = (Select) entry.getValue();
if (select.isDistinct()) {
if (select.contain(current.getSecondTable())) {
//包含在distinct中 不行
return false;
}
}
continue;
}
if (entry.getValue().contain(current.getSecondTable())) {
return false;
}
}
return true;
}
private static boolean removeLeftJoin(List joinList, boolean forCount, Map classCmdMap) {
boolean hasLeftJoin = false;
for (Join join : joinList) {
if (join.getMode() == JoinMode.LEFT) {
hasLeftJoin = true;
break;
}
}
if (!hasLeftJoin) {
//未包含left join 不优化
return false;
}
//循环中是否优化过
boolean removeOne = false;
int size = joinList.size();
while (true) {
boolean remove = false;
for (int i = size - 1; i >= 0; i--) {
//从后面扫描 因为从习惯上 最后一个是最容易被优化的
Join join = joinList.get(i);
if (join.getMode() == JoinMode.LEFT) {
//判断是否能删除
if (isCanRemoveLeftJoin(join, joinList, forCount, classCmdMap)) {
removeOne = true;
remove = true;
joinList.remove(i);
--size;
break;
}
}
}
if (!remove) {
//假如一个都没有优化，说明无法再优化了
break;
}
}
return removeOne;
}
private static void optimizedCmdList(DbType dbType, Map classCmdMap, boolean forCount, boolean optimizeOrderBy, boolean optimizeJoins, boolean isUnionQuery) {
if (forCount) {
if (!isUnionQuery) {
//非union查询 可删除分页
classCmdMap.remove(Limit.class);
}
}
if (optimizeOrderBy) {
if (isUnionQuery) {
//union查询 没有分页 可删除order by
if (!classCmdMap.containsKey(Limit.class)) {
classCmdMap.remove(OrderBy.class);
}
} else {
//非union查询 可删除order by
classCmdMap.remove(OrderBy.class);
}
}
if (optimizeJoins) {
//删选组件
Joins joins = (Joins) classCmdMap.get(Joins.class);
if (Objects.nonNull(joins)) {
List joinList = new ArrayList<>(joins.getJoins());
if (removeLeftJoin(joinList, forCount, classCmdMap)) {
if (joinList.isEmpty()) {
classCmdMap.remove(Joins.class);
} else {
classCmdMap.put(Joins.class, new Joins(joinList));
}
}
}
}
Unions unions = (Unions) classCmdMap.get(Unions.class);
if (Objects.nonNull(unions) && (optimizeOrderBy || optimizeJoins)) {
// 优化union
// 无法优化 select 和 order by
List unionList = unions.getUnions();
int size = unionList.size();
List cmdListList = new ArrayList<>(size);
for (IUnion union : unionList) {
Map unionCmdClassMap = new HashMap<>();
List unionCmdList = union.getUnionQuery().cmds();
for (Cmd unionCmd : unionCmdList) {
unionCmdClassMap.put(unionCmd.getClass(), unionCmd);
}
optimizedCmdList(dbType, unionCmdClassMap, false, optimizeOrderBy, optimizeJoins, true);
unionCmdList = (List) unionCmdClassMap.values().stream().sorted(union.getUnionQuery().comparator()).collect(Collectors.toList());
CmdList cmdList = new CmdList(union.getOperator(), unionCmdList);
cmdListList.add(cmdList);
}
classCmdMap.remove(Unions.class);
classCmdMap.put(UnionsCmdLists.class, new UnionsCmdLists(cmdListList));
}
Select select = (Select) classCmdMap.get(Select.class);
if (forCount && !isUnionQuery && !select.isDistinct()) {
Select newSelect;
if (dbType == DbType.ORACLE) {
if (classCmdMap.containsKey(GroupBy.class)) {
//ORACLE 有group时 无法支持 select 1
newSelect = select;
} else {
newSelect = new Select().select(SQL1.INSTANCE);
}
} else {
newSelect = new Select().select(SQL1.INSTANCE);
}
classCmdMap.put(Select.class, newSelect);
}
}
/**
* 获取优化后的查询
* 只优化left joins
*
* @param query 查询语句
* @param context 构建SQL上下文
* @return
*/
public static StringBuilder getOptimizedSql(IQuery query, SqlBuilderContext context) {
if (query.getJoins() == null) {
return query.sql(context, new StringBuilder(getStringBuilderCapacity(query.cmds())));
}
Map classCmdMap = new HashMap<>();
List cmdList = query.cmds();
int size = cmdList.size();
for (Cmd cmd : cmdList) {
classCmdMap.put(cmd.getClass(), cmd);
}
optimizedCmdList(context.getDbType(), classCmdMap, false, false, true, classCmdMap.containsKey(Unions.class));
cmdList = (List) classCmdMap.values().stream().sorted(query.comparator()).collect(Collectors.toList());
return CmdUtils.join(context, new StringBuilder(getStringBuilderCapacity(cmdList)), cmdList);
}
/**
* 从一个query里获取count SQL
*
* @param query 查询语句
* @param context 构建SQL上下文
* @param optimize 是否优化
* @return SQL StringBuilder
*/
public static StringBuilder getCountSqlFromQuery(IQuery query, SqlBuilderContext context, boolean optimize) {
if (!optimize) {
return SQLOptimizeUtils.getOptimizedCountSql(query, context, true, false);
// if (context.getDbType() == DbType.SQL_SERVER || context.getDbType() == DbType.ORACLE) {
// //需要去掉order by
// return SQLOptimizeUtils.getOptimizedCountSql(query, context, true, false);
// }
// //不优化直接包裹一层
// return new StringBuilder("SELECT COUNT(*) FROM (").append(CmdUtils.join(context, new StringBuilder(getStringBuilderCapacity(query.cmds())), query.sortedCmds())).append(") T");
}
return getOptimizedCountSql(query, context);
}
/**
* 获取优化后的count sql
*
* @param query 查询语句
* @param context 构建SQL上下文
* @return SQL StringBuilder
*/
public static StringBuilder getOptimizedCountSql(IQuery query, SqlBuilderContext context, boolean optimizeOrderBy, boolean optimizeJoins) {
Map classCmdMap = new HashMap<>();
List cmdList = query.cmds();
int size = cmdList.size();
for (Cmd cmd : cmdList) {
classCmdMap.put(cmd.getClass(), cmd);
}
optimizedCmdList(context.getDbType(), classCmdMap, true, optimizeOrderBy, optimizeJoins, classCmdMap.containsKey(Unions.class));
boolean needWarp = false;
if (classCmdMap.containsKey(Unions.class) || classCmdMap.containsKey(UnionsCmdLists.class)) {
//说明包含union查询
needWarp = true;
} else if (classCmdMap.containsKey(GroupBy.class)) {
//包含分组查询
needWarp = true;
}
if (!needWarp) {
Select select = (Select) classCmdMap.get(Select.class);
Select newSelect = new Select();
if (select.isDistinct()) {
newSelect.select(new Count(select));
} else {
newSelect.select(CountAll.INSTANCE);
}
classCmdMap.put(Select.class, newSelect);
}
cmdList = (List) classCmdMap.values().stream().sorted(query.comparator()).collect(Collectors.toList());
if (needWarp) {
return new StringBuilder("SELECT COUNT(*) FROM (").append(CmdUtils.join(context, new StringBuilder(getStringBuilderCapacity(cmdList)), cmdList)).append(") T");
}
return CmdUtils.join(context, new StringBuilder(getStringBuilderCapacity(cmdList)), cmdList);
}
/**
* 获取优化后的count sql
*
* @param query 查询语句
* @param context 构建SQL上下文
* @return SQL StringBuilder
*/
public static StringBuilder getOptimizedCountSql(IQuery query, SqlBuilderContext context) {
return getOptimizedCountSql(query, context, true, true);
}
}
