HSQL 2.2.4，错误的查询计划

Posted 2023-04-18

【中文标题】HSQL 2.2.4，错误的查询计划

【英文标题】：HSQL 2.2.4, bad query plan

【发布时间】：2011-07-18 18:04:36

【问题描述】：

为什么 IR1 需要全面扫描？

table=INTR
alias=IR1
access=FULL SCAN

IR2 不需要全面扫描：

table=INTR
alias=IR2
access=INDEX PRED

这是完全相同的连接：

EXPLAIN PLAN FOR SELECT *
FROM DTMS.INTR_SUB s
JOIN DTMS.INTR ir1 ON s.CLASS_1 = ir1.CLASS
JOIN DTMS.NDC_INDEX n1 ON ir1.KDC1 = n1.KDC1 
JOIN DTMS.INTR ir2 ON s.CLASS_2 = ir2.CLASS
JOIN DTMS.NDC_INDEX n2 ON ir2.KDC1 = n2.KDC1 
WHERE n1.NDC = 378204701 AND n2.NDC = 378204701

这是我的索引：

 s INDEX 1 CLASS_1
 s INDEX 2 CLASS_2
 ir PRIMARY KEY(KDC1,CLASS)
 ir INDEX (CLASS)

如果我禁用 s.CLASS_1 上的索引（通过添加 0）， HSQL 决定它可以为 IR1 使用相同的索引 和 IR2。

 alias=S
 access=FULL SCAN

 table=INTR
 alias=IR2
 access=INDEX PRED

 table=INTR
 alias=IR1
 access=INDEX PRED

 EXPLAIN PLAN FOR SELECT *
 FROM DTMS.INTR_SUB s
 JOIN DTMS.INTR ir1 ON s.CLASS_1+0 = ir1.CLASS
 JOIN DTMS.NDC_INDEX n1 ON ir1.KDC1 = n1.KDC1 
 JOIN DTMS.INTR ir2 ON s.CLASS_2 = ir2.CLASS
 JOIN DTMS.NDC_INDEX n2 ON ir2.KDC1 = n2.KDC1 
 WHERE n1.NDC = 378204701 AND n2.NDC = 378204701

这是架构。在数据库管理器中，我必须复制/粘贴 三者分别建表做表：

 CREATE SCHEMA DTMS AUTHORIZATION SA;

 SET SCHEMA DTMS;

 CREATE CACHED TABLE DTMS.INTR(KDC1 NUMERIC(5) NOT NULL,CLASS NUMERIC(5) NOT NULL,PRIMARY KEY(KDC1,CLASS));

 CREATE CACHED TABLE DTMS.NDC_INDEX(NDC NUMERIC(11) PRIMARY KEY,KDC1 NUMERIC(5) NOT NULL,KDC2 NUMERIC(2) NOT NULL,KDC3 NUMERIC(3) NOT NULL,ACTIVITY_CODE NUMERIC(1) NOT NULL,ROUTE_ABRV CHARACTER(2) NOT NULL);

 CREATE CACHED TABLE DTMS.INTR_SUB(CLASS_1 NUMERIC(5) NOT NULL,DURATION_1 NUMERIC(3) NOT NULL,SCHEDULE_1 NUMERIC(3) NOT NULL,ACTIVITY_CODE_1 NUMERIC(1) NOT NULL,CLASS_2 NUMERIC(5) NOT NULL,DURATION_2 NUMERIC(3) NOT NULL,SCHEDULE_2 NUMERIC(3) NOT NULL,ACTIVITY_CODE_2 NUMERIC(1) NOT NULL,ONSET_CODE NUMERIC(1) NOT NULL,SEVERITY_CODE NUMERIC(1) NOT NULL,DOC_CODE NUMERIC(1) NOT NULL,MGMT_CODE NUMERIC(1) NOT NULL,FILE_POS NUMERIC(15) NOT NULL);

 CREATE INDEX INTR_SUB_CLASS_1 ON DTMS.INTR_SUB(CLASS_1);
 CREATE INDEX INTR_SUB_CLASS_2 ON DTMS.INTR_SUB(CLASS_2);
 CREATE INDEX INTR_CLASS ON DTMS.INTR(CLASS);

【参考方案1】：

此问题已在 2.2.5 中修复，报告如下。

  ][range variable 2                                 
  join type=INNER                                    
  table=INTR                                         
  alias=IR1                                          
  access=INDEX PRED                                  

  ][range variable 4                                 
  join type=INNER                                    
  table=INTR                                         
  alias=IR2                                          
  access=INDEX PRED        

关于 DatabaseManager 的使用，您可以将整个架构连同其表和索引一起定义为单个 SQL 语句。分号仅在末尾使用。该语句完全由 DatabaseManager 执行，因为它是 SQL 中的单个 CREATE SCHEMA 语句：

CREATE SCHEMA DTMS AUTHORIZATION SA
 CREATE CACHED TABLE DTMS.INTR(KDC1 NUMERIC(5) NOT NULL,CLASS NUMERIC(5) NOT NULL,PRIMARY KEY(KDC1,CLASS))
 CREATE CACHED TABLE DTMS.NDC_INDEX(NDC NUMERIC(11) PRIMARY KEY,KDC1 NUMERIC(5) NOT NULL,KDC2 NUMERIC(2) NOT NULL,KDC3 NUMERIC(3) NOT NULL,ACTIVITY_CODE NUMERIC(1) NOT NULL,ROUTE_ABRV CHARACTER(2) NOT NULL)
 CREATE CACHED TABLE DTMS.INTR_SUB(CLASS_1 NUMERIC(5) NOT NULL,DURATION_1 NUMERIC(3) NOT NULL,SCHEDULE_1 NUMERIC(3) NOT NULL,ACTIVITY_CODE_1 NUMERIC(1) NOT NULL,CLASS_2 NUMERIC(5) NOT NULL,DURATION_2 NUMERIC(3) NOT NULL,SCHEDULE_2 NUMERIC(3) NOT NULL,ACTIVITY_CODE_2 NUMERIC(1) NOT NULL,ONSET_CODE NUMERIC(1) NOT NULL,SEVERITY_CODE NUMERIC(1) NOT NULL,DOC_CODE NUMERIC(1) NOT NULL,MGMT_CODE NUMERIC(1) NOT NULL,FILE_POS NUMERIC(15) NOT NULL)
 CREATE INDEX INTR_SUB_CLASS_1 ON DTMS.INTR_SUB(CLASS_1)
 CREATE INDEX INTR_SUB_CLASS_2 ON DTMS.INTR_SUB(CLASS_2)
 CREATE INDEX INTR_CLASS ON DTMS.INTR(CLASS);