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[Feature]Support SELECT Optimizer Hints SET_VAR (#4504)

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This commit is contained in:
xueyan.li
2020-09-06 20:27:53 +08:00
committed by GitHub
parent 03d9f6d8b4
commit bcb443fb63
8 changed files with 112 additions and 6 deletions
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12
docs/en/administrator-guide/variables.md
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@ -85,6 +85,18 @@ SET exec_mem_limit = 10 * 1024 * 1024 * 1024;
SET forward_to_master = concat('tr', 'u', 'e');
```
### Set variables in the query statement
In some scenarios, we may need to set variables specifically for certain queries.
The SET_VAR hint sets the session value of a system variable temporarily (for the duration of a single statement). Examples:
```
SELECT /*+ SET_VAR(exec_mem_limit = 8589934592) */ name FROM people ORDER BY name;
SELECT /*+ SET_VAR(query_timeout = 1) */ sleep(3);
```
Note that the comment must start with /*+ and can only follow the SELECT.
## Supported variables
* `SQL_AUTO_IS_NULL`

12
docs/zh-CN/administrator-guide/variables.md
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@ -85,6 +85,18 @@ SET exec_mem_limit = 10 * 1024 * 1024 * 1024;
SET forward_to_master = concat('tr', 'u', 'e');
```
### 在查询语句中设置变量
在一些场景中，我们可能需要对某些查询有针对性的设置变量。
通过使用SET_VAR提示可以在查询中设置会话变量（在单个语句内生效）。例子：
```
SELECT /*+ SET_VAR(exec_mem_limit = 8589934592) */ name FROM people ORDER BY name;
SELECT /*+ SET_VAR(query_timeout = 1) */ sleep(3);
```
注意注释必须以/*+ 开头，并且只能跟随在SELECT之后。
## 支持的变量
* `SQL_AUTO_IS_NULL`

26
fe/fe-core/src/main/cup/sql_parser.cup
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@ -20,6 +20,7 @@ package org.apache.doris.analysis;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@ -255,7 +256,7 @@ terminal String KW_ADD, KW_ADMIN, KW_AFTER, KW_AGGREGATE, KW_ALL, KW_ALTER, KW_A
KW_RANDOM, KW_RANGE, KW_READ, KW_RECOVER, KW_REGEXP, KW_RELEASE, KW_RENAME,
KW_REPAIR, KW_REPEATABLE, KW_REPOSITORY, KW_REPOSITORIES, KW_REPLACE, KW_REPLACE_IF_NOT_NULL, KW_REPLICA, KW_RESOURCE, KW_RESOURCES, KW_RESTORE, KW_RETURNS, KW_RESUME, KW_REVOKE,
KW_RIGHT, KW_ROLE, KW_ROLES, KW_ROLLBACK, KW_ROLLUP, KW_ROUTINE, KW_ROW, KW_ROWS,
KW_SCHEMA, KW_SCHEMAS, KW_SECOND, KW_SELECT, KW_SEMI, KW_SERIALIZABLE, KW_SESSION, KW_SET, KW_SETS, KW_SHOW, KW_SIGNED,
KW_SCHEMA, KW_SCHEMAS, KW_SECOND, KW_SELECT, KW_SEMI, KW_SERIALIZABLE, KW_SESSION, KW_SET, KW_SETS, KW_SET_VAR, KW_SHOW, KW_SIGNED,
KW_SMALLINT, KW_SNAPSHOT, KW_SONAME, KW_SPLIT, KW_START, KW_STATUS, KW_STOP, KW_STORAGE, KW_STRING,
KW_SUM, KW_SUPERUSER, KW_SYNC, KW_SYSTEM,
KW_TABLE, KW_TABLES, KW_TABLET, KW_TASK, KW_TEMPORARY, KW_TERMINATED, KW_THAN, KW_TIME, KW_THEN, KW_TIMESTAMP, KW_TINYINT,
@ -380,6 +381,7 @@ nonterminal InlineViewRef inline_view_ref;
nonterminal JoinOperator join_operator;
nonterminal ArrayList<String> opt_plan_hints;
nonterminal ArrayList<String> opt_sort_hints;
nonterminal HashMap<String, String> opt_select_hints;
nonterminal Expr sign_chain_expr;
nonterminal Qualifier opt_set_qualifier;
nonterminal Operation set_op;
@ -3298,21 +3300,37 @@ expr_or_default ::=
;
select_clause ::=
KW_SELECT select_list:l
KW_SELECT opt_select_hints:hints select_list:l
{:
l.setOptHints(hints);
RESULT = l;
:}
| KW_SELECT KW_ALL select_list:l
| KW_SELECT opt_select_hints:hints KW_ALL select_list:l
{:
l.setOptHints(hints);
RESULT = l;
:}
| KW_SELECT KW_DISTINCT select_list:l
| KW_SELECT opt_select_hints:hints KW_DISTINCT select_list:l
{:
l.setOptHints(hints);
l.setIsDistinct(true);
RESULT = l;
:}
;
opt_select_hints ::=
COMMENTED_PLAN_HINT_START KW_SET_VAR LPAREN ident_or_text:k EQUAL literal:v RPAREN COMMENTED_PLAN_HINT_END
{:
HashMap<String, String> map = new HashMap<String, String>();
map.put(k, v.getStringValue());
RESULT = map;
:}
| /* empty */
{:
RESULT = null;
:}
;
select_list ::=
select_sublist:list
{:

12
fe/fe-core/src/main/java/org/apache/doris/analysis/SelectList.java
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@ -24,12 +24,14 @@ import com.google.common.base.Predicates;
import com.google.common.collect.Lists;
import java.util.List;
import java.util.Map;
/**
* Select list items plus distinct clause.
*/
public class SelectList {
private boolean isDistinct;
private Map<String, String> optHints;
// ///////////////////////////////////////
// BEGIN: Members that need to be reset()
@ -72,7 +74,15 @@ public class SelectList {
public void setIsDistinct(boolean value) {
isDistinct = value;
}
public Map<String, String> getOptHints() {
return optHints;
}
public void setOptHints(Map<String, String> optHints) {
this.optHints = optHints;
}
public void reset() {
for (SelectListItem item : items) {
if (!item.isStar()) {

15
fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java
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@ -36,6 +36,8 @@ import org.apache.doris.analysis.StatementBase;
import org.apache.doris.analysis.StmtRewriter;
import org.apache.doris.analysis.UnsupportedStmt;
import org.apache.doris.analysis.UseStmt;
import org.apache.doris.analysis.SetVar;
import org.apache.doris.analysis.StringLiteral;
import org.apache.doris.catalog.Catalog;
import org.apache.doris.catalog.Column;
import org.apache.doris.catalog.Database;
@ -238,8 +240,19 @@ public class StmtExecutor {
context.setQueryId(new TUniqueId(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits()));
try {
// support select hint e.g. select /*+ SET_VAR(query_timeout=1) */ sleep(3);
SessionVariable sessionVariable = context.getSessionVariable();
if (parsedStmt != null && parsedStmt instanceof SelectStmt) {
SelectStmt selectStmt = (SelectStmt) parsedStmt;
Map<String, String> optHints = selectStmt.getSelectList().getOptHints();
if(optHints != null) {
for (String key : optHints.keySet()) {
VariableMgr.setVar(sessionVariable, new SetVar(key, new StringLiteral(optHints.get(key))));
}
}
}
// analyze this query
analyze(context.getSessionVariable().toThrift());
analyze(sessionVariable.toThrift());
if (isForwardToMaster()) {
forwardToMaster();

1
fe/fe-core/src/main/jflex/sql_scanner.flex
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@ -327,6 +327,7 @@ import org.apache.doris.qe.SqlModeHelper;
keywordMap.put("serializable", new Integer(SqlParserSymbols.KW_SERIALIZABLE));
keywordMap.put("session", new Integer(SqlParserSymbols.KW_SESSION));
keywordMap.put("set", new Integer(SqlParserSymbols.KW_SET));
keywordMap.put("set_var", new Integer(SqlParserSymbols.KW_SET_VAR));
keywordMap.put("sets", new Integer(SqlParserSymbols.KW_SETS));
keywordMap.put("show", new Integer(SqlParserSymbols.KW_SHOW));
keywordMap.put("signed", new Integer(SqlParserSymbols.KW_SIGNED));

24
fe/fe-core/src/test/java/org/apache/doris/analysis/SelectStmtTest.java Executable file → Normal file
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@ -19,6 +19,8 @@ package org.apache.doris.analysis;
import org.apache.doris.common.AnalysisException;
import org.apache.doris.qe.ConnectContext;
import org.apache.doris.planner.Planner;
import org.apache.doris.qe.VariableMgr;
import org.apache.doris.utframe.DorisAssert;
import org.apache.doris.utframe.UtFrameUtils;
@ -453,4 +455,26 @@ public class SelectStmtTest {
String sql4 = " SELECT * FROM table1 table2";
Assert.assertTrue(dorisAssert.query(sql4).explainQuery().contains("`table2`.`__DORIS_DELETE_SIGN__` = 0"));
}
@Test
public void testSelectHintSetVar() throws Exception {
String sql = "SELECT sleep(3);";
Planner planner = dorisAssert.query(sql).internalExecuteOneAndGetPlan();
Assert.assertEquals(VariableMgr.getDefaultSessionVariable().getQueryTimeoutS(),
planner.getPlannerContext().getQueryOptions().query_timeout);
sql = "SELECT /*+ SET_VAR(query_timeout = 1) */ sleep(3);";
planner = dorisAssert.query(sql).internalExecuteOneAndGetPlan();
Assert.assertEquals(1, planner.getPlannerContext().getQueryOptions().query_timeout);
sql = "select * from db1.partition_table where datekey=20200726";
planner = dorisAssert.query(sql).internalExecuteOneAndGetPlan();
Assert.assertEquals(VariableMgr.getDefaultSessionVariable().getMaxExecMemByte(),
planner.getPlannerContext().getQueryOptions().mem_limit);
sql = "select /*+ SET_VAR(exec_mem_limit = 8589934592) */ poi_id, count(*) from db1.partition_table " +
"where datekey=20200726 group by 1";
planner = dorisAssert.query(sql).internalExecuteOneAndGetPlan();
Assert.assertEquals(8589934592L, planner.getPlannerContext().getQueryOptions().mem_limit);
}
}

16
fe/fe-core/src/test/java/org/apache/doris/utframe/DorisAssert.java
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@ -23,10 +23,14 @@ import org.apache.doris.analysis.CreateDbStmt;
import org.apache.doris.analysis.CreateMaterializedViewStmt;
import org.apache.doris.analysis.CreateTableStmt;
import org.apache.doris.analysis.DropTableStmt;
import org.apache.doris.analysis.SqlParser;
import org.apache.doris.analysis.SqlScanner;
import org.apache.doris.analysis.StatementBase;
import org.apache.doris.catalog.Catalog;
import org.apache.doris.cluster.ClusterNamespace;
import org.apache.doris.common.AnalysisException;
import org.apache.doris.common.Config;
import org.apache.doris.common.util.SqlParserUtils;
import org.apache.doris.planner.Planner;
import org.apache.doris.qe.ConnectContext;
import org.apache.doris.qe.QueryState;
@ -38,6 +42,8 @@ import org.apache.commons.lang.StringUtils;
import org.junit.Assert;
import java.io.IOException;
import java.io.StringReader;
import java.util.List;
import java.util.Map;
import java.util.stream.Stream;
@ -162,5 +168,15 @@ public class DorisAssert {
System.out.println(explainString);
return explainString;
}
public Planner internalExecuteOneAndGetPlan() throws Exception{
SqlScanner input = new SqlScanner(new StringReader(sql), ctx.getSessionVariable().getSqlMode());
SqlParser parser = new SqlParser(input);
List<StatementBase> stmts = SqlParserUtils.getMultiStmts(parser);
StmtExecutor stmtExecutor = new StmtExecutor(connectContext, stmts.get(0));
stmtExecutor.execute();
return stmtExecutor.planner();
}
}
}