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提交 f4591330 authored 作者: Evgenij Ryazanov's avatar Evgenij Ryazanov
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Add support of PERCENT in FETCH and TOP clauses

上级 a00b17bd
隐藏空白字符变更
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正在显示 包含 159 行增加 和 15 行删除
h2/src/docsrc/help/help.csv
浏览文件 @ f4591330
......@@ -3,7 +3,7 @@
# Initial Developer: H2 Group
"SECTION","TOPIC","SYNTAX","TEXT","EXAMPLE"
"Commands (DML)","SELECT","
SELECT [ TOP term [ WITH TIES ] ]
SELECT [ TOP term [ PERCENT ] [ WITH TIES ] ]
[ DISTINCT [ ON ( expression [,...] ) ] | ALL ]
selectExpression [,...]
FROM tableExpression [,...] [ WHERE expression ]
......@@ -12,7 +12,7 @@ FROM tableExpression [,...] [ WHERE expression ]
[ ORDER BY order [,...] ]
[ { LIMIT expression [ OFFSET expression ] [ SAMPLE_SIZE rowCountInt ] }
| { [ OFFSET expression { ROW | ROWS } ]
[ FETCH { FIRST | NEXT } expression { ROW | ROWS }
[ FETCH { FIRST | NEXT } [ [ expression ] PERCENT ] { ROW | ROWS }
{ ONLY | WITH TIES } ] } ]
[ FOR UPDATE ]
","
......@@ -22,7 +22,7 @@ HAVING filter rows after grouping.
ORDER BY sorts the result by the given column(s) or expression(s).
UNION combines the result of this query with the results of another query.
LIMIT and FETCH FIRST/NEXT ROW(S) ONLY limits the number of rows returned by the query (no limit if null or smaller than zero).
FETCH FIRST/NEXT, LIMIT or TOP limits the number of rows returned by the query (no limit if null or smaller than zero).
OFFSET specified how many rows to skip.
Please note using high offset values should be avoided because it can cause performance problems.
SAMPLE_SIZE limits the number of rows read for aggregate queries.
......
h2/src/main/org/h2/command/Parser.java
浏览文件 @ f4591330
......@@ -2372,11 +2372,14 @@ public class Parser {
if (!readIf("FIRST")) {
read("NEXT");
}
if (readIf("ROW")) {
if (readIf("ROW") || readIf("ROWS")) {
command.setLimit(ValueExpression.get(ValueInt.get(1)));
} else {
Expression limit = readExpression().optimize(session);
command.setLimit(limit);
if (readIf("PERCENT")) {
command.setFetchPercent(true);
}
if (!readIf("ROW")) {
read("ROWS");
}
......@@ -2532,6 +2535,9 @@ public class Parser {
// SELECT TOP 1 (+?) AS A FROM TEST
Expression limit = readTerm().optimize(session);
command.setLimit(limit);
if (readIf("PERCENT")) {
command.setFetchPercent(true);
}
if (readIf(WITH)) {
read("TIES");
command.setWithTies(true);
......
h2/src/main/org/h2/command/dml/Query.java
浏览文件 @ f4591330
......@@ -48,6 +48,11 @@ public abstract class Query extends Prepared {
*/
protected Expression limitExpr;
/**
* Whether limit expression specifies percentage of rows.
*/
protected boolean fetchPercent;
/**
* Whether tied rows should be included in result too.
*/
......@@ -650,8 +655,16 @@ public abstract class Query extends Prepared {
return limitExpr;
}
public void setFetchPercent(boolean fetchPercent) {
this.fetchPercent = fetchPercent;
}
public boolean isFetchPercent() {
return fetchPercent;
}
public void setWithTies(boolean withTies) {
this.withTies = true;
this.withTies = withTies;
}
public boolean isWithTies() {
......@@ -699,12 +712,18 @@ public abstract class Query extends Prepared {
void appendLimitToSQL(StringBuilder buff) {
if (limitExpr != null) {
if (withTies) {
if (fetchPercent || withTies) {
if (offsetExpr != null) {
buff.append("\nOFFSET ").append(StringUtils.unEnclose(offsetExpr.getSQL())).append(" ROWS");
}
buff.append("\nFETCH NEXT ").append(StringUtils.unEnclose(limitExpr.getSQL()))
.append(" ROWS WITH TIES");
buff.append("\nFETCH NEXT ").append(StringUtils.unEnclose(limitExpr.getSQL()));
if (fetchPercent) {
buff.append(" PERCENT");
}
buff.append(" ROWS");
if (withTies) {
buff.append(" WITH TIES");
}
} else {
buff.append("\nLIMIT ").append(StringUtils.unEnclose(limitExpr.getSQL()));
if (offsetExpr != null) {
......
h2/src/main/org/h2/command/dml/Select.java
浏览文件 @ f4591330
......@@ -724,6 +724,17 @@ public class Select extends Query {
limitRows = Math.min(l, limitRows);
}
}
boolean fetchPercent = this.fetchPercent;
if (fetchPercent) {
// Need to check it row, because negative limit has special treatment later
if (limitRows < 0 || limitRows > 100) {
throw DbException.getInvalidValueException("FETCH PERCENT", limitRows);
}
// 0 PERCENT means 0
if (limitRows == 0) {
fetchPercent = false;
}
}
long offset;
if (offsetExpr != null) {
offset = offsetExpr.getValue(session).getLong();
......@@ -735,7 +746,7 @@ public class Select extends Query {
}
boolean lazy = session.isLazyQueryExecution() &&
target == null && !isForUpdate && !isQuickAggregateQuery &&
limitRows != 0 && !withTies && offset == 0 && isReadOnly();
limitRows != 0 && !fetchPercent && !withTies && offset == 0 && isReadOnly();
int columnCount = expressions.size();
LocalResult result = null;
if (!lazy && (target == null ||
......@@ -743,7 +754,7 @@ public class Select extends Query {
result = createLocalResult(result);
}
// Do not add rows before OFFSET to result if possible
boolean quickOffset = true;
boolean quickOffset = !fetchPercent;
if (sort != null && (!sortUsingIndex || isAnyDistinct() || withTies)) {
result = createLocalResult(result);
result.setSortOrder(sort);
......@@ -791,6 +802,8 @@ public class Select extends Query {
lazy &= to == null;
LazyResult lazyResult = null;
if (limitRows != 0) {
// Cannot apply limit now if percent is specified
int limit = fetchPercent ? -1 : limitRows;
try {
if (isQuickAggregateQuery) {
queryQuick(columnCount, to, quickOffset && offset > 0);
......@@ -801,9 +814,9 @@ public class Select extends Query {
queryGroup(columnCount, result, offset, quickOffset);
}
} else if (isDistinctQuery) {
queryDistinct(to, offset, limitRows, withTies, quickOffset);
queryDistinct(to, offset, limit, withTies, quickOffset);
} else {
lazyResult = queryFlat(columnCount, to, offset, limitRows, withTies, quickOffset);
lazyResult = queryFlat(columnCount, to, offset, limit, withTies, quickOffset);
}
if (quickOffset) {
offset = 0;
......@@ -833,6 +846,7 @@ public class Select extends Query {
}
if (limitRows >= 0) {
result.setLimit(limitRows);
result.setFetchPercent(fetchPercent);
result.setWithTies(withTies);
}
if (result != null) {
......
h2/src/main/org/h2/command/dml/SelectUnion.java
浏览文件 @ f4591330
......@@ -193,7 +193,7 @@ public class SelectUnion extends Query {
int columnCount = left.getColumnCount();
if (session.isLazyQueryExecution() && unionType == UnionType.UNION_ALL && !distinct &&
sort == null && !randomAccessResult && !isForUpdate &&
offsetExpr == null && isReadOnly()) {
offsetExpr == null && !fetchPercent && !withTies && isReadOnly()) {
int limit = -1;
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
......@@ -284,6 +284,7 @@ public class SelectUnion extends Query {
Value v = limitExpr.getValue(session);
if (v != ValueNull.INSTANCE) {
result.setLimit(v.getInt());
result.setFetchPercent(fetchPercent);
result.setWithTies(withTies);
}
}
......
h2/src/main/org/h2/result/LocalResult.java
浏览文件 @ f4591330
......@@ -41,6 +41,7 @@ public class LocalResult implements ResultInterface, ResultTarget {
private Value[] currentRow;
private int offset;
private int limit = -1;
private boolean fetchPercent;
private boolean withTies;
private boolean limitsWereApplied;
private ResultExternal external;
......@@ -387,9 +388,16 @@ public class LocalResult implements ResultInterface, ResultTarget {
}
int offset = Math.max(this.offset, 0);
int limit = this.limit;
if (offset == 0 && limit < 0 || rowCount == 0) {
if (offset == 0 && limit < 0 && !fetchPercent || rowCount == 0) {
return;
}
if (fetchPercent) {
if (limit < 0 || limit > 100) {
throw DbException.getInvalidValueException("FETCH PERCENT", limit);
}
// Oracle rounds percent up, do the same for now
limit = (limit * rowCount + 99) / 100;
}
boolean clearAll = offset >= rowCount || limit == 0;
if (!clearAll) {
int remaining = rowCount - offset;
......@@ -484,6 +492,13 @@ public class LocalResult implements ResultInterface, ResultTarget {
this.limit = limit;
}
/**
* @param fetchPercent whether limit expression specifies percentage of rows
*/
public void setFetchPercent(boolean fetchPercent) {
this.fetchPercent = fetchPercent;
}
/**
* @param withTies whether tied rows should be included in result too
*/
......
h2/src/test/org/h2/test/scripts/dml/select.sql
浏览文件 @ f4591330
......@@ -56,7 +56,7 @@ SELECT * FROM TEST ORDER BY A, B FETCH FIRST 4 ROWS WITH TIES;
> 1 2 3
> rows: 6
SELECT * FROM TEST ORDER BY A FETCH FIRST 1 ROW WITH TIES;
SELECT * FROM TEST ORDER BY A FETCH FIRST ROW WITH TIES;
> A B C
> - - -
> 1 1 1
......@@ -78,6 +78,31 @@ SELECT TOP (1) WITH TIES * FROM TEST ORDER BY A;
> 1 2 3
> rows: 6
SELECT TOP 1 PERCENT WITH TIES * FROM TEST ORDER BY A;
> A B C
> - - -
> 1 1 1
> 1 1 2
> 1 1 3
> 1 2 1
> 1 2 2
> 1 2 3
> rows: 6
SELECT TOP 51 PERCENT WITH TIES * FROM TEST ORDER BY A, B;
> A B C
> - - -
> 1 1 1
> 1 1 2
> 1 1 3
> 1 2 1
> 1 2 2
> 1 2 3
> 2 1 1
> 2 1 2
> 2 1 3
> rows: 9
SELECT * FROM TEST ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 1 ROW WITH TIES;
> A B C
> - - -
......@@ -86,6 +111,43 @@ SELECT * FROM TEST ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 1 ROW WITH TIES;
> 1 2 3
> rows: 3
SELECT * FROM TEST FETCH NEXT ROWS ONLY;
> A B C
> - - -
> 1 1 1
> rows: 1
SELECT * FROM TEST FETCH FIRST 101 PERCENT ROWS ONLY;
> exception INVALID_VALUE_2
SELECT * FROM TEST FETCH FIRST -1 PERCENT ROWS ONLY;
> exception INVALID_VALUE_2
SELECT * FROM TEST FETCH FIRST 0 PERCENT ROWS ONLY;
> A B C
> - - -
> rows: 0
SELECT * FROM TEST FETCH FIRST 1 PERCENT ROWS ONLY;
> A B C
> - - -
> 1 1 1
> rows: 1
SELECT * FROM TEST FETCH FIRST 10 PERCENT ROWS ONLY;
> A B C
> - - -
> 1 1 1
> 1 1 2
> rows: 2
SELECT * FROM TEST OFFSET 2 ROWS FETCH NEXT 10 PERCENT ROWS ONLY;
> A B C
> - - -
> 1 1 3
> 1 2 1
> rows: 2
CREATE INDEX TEST_A_IDX ON TEST(A);
> ok
......@@ -123,12 +185,39 @@ SELECT * FROM TEST FETCH FIRST 1 ROW WITH TIES;
> 1 2 4
> rows: 4
(SELECT * FROM TEST) UNION (SELECT 1, 2, 4) ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 50 PERCENT ROWS ONLY;
> A B C
> - - -
> 1 2 1
> 1 2 2
> 1 2 3
> 1 2 4
> 2 1 1
> 2 1 2
> 2 1 3
> rows: 7
(SELECT * FROM TEST) UNION (SELECT 1, 2, 4) ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 40 PERCENT ROWS WITH TIES;
> A B C
> - - -
> 1 2 1
> 1 2 2
> 1 2 3
> 1 2 4
> 2 1 1
> 2 1 2
> 2 1 3
> rows: 7
(SELECT * FROM TEST) UNION (SELECT 1, 2, 4) FETCH NEXT 1 ROW WITH TIES;
> exception WITH_TIES_WITHOUT_ORDER_BY
EXPLAIN SELECT * FROM TEST ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 1 ROW WITH TIES;
>> SELECT TEST.A, TEST.B, TEST.C FROM PUBLIC.TEST /* PUBLIC.TEST_A_B_IDX */ ORDER BY 1, 2 OFFSET 3 ROWS FETCH NEXT 1 ROWS WITH TIES /* index sorted */
EXPLAIN SELECT * FROM TEST ORDER BY A, B OFFSET 3 ROWS FETCH NEXT 1 PERCENT ROWS WITH TIES;
>> SELECT TEST.A, TEST.B, TEST.C FROM PUBLIC.TEST /* PUBLIC.TEST_A_B_IDX */ ORDER BY 1, 2 OFFSET 3 ROWS FETCH NEXT 1 PERCENT ROWS WITH TIES /* index sorted */
DROP TABLE TEST;
> ok
......
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