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OPENJPA-2111: Optimize lookup when possible 

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@1232650 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Pinaki Poddar 2012-01-17 23:37:39 +00:00
parent 3c1a262106
commit 6430d8eb92
1 changed files with 84 additions and 17 deletions
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101
openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SelectImpl.java
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@ -2330,8 +2330,7 @@ public class SelectImpl
extends ResultSetResult
implements PathJoins {
private SelectImpl _sel = null;
private Map<Column, Object> _cachedColumnAlias = null;
private SelectImpl _sel;
// position in selected columns list where we expect the next load
private int _pos = 0;
@ -2414,14 +2413,12 @@ public class SelectImpl
protected boolean containsInternal(Object obj, Joins joins) {
// we key directly on objs and join-less cols, or on the alias
// for cols with joins
if (_sel._selects.isOptimizable()) {
return obj instanceof Column && _sel._selects.getObjectIndex((Column)obj) != null;
}
PathJoins pj = getJoins(joins);
if (pj != null && pj.path() != null) {
Object columnAlias = getColumnAlias((Column) obj, pj);
if (joins == null) {
if (_cachedColumnAlias == null)
_cachedColumnAlias = new HashMap<Column, Object>();
_cachedColumnAlias.put((Column) obj, columnAlias);
}
return columnAlias != null && _sel._selects.contains(columnAlias);
}
return obj != null && _sel._selects.contains(obj);
@ -2460,8 +2457,16 @@ public class SelectImpl
return super.nextInternal();
}
/**
* Finds index of the given object with optional join information.
* The index refers to the position of the value in the JDBC result set.
*/
protected int findObject(Object obj, Joins joins)
throws SQLException {
if (_sel._selects.isOptimizable()) {
return _sel._selects.getObjectIndex((Column)obj);
}
if (_pos == _sel._selects.size())
_pos = 0;
@ -2472,21 +2477,16 @@ public class SelectImpl
if (pj != null && pj.path() != null) {
Column col = (Column) obj;
pk = (col.isPrimaryKey()) ? Boolean.TRUE : Boolean.FALSE;
if (joins == null && _cachedColumnAlias != null) {
obj = _cachedColumnAlias.get(col);
if (obj == null)
obj = getColumnAlias(col, pj);
} else {
obj = getColumnAlias(col, pj);
}
obj = getColumnAlias(col, pj);
if (obj == null)
throw new SQLException(col.getTable() + ": "
+ pj.path() + " (" + _sel._aliases + ")");
}
// we load in the same order we select, more or less...
if (_sel._selects.get(_pos).equals(obj))
if (_sel._selects.get(_pos).equals(obj)) {
return ++_pos;
}
// if we're looking for a primary key, try back a couple places,
// since pks might be selected in a slightly different order than
@ -2496,8 +2496,9 @@ public class SelectImpl
? Boolean.TRUE : Boolean.FALSE;
if (pk.booleanValue()) {
for (int i = _pos - 1; i >= 0 && i >= _pos - 3; i--)
if (_sel._selects.get(i).equals(obj))
if (_sel._selects.get(i).equals(obj)) {
return i + 1;
}
}
// search forward on the assumption that we might be skipping
@ -2515,8 +2516,9 @@ public class SelectImpl
// position marker at its current place cause subsequent loads will
// still probably start from there
for (int i = 0; i < _pos; i++)
if (_sel._selects.get(i).equals(obj))
if (_sel._selects.get(i).equals(obj)) {
return i + 1;
}
// somethings's wrong...
throw new SQLException(obj.toString());
@ -3087,6 +3089,7 @@ public class SelectImpl
protected Map<Object,String> _selectAs = null;
protected DBDictionary _dict = null;
/**
* Add all aliases from another instance.
*/
@ -3266,7 +3269,71 @@ public class SelectImpl
_selectAs = null;
_idents = null;
}
// Selected column lookup optimization.
private Boolean _optimizable;
Map<String,Integer> _indices = new HashMap<String, Integer>();
/**
* A set of selected terms become optimized for lookup if all the terms
* are columns (may be some with joins) but their names are distinct
* In such case, an index lookup is possible only by the name of the column
* without any need to recompute alias every time (i.e. for every term for
* every row) during lookup.
* <br>
* This routine computes once and only once per instance to determine
* whether such optimization is permissible.
* If {@link JDBCConfiguration#getSelectCacheEnabled()} select caching is in effect,
* then the same {@link Selects projection term} will be reused and such optimization
* may prove useful.
*/
boolean isOptimizable() {
if (_optimizable != null) {
return _optimizable.booleanValue();
}
_optimizable = true;
int N = size();
String columnName = null;
for (int i = 0; i < N; i++) {
Object key = get(i);
if (key instanceof Column) {
columnName = ((Column) key).getIdentifier().getName();
} else if (key instanceof String) {
int dot = ((String)key).lastIndexOf('.');
if (dot != -1) {
columnName = ((String)key).substring(dot+1);
}
} else {
columnName = null;
}
if (columnName != null && !_indices.containsKey(columnName)) {
_indices.put(columnName, i+1);
} else {
_indices.clear();
_optimizable = false;
break;
}
}
return _optimizable;
}
/**
* Gets index of the given column assuming that this instance is optimized.
* @return JDBC index of the given column
* @see #isOptimizable()
*/
Integer getObjectIndex(Column col) {
return _indices.get(col.getIdentifier().getName());
}
// for debugging
String toString(Object o) {
if (o == null) return "null";
return o.toString() + '[' + o.getClass().getSimpleName() + '@'
+ Integer.toHexString(System.identityHashCode(o)) + ']';
}
}
// ------------- end of SelectImpl$Selects -----------------------------------------
public Joins setCorrelatedVariable(String var) {
if (var == null)