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doebele pushed a commit to branch master
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The following commit(s) were added to refs/heads/master by this push:
new e0ca4c42 EMPIREDB-456 DBUtils: improved initial array capacity for
list queries
e0ca4c42 is described below
commit e0ca4c42974ed23daba59493200266e63efb492c
Author: Rainer Döbele <[email protected]>
AuthorDate: Thu Apr 24 12:38:59 2025 +0200
EMPIREDB-456
DBUtils: improved initial array capacity for list queries
---
.../main/java/org/apache/empire/db/DBUtils.java | 70 ++++++++++++----------
1 file changed, 37 insertions(+), 33 deletions(-)
diff --git a/empire-db/src/main/java/org/apache/empire/db/DBUtils.java
b/empire-db/src/main/java/org/apache/empire/db/DBUtils.java
index 49e66a7f..950b6648 100644
--- a/empire-db/src/main/java/org/apache/empire/db/DBUtils.java
+++ b/empire-db/src/main/java/org/apache/empire/db/DBUtils.java
@@ -69,9 +69,9 @@ public class DBUtils implements DBContextAware
// Threshold for long running queries in milliseconds
protected long longRunndingStmtThreshold = 30000;
// Default list capacity
- protected int DEFAULT_LIST_CAPACITY = 10;
+ protected int DEFAULT_LIST_CAPACITY = 10; // Max-capacity before using
ArrayList.DEFAULT_CAPACITY
// Max-Rows for list queries
- protected int MAX_QUERY_ROWS = 999;
+ protected int MAX_QUERY_ROWS = 999;
// Log max String length
protected int LOG_MAX_STRING_LENGTH = 40;
// Log New-Line
@@ -795,7 +795,18 @@ public class DBUtils implements DBContextAware
{
return querySingleRow(cmd.getSelect(), cmd.getParamValues());
}
-
+
+ /**
+ * Returns the initial array list capacity.
+ * Usually returns 0 in order to use the ArrayList default.
+ * @param pageSize the designated page size
+ * @return the initial array list capacity or 0 to use the default
+ */
+ protected int getInitialListCapacity(int pageSize)
+ {
+ // return 0 in order to use ArrayList.DEFAULT_CAPACITY on first insert
+ return (pageSize>0 && pageSize<DEFAULT_LIST_CAPACITY) ? pageSize : 0;
+ }
/**
* Called to inform that the limit for DataList, Record and Bean queries
has exceeded the maximum value
@@ -846,7 +857,7 @@ public class DBUtils implements DBContextAware
* @param cmd the command
* @param factory the Factory to be used for each list item
* @param first the number of records to skip from the beginning of the
result
- * @param pageSize the maximum number of items to add to the list or -1
(default) for all
+ * @param pageSize the maximum number of items to add to the list or -1
(default) for a maximum of MAX_QUERY_ROWS
* @return the list
*/
public <T extends DataListEntry> List<T> queryDataList(DBCommandExpr cmd,
DataListFactory<T> factory, int first, int pageSize)
@@ -858,12 +869,12 @@ public class DBUtils implements DBContextAware
factory.prepareQuery(cmd, context);
// check pageSize
if (pageSize==0)
- { log.warn("PageSize must not be 0. Setting to -1 for all
records!");
+ { log.warn("PageSize should not be 0. Setting to -1 for a
maximum of MAX_QUERY_ROWS records!");
pageSize = -1;
}
// set range
DBMSHandler dbms = context.getDbms();
- if (pageSize>0 && dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
+ if (pageSize>0 && pageSize<Integer.MAX_VALUE &&
dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
{ // let the database limit the rows
if (first>0 && dbms.isSupported(DBMSFeature.QUERY_SKIP_ROWS))
{ // let the database skip the rows
@@ -880,24 +891,22 @@ public class DBUtils implements DBContextAware
r.skipRows(first);
}
// Create a list of data entries
- int maxCount = (pageSize>=0) ? pageSize : MAX_QUERY_ROWS;
- list = factory.newList((pageSize>=0) ? pageSize : 10);
+ int maxCount = (pageSize>0) ? pageSize : MAX_QUERY_ROWS;
+ list = factory.newList(getInitialListCapacity(pageSize));
// add data
int rownum = 0;
- while (r.moveNext() && maxCount != 0)
+ while (r.moveNext() && rownum<maxCount)
{ // Create bean an init
T entry = factory.newEntry(rownum, r);
if (entry==null)
continue;
// add entry
list.add(entry);
+ // next
rownum++;
- // Decrease count
- if (maxCount > 0)
- maxCount--;
}
// check
- if (rownum==MAX_QUERY_ROWS)
+ if (rownum==maxCount && rownum==MAX_QUERY_ROWS)
queryRowLimitExeeded();
// done
return list;
@@ -1043,7 +1052,7 @@ public class DBUtils implements DBContextAware
* @param cmd the command
* @param factory the factory for creating record objects
* @param first the number of records to skip from the beginning of the
result
- * @param pageSize the maximum number of items to add to the list or -1
(default) for all
+ * @param pageSize the maximum number of items to add to the list or -1
(default) for a maximum of MAX_QUERY_ROWS
* @return the list
*/
public <R extends DBRecordBase> List<R> queryRecordList(DBCommand cmd,
DBRecordListFactory<R> factory, int first, int pageSize)
@@ -1055,12 +1064,12 @@ public class DBUtils implements DBContextAware
factory.prepareQuery(cmd, context);
// check pageSize
if (pageSize==0)
- { log.warn("PageSize must not be 0. Setting to -1 for all
records!");
+ { log.warn("PageSize should not be 0. Setting to -1 for a
maximum of MAX_QUERY_ROWS records!");
pageSize = -1;
}
// set range
DBMSHandler dbms = context.getDbms();
- if (pageSize>0 && dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
+ if (pageSize>0 && pageSize<Integer.MAX_VALUE &&
dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
{ // let the database limit the rows
if (first>0 && dbms.isSupported(DBMSFeature.QUERY_SKIP_ROWS))
{ // let the database skip the rows
@@ -1077,24 +1086,22 @@ public class DBUtils implements DBContextAware
r.skipRows(first);
}
// Create a list of data entries
- int maxCount = (pageSize>=0) ? pageSize : MAX_QUERY_ROWS;
- list = factory.newList((pageSize>=0) ? pageSize :
DEFAULT_LIST_CAPACITY);
+ int maxCount = (pageSize>0) ? pageSize : MAX_QUERY_ROWS;
+ list = factory.newList(getInitialListCapacity(pageSize));
// add data
int rownum = 0;
- while (r.moveNext() && maxCount != 0)
+ while (r.moveNext() && rownum<maxCount)
{ // Create bean an init
R entry = factory.newRecord(rownum, r);
if (entry==null)
continue;
// add entry
list.add(entry);
+ // next
rownum++;
- // Decrease count
- if (maxCount > 0)
- maxCount--;
}
// check
- if (rownum==MAX_QUERY_ROWS)
+ if (rownum==maxCount && rownum==MAX_QUERY_ROWS)
queryRowLimitExeeded();
// done
return list;
@@ -1193,7 +1200,7 @@ public class DBUtils implements DBContextAware
* @param factory the bean factory
* @param parent the parent object for the created beans (optional)
* @param first the first row
- * @param pageSize the maximum number of items to add to the list or -1
(default) for all
+ * @param pageSize the maximum number of items to add to the list or -1
(default) for a maximum of MAX_QUERY_ROWS
* @return the bean list
*/
public <T> List<T> queryBeanList(DBCommandExpr cmd, DBBeanListFactory<T>
factory, Object parent, int first, int pageSize)
@@ -1205,12 +1212,12 @@ public class DBUtils implements DBContextAware
factory.prepareQuery(cmd, context);
// check pageSize
if (pageSize==0)
- { log.warn("PageSize must not be 0. Setting to -1 for all
records!");
+ { log.warn("PageSize should not be 0. Setting to -1 for a
maximum of MAX_QUERY_ROWS records!");
pageSize = -1;
}
// set range
DBMSHandler dbms = context.getDbms();
- if (pageSize>0 && dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
+ if (pageSize>0 && pageSize<Integer.MAX_VALUE &&
dbms.isSupported(DBMSFeature.QUERY_LIMIT_ROWS))
{ // let the database limit the rows
if (first>0 && dbms.isSupported(DBMSFeature.QUERY_SKIP_ROWS))
{ // let the database skip the rows
@@ -1227,11 +1234,11 @@ public class DBUtils implements DBContextAware
r.skipRows(first);
}
// Create a list of data entries
- int maxCount = (pageSize>=0) ? pageSize : MAX_QUERY_ROWS;
- list = factory.newList((pageSize>=0) ? pageSize :
DEFAULT_LIST_CAPACITY);
+ int maxCount = (pageSize>0) ? pageSize : MAX_QUERY_ROWS;
+ list = factory.newList(getInitialListCapacity(pageSize));
// add data
int rownum = 0;
- while (r.moveNext() && maxCount != 0)
+ while (r.moveNext() && rownum<maxCount)
{ // Create bean an init
T item = factory.newItem(rownum, r);
if (item==null)
@@ -1243,12 +1250,9 @@ public class DBUtils implements DBContextAware
((DataBean<?>)item).initialize(((DBObject)r).getDatabase(), context, rownum,
parent);
// next
rownum++;
- // Decrease count
- if (maxCount > 0)
- maxCount--;
}
// check
- if (rownum==MAX_QUERY_ROWS)
+ if (rownum==maxCount && rownum==MAX_QUERY_ROWS)
queryRowLimitExeeded();
// done
return list;
