# Optimizing connection failed

**URL:** <https://forum.cloverdx.com/t/optimizing-connection-failed/663>\
**Category:** CloverDX Platform\
**Created:** [February 11, 2010, 12:00am UTC](https://forum.cloverdx.com/t/optimizing-connection-failed/663 "2010-02-11T00:00:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![evergreen](https://avatars.discourse-cdn.com/v4/letter/e/6de8d8/32.png) [@evergreen](https://forum.cloverdx.com/u/evergreen)\
**Post date:** [February 11, 2010, 12:00am UTC](https://forum.cloverdx.com/t/optimizing-connection-failed/663/1 "2010-02-11T00:00:00Z")

</div>

Hi,

I have made a database connection to the graph from Link DB connection.  
When I run the graph I am faced with the following error.  
“ptimizing connection failed: READ\_COMMITTED and SERIALIZABLE are the only valid transaction levels”  
I have used the oracle’s ojdbc14.jar specific jar  
Kindly tell me the solution for the same  
Below is the log.The graph runs successfully.  
DEBUG [WatchDog] - all edges initialized successfully…  
DEBUG [WatchDog] - initializing nodes:  
DEBUG [WatchDog] - DATA\_WRITER0 …OK  
INFO [WatchDog] - Select \* from UP  
WARN [WatchDog] - Optimizing connection failed: READ\_COMMITTED and SERIALIZABLE are the only valid transaction levels  
WARN [WatchDog] - Try to use another jdbc specific  
DEBUG [WatchDog] - DB\_EXECUTE0 …OK  
INFO [WatchDog] - [Clover] phase: 0 initialized successfully.  
INFO [WatchDog] - Starting up all nodes in phase [0]  
DEBUG [WatchDog] - DATA\_WRITER0 … started  
DEBUG [WatchDog] - DB\_EXECUTE0 … started  
INFO [WatchDog] - Successfully started all nodes in phase!  
INFO [WatchDog] - ----------------------\*\* Final tracking Log for phase [0] \*\*---------------------  
INFO [WatchDog] - Time: 11/02/10 12:11:14  
INFO [WatchDog] - Node Status Port #Records #KB aRec/s aKB/s  
INFO [WatchDog] - ---------------------------------------------------------------------------------  
INFO [WatchDog] - DATA\_WRITER0 FINISHED\_OK  
INFO [WatchDog] - %cpu:… In:0 0 0 0 0  
INFO [WatchDog] - DB\_EXECUTE0 FINISHED\_OK  
INFO [WatchDog] - %cpu:… Out:0 0 0 0 0  
INFO [WatchDog] - ---------------------------------\*\* End of Log \*\*--------------------------------  
INFO [WatchDog] - Execution of phase [0] successfully finished - elapsed time(sec): 5  
INFO [WatchDog] - -----------------------\*\* Summary of Phases execution \*\*---------------------  
INFO [WatchDog] - Phase# Finished Status RunTime(sec) MemoryAllocation(KB)  
INFO [WatchDog] - 0 FINISHED\_OK 5 2498  
INFO [WatchDog] - ------------------------------\*\* End of Summary \*\*---------------------------  
INFO [WatchDog] - WatchDog thread finished - total execution time: 5 (sec)  
INFO [main] - Freeing graph resources.  
INFO [main] - Execution of graph successful !

The node code for the same is as below

```auto
[code]

<?xml version="1.0" encoding="UTF-8"?>
<Graph author="ashgfahdf" created="Tue Feb 02 10:46:14 IST 2010" guiVersion="2.8.2.RC1" id="1265107159356" licenseCode="javlinconsulting" licenseType="Commercial PRO" modified="Thu Feb 11 12:11:27 IST 2010" modifiedBy="ghshj" name="test" revision="1.30">
<Global>
<Metadata id="Metadata0" previewAttachmentCharset="ISO-8859-1">
<Record fieldDelimiter=";" name="UP_GROUP" previewAttachmentCharset="ISO-8859-1" recordDelimiter="\n" recordSize="-1" type="delimited">
<Field eofAsDelimiter="false" name="GROUP_ID" nullable="true" shift="0" size="0" type="string"/>
<Field eofAsDelimiter="false" name="CREATOR_ID" nullable="true" shift="0" size="0" type="string"/>
<Field eofAsDelimiter="false" name="ENTITY_TYPE_ID" nullable="true" shift="0" size="0" type="number"/>
<Field eofAsDelimiter="false" name="GROUP_NAME" nullable="true" shift="0" size="0" type="string"/>
<Field eofAsDelimiter="false" name="DESCRIPTION" nullable="true" shift="0" size="0" type="string"/>
</Record>
</Metadata>
<Connection dbConfig="${CONN_DIR}/SconnNew.cfg" id="Connection0" type="JDBC"/>
<Property fileURL="workspace.prm" id="GraphParameter0"/>
</Global>
<Phase number="0">
<Node enabled="enabled" fileURL="${DATAOUT_DIR}/testQuery.txt" guiHeight="0" guiName="UniversalDataWriter" guiWidth="0" guiX="376" guiY="169" id="DATA_WRITER0" type="DATA_WRITER"/>
<Node dbConnection="Connection0" enabled="enabled" guiHeight="0" guiName="DBExecute" guiWidth="0" guiX="141" guiY="169" id="DB_EXECUTE0" printStatements="true" sqlQuery="Select * from UP" type="DB_EXECUTE"/>
<Edge debugMode="true" fromNode="DB_EXECUTE0:0" guiBendpoints="" id="Edge1" inPort="Port 0 (in)" metadata="Metadata0" outPort="Port 0 (procedure output)" toNode="DATA_WRITER0:0"/>
</Phase>
</Graph>

[/code]

```

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<div class="post-metadata">

**Author:** ![avackova](https://avatars.discourse-cdn.com/v4/letter/a/65b543/32.png) [@avackova](https://forum.cloverdx.com/u/avackova)\
**Post date:** [February 11, 2010, 8:44am UTC](https://forum.cloverdx.com/t/optimizing-connection-failed/663/2 "2010-02-11T08:44:01Z")

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Hi,

these two messages mean, that DB doesn’t support READ\_UNCOMMITED transaction isolation level. Clover tries to set this level to achieve faster reading from the database.  
It’s not vital and graph execution goes on.  
I’ve created an issue ([http://bug.cloveretl.com/view.php?id=3750](http://bug.cloveretl.com/view.php?id=3750)) to not call thees settings for Oracle connection.

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<div class="post-metadata">

**Author:** ![evergreen](https://avatars.discourse-cdn.com/v4/letter/e/6de8d8/32.png) [@evergreen](https://forum.cloverdx.com/u/evergreen)\
**Post date:** [February 11, 2010, 8:46am UTC](https://forum.cloverdx.com/t/optimizing-connection-failed/663/3 "2010-02-11T08:46:00Z")

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Thank you very much avackova