Thanks for the reply Kathrine. So in theory however if Derby's estimate works correctly, the sorting should spill to disk and there should be no OOM errors, right?
I will get a copy of the database and setup to get the query plan. Thanks. Brett From: Katherine Marsden [mailto:[email protected]] Sent: Wednesday, February 15, 2012 12:10 PM To: [email protected] Subject: Re: Quetion on out memory usage On 2/15/2012 8:45 AM, Bergquist, Brett wrote: I had a user in our production server that performed a query through a web service interface that requested to retrieve and perform a multi-level sort on probably 30 million records. The tables being queried on are in a UNION (basically one table for each week of the year and the query was working across the this week and the previous week so it probably could not use the indexes to avoid the sort. Derby reported OutOfMemory errors. In derby.log are errors such as: Tue Feb 14 20:15:12 EST 2012 Thread[DRDAConnThread_68,5,main] (XID = 861337977), (SESSIONID = 45137761), (DATABASE = csemdb), (DRDAID = ????????.??-866660124046835337{112060}), Failed Statement is: SELECT r.MasterIp, BootCount, TestResultId, ProfileName, r.ProfileRefId, LatencyBucketsInUse, JitterBucketsInUse, UseOutOfSequence, StartDateTime, TestResultDescription, TestResultDescription2, PacketsSent, RoundTripPackets, OutOfOrderPackets, MinRoundTripLatency, MaxRoundTripLatency, TotalRoundTripLatency, LatencyBucketValue1, LatencyBucketValue2, LatencyBucketValue3, LatencyBucketValue4, LatencyBucketValue5, LatencyBucketValue6, LatencyBucketValue7, LatencyBucketValue8, LatencyBucketValue9, LatencyBucketValue10, JitterMeasurement, LocalRemoteJitterBucketValue1, LocalRemoteJitterBucketValue2, LocalRemoteJitterBucketValue3, LocalRemoteJitterBucketValue4, LocalRemoteJitterBucketValue5, LocalRemoteJitterBucketValue6, LocalRemoteJitterBucketValue7, LocalRemoteJitterBucketValue8, LocalRemoteJitterBucketValue9, MinLocalRemoteJitter, MaxLocalRemoteJitter, TotalLocalRemoteJitter, RemoteLocalJitterBucketValue1, RemoteLocalJitterBucketValue2, RemoteLocalJitterBucketValue3, RemoteLocalJitterBucketValue4, RemoteLocalJitterBucketValue5, RemoteLocalJitterBucketValue6, RemoteLocalJitterBucketValue7, RemoteLocalJitterBucketValue8, RemoteLocalJitterBucketValue9, MinRemoteLocalJitter, MaxRemoteLocalJitter, TotalRemoteLocalJitter, c1.Circuit as Circuit1, c2.Circuit as Circuit2 FROM PCS_V1.NPAResults r JOIN PCS_V1.NpaResultsProfile p on r.PROFILEREFID = p.PROFILEREFID JOIN PCS_V1.NPAResultsAddress a on r.ADDRESSREFID = a.ADDRESSREFID JOIN PCS_V1.NPAResultsCircuit c1 on r.CIRCUIT1REFID = c1.CIRCUITREFID JOIN PCS_V1.NPAResultsCircuit c2 on r.CIRCUIT2REFID = c2.CIRCUITREFID WHERE ReportKey >= '2012-02-03 12:45:00.0' AND ReportKey <= '2012-02-14 14:00:00.0' AND (r.ResultFlag = 0 OR (r.ResultFlag <> 0 AND r.RoundTripPackets > 0)) ORDER BY TestResultDescription, Circuit1, TestResultDescription2, ProfileName, StartDateTime java.lang.OutOfMemoryError: GC overhead limit exceeded I have not personally encountered the GC overhead limit, but google search indicates it is related to the amount of time spent on garbage collection ("too much") and can be overridden. http://www.petefreitag.com/item/746.cfm Tue Feb 14 23:48:28 EST 2012 Thread[DRDAConnThread_122,5,main] (XID = 861195891), (SESSIONID = 45103057), (DATABASE = csemdb), (DRDAID = ????????.??-448669783631952048{111972}), Failed Statement is: SELECT r.MasterIp, BootCount, TestResultId, ProfileName, r.ProfileRefId, LatencyBucketsInUse, JitterBucketsInUse, UseOutOfSequence, StartDateTime, TestResultDescription, TestResultDescription2, PacketsSent, RoundTripPackets, OutOfOrderPackets, MinRoundTripLatency, MaxRoundTripLatency, TotalRoundTripLatency, LatencyBucketValue1, LatencyBucketValue2, LatencyBucketValue3, LatencyBucketValue4, LatencyBucketValue5, LatencyBucketValue6, LatencyBucketValue7, LatencyBucketValue8, LatencyBucketValue9, LatencyBucketValue10, JitterMeasurement, LocalRemoteJitterBucketValue1, LocalRemoteJitterBucketValue2, LocalRemoteJitterBucketValue3, LocalRemoteJitterBucketValue4, LocalRemoteJitterBucketValue5, LocalRemoteJitterBucketValue6, LocalRemoteJitterBucketValue7, LocalRemoteJitterBucketValue8, LocalRemoteJitterBucketValue9, MinLocalRemoteJitter, MaxLocalRemoteJitter, TotalLocalRemoteJitter, RemoteLocalJitterBucketValue1, RemoteLocalJitterBucketValue2, RemoteLocalJitterBucketValue3, RemoteLocalJitterBucketValue4, RemoteLocalJitterBucketValue5, RemoteLocalJitterBucketValue6, RemoteLocalJitterBucketValue7, RemoteLocalJitterBucketValue8, RemoteLocalJitterBucketValue9, MinRemoteLocalJitter, MaxRemoteLocalJitter, TotalRemoteLocalJitter, c1.Circuit as Circuit1, c2.Circuit as Circuit2 FROM PCS_V1.NPAResults r JOIN PCS_V1.NpaResultsProfile p on r.PROFILEREFID = p.PROFILEREFID JOIN PCS_V1.NPAResultsAddress a on r.ADDRESSREFID = a.ADDRESSREFID JOIN PCS_V1.NPAResultsCircuit c1 on r.CIRCUIT1REFID = c1.CIRCUITREFID JOIN PCS_V1.NPAResultsCircuit c2 on r.CIRCUIT2REFID = c2.CIRCUITREFID WHERE ReportKey >= '2012-02-03 12:45:00.0' AND ReportKey <= '2012-02-14 14:00:00.0' AND (r.ResultFlag = 0 OR (r.ResultFlag <> 0 AND r.RoundTripPackets > 0)) ORDER BY TestResultDescription, Circuit1, TestResultDescription2, ProfileName, StartDateTime java.lang.OutOfMemoryError: Java heap space The server is a Oracle M3000 and the Derby engine heap is setup to be 8Gb. For a heap out of memory, I have seen occasional cases where Derby's estimate of whether it can sort in memory is wrong. You'd need to look at the plan and do some debugging with the actual query if you are able to reproduce to find out if that is the case here.
