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IDProjectCategoryView StatusLast Update
0002137SymmetricDSBugpublic2025-02-26 18:40
Reporterbrickman Assigned To 
Prioritynormal 
Status feedbackResolutionopen 
Product Version3.5.17 
Summary0002137: Database performance degradation with large SYM_DATA
DescriptionOur setup is SymmetricDS 3.5.17 running against a Firebird 2.5.3 Super Classic database. We have 0000946:0000100 nodes connected.

As the number of SYM_DATA records increase we observe degradation in the database CPU utilisation. The increase was due to some nodes being offline for several days.

We found we could significantly improve performance if we added the following descending indexes (the syntax is Firebird):

CREATE DESCENDING INDEX IDX_SYM_DATA_ID_DESC ON SYM_DATA(DATA_ID);
CREATE DESCENDING INDEX IDX_SYM_DE_BATCHID_DESC ON SYM_DATA_EVENT(BATCH_ID);
CREATE DESCENDING INDEX IDX_SYM_OB_ID_DESC on SYM_OUTGOING_BATCH(BATCH_ID);

We initially had problems with SymmetricDS dropping these indexes on startup. We since worked around this by setting "auto.config.database" to false.

We also found that the symmetric-schema.xml config does not support descending indexes.

Is it possible to explore adding these indexes?
Tagsddl/schema, dialect: firebird, performance

Activities

emiller

2025-02-26 18:40

developer   ~0002644

Can you share the queries that have improved performance after creating these indexes?

The queries that we know of order by ascending.

Issue History

Date Modified Username Field Change
2015-01-15 05:53 brickman New Issue
2019-04-23 16:41 elong Tag Attached: ddl/schema
2019-04-23 16:41 elong Tag Attached: firebird
2019-04-23 16:43 elong Tag Attached: performance
2019-04-23 20:47 admin Tag Renamed firebird => dialect: firebird
2025-02-26 18:40 emiller Status new => feedback
2025-02-26 18:40 emiller Note Added: 0002644