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|    Message 2,142 of 2,288    |
|    Pentti to All    |
|    SQL re-parsing on query executed against    |
|    14 Oct 05 20:11:59    |
      From: penttik@gmail.com              Can anyone help to understand why re-parsing occurs on a remote database       (using database links), even though we are using a prepared statement on       the local database:              Scenario:       ========              We have an schema (s1) on an Oracle 9i database with database links       pointing to a schema (s2) on another Oracle 9i database.              We have a SQL statement which joins tables from schemas s1 to tables in       schema s2 by the use of database links (tablename@linkname). The query       is executed against schema s1.              The SQL statement is prepared and re-executed over many iterations       (using bind variables - Java/jdbc). The statement is closed only when we       have completed the iterations.              For both databases, the optimizer mode is CHOOSE and ALL the tables have       been analyzed.              Results:       =======              We have found that when we monitor / analyse the database, the parsing       rate is high, which is impacting the performance of the process.              NOTE: We also ran the same tests using Oracle 8i (for both databases)       instead of 9i. In these tests the parsing rate was very low (zero). This       is what I would have regarded as the expected behaviour.              The same high parsing rate is also seen when both schemas reside on the       same database, and database links are used to join tables from the 2       schemas. If however, the SQL query is amended to refer to the remote       tables in schema s2 by schema.tablename rather than tablename@linkname,       then the parsing rate is again very low (as expected) and the process       runs much more quickly.              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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