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From "Bergquist, Brett" <BBergqu...@canoga.com>
Subject Re: Performance issue with same index name in multiple schemas
Date Fri, 05 Feb 2016 14:39:06 GMT
You should run your queries and take a look at the query plans being used.  It may be possible
that your indexes are not being used as you think.   See

http://db.apache.org/derby/docs/10.10/tuning/index.html

the section on "How you use the RUNTIMESTATISTICS attribute”

Possibly the statistics used by the optimizer are not up to date.  Initially when an index
is created and if the table is empty, no statistics are created for the index and subsequently
the optimizer may not choose to use the index even though later there may be many rows in
the table and the index may be the preferred mechanism.

Also take a look at "Selectivity and cardinality statistics” and especially how to update
the statistics in

http://db.apache.org/derby/docs/10.10/ref/index.html

for the “SYSCS_UTIL.SYSCS_UPDATE_STATISTICS” function.  Also look to see if the index
statistics daemon is enabled.   Look at the “derby.storage.indexStats.auto” property.

> On Feb 5, 2016, at 7:22 AM, kosurusekhar <kosurusekhar@gmail.com> wrote:
>
> Hi All,
>
> We are having three schemas with almost same table structure, indexes,
> queries, stored procedures in one database. But in one schema we are facing
> some performance issue. We are having same index names and table names in
> all schemas. In another schemas it is running without any problem. In one
> schema with basic load only application is becoming slow.
>
> Is there any relationship with table names and index names with multiple
> schemas? What ever we have queries/stored procedure's with performance
> issues, these queries/stored procedure's running with out any issue in
> another schema's. I am not understanding what is going wrong.
>
> I could see some times single transaction is locking couple of tables more
> than once and not releasing. At this point of time we are feeling the
> slowness.
>
> Please help me with some points to sort out this situation.
>
> Thanks in advance.
>
> Regards
> Sekhar.
>
>
>
> --
> View this message in context: http://apache-database.10148.n7.nabble.com/Performance-issue-with-same-index-name-in-multiple-schemas-tp145507.html
> Sent from the Apache Derby Users mailing list archive at Nabble.com.


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