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https://issues.apache.org/jira/browse/DERBY-5151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011241#comment-13011241
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Rick Hillegas commented on DERBY-5151:
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Thanks Bryan and Mark for continuing the discussion. Here are pointers to the
syntax used by some other databases:
Oracle: http://www.dba-oracle.com/t_oracle_create_sequence.htm
DB2:
http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/admin/r0004201.htm
Postgres: http://www.postgresql.org/docs/8.1/static/sql-createsequence.html
>From these links, it appears to me that Oracle and DB2 support identical
>syntax:
[ CACHE cacheSize | NOCACHE ] // the default is CACHE 20
Postgres supports slightly different syntax:
[ CACHE cacheSize ] // the default is CACHE 1, which means caching is turned
off
I agree with Mark and Bryan that adding more property-based knobs is awkward. I
share Bryan's concerns that the proposed SQL syntax has not made it into the
standard yet. However, I am encouraged by the agreement between Oracle and DB2
and by the overlap with Postgres. The Postgres syntax would be compatible with
all 3 databases.
I would be comfortable with the Postgres syntax, preserving the current Derby
default of cacheSize=5. I would also be comfortable with the extra NOCACHE
syntactic sugar supported by Oracle and DB2. Other opinions?
Thanks,
-Rick
> Sequence without cache
> ----------------------
>
> Key: DERBY-5151
> URL: https://issues.apache.org/jira/browse/DERBY-5151
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Mark Holster
> Attachments: sequence-no-cache.patch
>
>
> Currently, a sequence in Derby always uses a pre allocating cache. I'm
> working on an usecase which requires a number to increase with a fixed value.
> The usecase fails after a restart because of the pre allocating cache.
> I've created a patch that adds the options CACHE | NO CACHE to the create
> sequence statement. When no cache is provided, the pre allocating cache size
> will be set to 1, which results in a "no cache sequence".
> I've followed the CYCLE | NO CYCLE code as much as possible. Tested it in my
> own app and it seems to work fine.
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