I think I forgot. regards Malcolm
On Thu, Jun 18, 2009 at 8:35 PM, Andrus Adamchik<and...@objectstyle.org> wrote: > Hi Malcolm, > > you are a committer :-). Nothing wrong with asking for a patch review, but > at the end you can just commit it yourself. > > Btw, we do have generic tests for fetch limit, you just need to run them > against SQLServer: > > http://cayenne.apache.org/running-unit-tests.html > > Andrus > > On Jun 18, 2009, at 1:17 PM, Malcolm Edgar wrote: > >> Hi Robert, >> >> JIRA and patch below. This does not include an automated unit test, >> however we have been testing it successfully on our servers. >> >> https://issues.apache.org/jira/browse/CAY-1244 >> >> regards Malcolm Edgar >> >> On Wed, Jun 17, 2009 at 12:20 PM, Robert >> Zeigler<robert.zeig...@roxanemy.com> wrote: >>> >>> setFetchLimit has been around for awhile, you're right. But the 2.0 >>> behavior >>> was, for all adapters, if I'm not mistaken, to do an in-memory fetch. 3.0 >>> added the ability to set the offset, and with it, added the option to set >>> the fetch limit at the database level. But, as mentioned, this behavior >>> isn't implemented for all adapters. >>> >>> Implementation in SelectTranslator: >>> >>> /** >>> * Handles appending optional limit and offset clauses. This >>> implementation does >>> * nothing, deferring to subclasses to define the LIMIT/OFFSET clause >>> syntax. >>> * >>> * @since 3.0 >>> */ >>> protected void appendLimitAndOffsetClauses(StringBuilder buffer) { >>> >>> } >>> >>> MySQL adapter uses a custom SelectTranslator to do: >>> >>> @Override >>> protected void appendLimitAndOffsetClauses(StringBuilder buffer) { >>> int offset = queryMetadata.getFetchOffset(); >>> int limit = queryMetadata.getFetchLimit(); >>> >>> if (offset > 0 || limit > 0) { >>> buffer.append(" LIMIT "); >>> >>> // both OFFSET and LIMIT must be present, so come up with >>> defaults if one of >>> // them is not set by the user >>> if (limit == 0) { >>> limit = Integer.MAX_VALUE; >>> } >>> >>> buffer.append(limit).append(" OFFSET ").append(offset); >>> } >>> } >>> >>> >>> The SQLAdapter, on the other hand, uses the default SelectTranslator >>> implementation. >>> Feel free to open an issue for SQLServer and supply a patch. :) I would >>> write it myself, but don't have access to SQLServer, nor am I >>> particularly >>> versed in its dialect of SQL. >>> But if you open the issue and supply a patch + tests, I'll be happy to >>> apply >>> the patch to the codebase. >>> >>> Robert >>> >>> On Jun 16, 2009, at 6/169:06 PM , Malcolm Edgar wrote: >>> >>>> Fetch limit has been around since Cayenne 2.0, and its not working as >>>> I expected. >>>> >>>> Stepping through the code its performing the limit operation after the >>>> query has been performed. For example a table with 100,000 rows will >>>> be read into memory even with a fetch limit of 100. Then Cayenne >>>> provides a wrapper around the iterator which returns only 100 records. >>>> >>>> This behaviour really needs to be documented, however more to the >>>> point this is not what I would expect from an ORM I would expect it to >>>> use the database to set the limit. >>>> >>>> For example: >>>> >>>> // mysql >>>> select col from tbl limit 20; >>>> >>>> // Oracle >>>> select col from tbl where rownum<=20; >>>> >>>> // Microsoft SQL >>>> select top 20 col from tbl; >>>> >>>> We are going to have to revisit a bunch of code after figuring this out >>>> :( >>>> >>>> regards Malcolm Edgar >>>> >>>> On Wed, Jun 17, 2009 at 11:37 AM, Robert >>>> Zeigler<robert.zeig...@roxanemy.com> wrote: >>>>> >>>>> I don't think the behavior changed, per se. Rather, setFetchLimit is a >>>>> relatively new feature, and may not be properly supported by all of the >>>>> db >>>>> adaptors yet. >>>>> >>>>> Robert >>>>> >>>>> On Jun 16, 2009, at 6/167:28 PM , Malcolm Edgar wrote: >>>>> >>>>>> Hi Guys, >>>>>> >>>>>> On SQL Server we are finding that the setting the Fetch Limit on a >>>>>> SelectQuery does not modify the SQL query, to set TOP or SET ROWCOUNT, >>>>>> so the database is not limiting the number of rows returned, and it >>>>>> appears that Cayenne is limiting the number of rows returned in >>>>>> memory? >>>>>> >>>>>> This is killing our application with OOM errors. Did this behaviour >>>>>> change? We are using Cayenne 3.0M5 >>>>>> >>>>>> regards Malcolm Edgar >>>>> >>>>> >>> >>> >> > >
