Re: FetchSpec setFetchLimit??
Re: FetchSpec setFetchLimit??
- Subject: Re: FetchSpec setFetchLimit??
- From: Mark Gowdy <email@hidden>
- Date: Mon, 12 Jul 2010 16:27:15 +0100
On 2 Mar 2009, at 23:43, Chuck Hill wrote:
On Mar 2, 2009, at 1:42 PM, Kieran Kelleher wrote:
I always thought that EOFetchSpecification.setFetchLimit( int n)
would generate SQL with LIMIT n tacked onto the end of the SQL
statement, but it appears not to.
This is the default behavior as not all databases implement this.
Specific plugins add this, IIRC.
Chuck
Hi guys,
I have just stumbled into the same issue here:
I need to fetch the latest item from a table in a MySQL database,
where there are almost half a million items
I thought that fetchSpec.setFetchLimit(1) would tell the DB to do the
hard work, but this appears not to be the case.
Consequently, my app is exploding with 'out of memory' issues.
Is there a work around for this problem (some plug-in I am unaware
of), or do I need to get creative with raw-rows?
A solution would be good, because I was using these all over the
place (without knowledge of the consequences)
Thanks again,
Mark
Instead it fetches the all qualifying records and does the LIMIT
in memory?! Has this always been the case .... or is it just the
MySQL driver?
For example:
<snip>
// Fetch the most recent shipped message
ERXSortOrderings s = CTMessage.XKEY_OID.descs();
ERXFetchSpecification<CTMessage> fs = new
ERXFetchSpecification<CTMessage>(CTMessage.ENTITY_NAME,null,s);
fs.setFetchLimit(1);
System.out.println("MailingAddressUtilitiesTests.suppressionTest
(): fs.SQL = " + ERXEOAccessUtilities.sqlForFetchSpecification(ec,
fs));
NSArray<CTMessage> objects = fs.fetchObjects(ec);
</snip>
..... generates the following SQL without "LIMIT 1" !!!
SELECT t0.oid, t0.oidcampaign, t0.oiddatarecord, t0.oidjob,
t0.oidlocation, t0.oidmediatemplate, t0.recaddtime, t0.recadduser,
t0.recmodtime, t0.recmoduser, RTRIM(t0.workflowstate) FROM message
t0 ORDER BY t0.oid DESC;
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--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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